


JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                        January 13, 2015
Expires: July 17, 2015


                       JSON Web Algorithms (JWA)
                 draft-ietf-jose-json-web-algorithms-40

Abstract

   The JSON Web Algorithms (JWA) specification registers cryptographic
   algorithms and identifiers to be used with the JSON Web Signature
   (JWS), JSON Web Encryption (JWE), and JSON Web Key (JWK)
   specifications.  It defines several IANA registries for these
   identifiers.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on July 17, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Cryptographic Algorithms for Digital Signatures and MACs . . .  6
     3.1.  "alg" (Algorithm) Header Parameter Values for JWS  . . . .  6
     3.2.  HMAC with SHA-2 Functions  . . . . . . . . . . . . . . . .  7
     3.3.  Digital Signature with RSASSA-PKCS1-V1_5 . . . . . . . . .  8
     3.4.  Digital Signature with ECDSA . . . . . . . . . . . . . . .  9
     3.5.  Digital Signature with RSASSA-PSS  . . . . . . . . . . . . 11
     3.6.  Using the Algorithm "none" . . . . . . . . . . . . . . . . 12
   4.  Cryptographic Algorithms for Key Management  . . . . . . . . . 12
     4.1.  "alg" (Algorithm) Header Parameter Values for JWE  . . . . 12
     4.2.  Key Encryption with RSAES-PKCS1-V1_5 . . . . . . . . . . . 14
     4.3.  Key Encryption with RSAES OAEP . . . . . . . . . . . . . . 14
     4.4.  Key Wrapping with AES Key Wrap . . . . . . . . . . . . . . 15
     4.5.  Direct Encryption with a Shared Symmetric Key  . . . . . . 16
     4.6.  Key Agreement with Elliptic Curve Diffie-Hellman
           Ephemeral Static (ECDH-ES) . . . . . . . . . . . . . . . . 16
       4.6.1.  Header Parameters Used for ECDH Key Agreement  . . . . 17
         4.6.1.1.  "epk" (Ephemeral Public Key) Header Parameter  . . 17
         4.6.1.2.  "apu" (Agreement PartyUInfo) Header Parameter  . . 17
         4.6.1.3.  "apv" (Agreement PartyVInfo) Header Parameter  . . 17
       4.6.2.  Key Derivation for ECDH Key Agreement  . . . . . . . . 18
     4.7.  Key Encryption with AES GCM  . . . . . . . . . . . . . . . 19
       4.7.1.  Header Parameters Used for AES GCM Key Encryption  . . 20
         4.7.1.1.  "iv" (Initialization Vector) Header Parameter  . . 20
         4.7.1.2.  "tag" (Authentication Tag) Header Parameter  . . . 20
     4.8.  Key Encryption with PBES2  . . . . . . . . . . . . . . . . 20
       4.8.1.  Header Parameters Used for PBES2 Key Encryption  . . . 21
         4.8.1.1.  "p2s" (PBES2 salt input) Parameter . . . . . . . . 21
         4.8.1.2.  "p2c" (PBES2 count) Parameter  . . . . . . . . . . 21
   5.  Cryptographic Algorithms for Content Encryption  . . . . . . . 22
     5.1.  "enc" (Encryption Algorithm) Header Parameter Values
           for JWE  . . . . . . . . . . . . . . . . . . . . . . . . . 22
     5.2.  AES_CBC_HMAC_SHA2 Algorithms . . . . . . . . . . . . . . . 23
       5.2.1.  Conventions Used in Defining AES_CBC_HMAC_SHA2 . . . . 23
       5.2.2.  Generic AES_CBC_HMAC_SHA2 Algorithm  . . . . . . . . . 23
         5.2.2.1.  AES_CBC_HMAC_SHA2 Encryption . . . . . . . . . . . 23
         5.2.2.2.  AES_CBC_HMAC_SHA2 Decryption . . . . . . . . . . . 25
       5.2.3.  AES_128_CBC_HMAC_SHA_256 . . . . . . . . . . . . . . . 25
       5.2.4.  AES_192_CBC_HMAC_SHA_384 . . . . . . . . . . . . . . . 26
       5.2.5.  AES_256_CBC_HMAC_SHA_512 . . . . . . . . . . . . . . . 26
       5.2.6.  Content Encryption with AES_CBC_HMAC_SHA2  . . . . . . 27
     5.3.  Content Encryption with AES GCM  . . . . . . . . . . . . . 27
   6.  Cryptographic Algorithms for Keys  . . . . . . . . . . . . . . 28
     6.1.  "kty" (Key Type) Parameter Values  . . . . . . . . . . . . 28



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     6.2.  Parameters for Elliptic Curve Keys . . . . . . . . . . . . 28
       6.2.1.  Parameters for Elliptic Curve Public Keys  . . . . . . 28
         6.2.1.1.  "crv" (Curve) Parameter  . . . . . . . . . . . . . 29
         6.2.1.2.  "x" (X Coordinate) Parameter . . . . . . . . . . . 29
         6.2.1.3.  "y" (Y Coordinate) Parameter . . . . . . . . . . . 29
       6.2.2.  Parameters for Elliptic Curve Private Keys . . . . . . 30
         6.2.2.1.  "d" (ECC Private Key) Parameter  . . . . . . . . . 30
     6.3.  Parameters for RSA Keys  . . . . . . . . . . . . . . . . . 30
       6.3.1.  Parameters for RSA Public Keys . . . . . . . . . . . . 30
         6.3.1.1.  "n" (Modulus) Parameter  . . . . . . . . . . . . . 30
         6.3.1.2.  "e" (Exponent) Parameter . . . . . . . . . . . . . 30
       6.3.2.  Parameters for RSA Private Keys  . . . . . . . . . . . 31
         6.3.2.1.  "d" (Private Exponent) Parameter . . . . . . . . . 31
         6.3.2.2.  "p" (First Prime Factor) Parameter . . . . . . . . 31
         6.3.2.3.  "q" (Second Prime Factor) Parameter  . . . . . . . 31
         6.3.2.4.  "dp" (First Factor CRT Exponent) Parameter . . . . 31
         6.3.2.5.  "dq" (Second Factor CRT Exponent) Parameter  . . . 31
         6.3.2.6.  "qi" (First CRT Coefficient) Parameter . . . . . . 31
         6.3.2.7.  "oth" (Other Primes Info) Parameter  . . . . . . . 32
     6.4.  Parameters for Symmetric Keys  . . . . . . . . . . . . . . 32
       6.4.1.  "k" (Key Value) Parameter  . . . . . . . . . . . . . . 32
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 33
     7.1.  JSON Web Signature and Encryption Algorithms Registry  . . 34
       7.1.1.  Registration Template  . . . . . . . . . . . . . . . . 34
       7.1.2.  Initial Registry Contents  . . . . . . . . . . . . . . 36
     7.2.  Header Parameter Names Registration  . . . . . . . . . . . 42
       7.2.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 42
     7.3.  JSON Web Encryption Compression Algorithms Registry  . . . 43
       7.3.1.  Registration Template  . . . . . . . . . . . . . . . . 43
       7.3.2.  Initial Registry Contents  . . . . . . . . . . . . . . 44
     7.4.  JSON Web Key Types Registry  . . . . . . . . . . . . . . . 44
       7.4.1.  Registration Template  . . . . . . . . . . . . . . . . 45
       7.4.2.  Initial Registry Contents  . . . . . . . . . . . . . . 45
     7.5.  JSON Web Key Parameters Registration . . . . . . . . . . . 46
       7.5.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 46
     7.6.  JSON Web Key Elliptic Curve Registry . . . . . . . . . . . 48
       7.6.1.  Registration Template  . . . . . . . . . . . . . . . . 48
       7.6.2.  Initial Registry Contents  . . . . . . . . . . . . . . 49
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 50
     8.1.  Cryptographic Agility  . . . . . . . . . . . . . . . . . . 50
     8.2.  Key Lifetimes  . . . . . . . . . . . . . . . . . . . . . . 50
     8.3.  RSAES-PKCS1-v1_5 Security Considerations . . . . . . . . . 50
     8.4.  AES GCM Security Considerations  . . . . . . . . . . . . . 50
     8.5.  Unsecured JWS Security Considerations  . . . . . . . . . . 51
     8.6.  Denial of Service Attacks  . . . . . . . . . . . . . . . . 51
     8.7.  Reusing Key Material when Encrypting Keys  . . . . . . . . 52
     8.8.  Password Considerations  . . . . . . . . . . . . . . . . . 52
     8.9.  Key Entropy and Random Values  . . . . . . . . . . . . . . 53



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     8.10. Differences between Digital Signatures and MACs  . . . . . 53
     8.11. Using Matching Algorithm Strengths . . . . . . . . . . . . 53
     8.12. Adaptive Chosen-Ciphertext Attacks . . . . . . . . . . . . 53
     8.13. Timing Attacks . . . . . . . . . . . . . . . . . . . . . . 53
     8.14. RSA Private Key Representations and Blinding . . . . . . . 53
   9.  Internationalization Considerations  . . . . . . . . . . . . . 53
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 53
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 53
     10.2. Informative References . . . . . . . . . . . . . . . . . . 55
   Appendix A.  Algorithm Identifier Cross-Reference  . . . . . . . . 57
     A.1.  Digital Signature/MAC Algorithm Identifier
           Cross-Reference  . . . . . . . . . . . . . . . . . . . . . 58
     A.2.  Key Management Algorithm Identifier Cross-Reference  . . . 58
     A.3.  Content Encryption Algorithm Identifier Cross-Reference  . 59
   Appendix B.  Test Cases for AES_CBC_HMAC_SHA2 Algorithms . . . . . 60
     B.1.  Test Cases for AES_128_CBC_HMAC_SHA_256  . . . . . . . . . 61
     B.2.  Test Cases for AES_192_CBC_HMAC_SHA_384  . . . . . . . . . 62
     B.3.  Test Cases for AES_256_CBC_HMAC_SHA_512  . . . . . . . . . 63
   Appendix C.  Example ECDH-ES Key Agreement Computation . . . . . . 64
   Appendix D.  Acknowledgements  . . . . . . . . . . . . . . . . . . 66
   Appendix E.  Document History  . . . . . . . . . . . . . . . . . . 67
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 78





























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1.  Introduction

   The JSON Web Algorithms (JWA) specification registers cryptographic
   algorithms and identifiers to be used with the JSON Web Signature
   (JWS) [JWS], JSON Web Encryption (JWE) [JWE], and JSON Web Key (JWK)
   [JWK] specifications.  It defines several IANA registries for these
   identifiers.  All these specifications utilize JavaScript Object
   Notation (JSON) [RFC7159] based data structures.  This specification
   also describes the semantics and operations that are specific to
   these algorithms and key types.

   Registering the algorithms and identifiers here, rather than in the
   JWS, JWE, and JWK specifications, is intended to allow them to remain
   unchanged in the face of changes in the set of Required, Recommended,
   Optional, and Deprecated algorithms over time.  This also allows
   changes to the JWS, JWE, and JWK specifications without changing this
   document.

   Names defined by this specification are short because a core goal is
   for the resulting representations to be compact.

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in Key
   words for use in RFCs to Indicate Requirement Levels [RFC2119].  If
   these words are used without being spelled in uppercase then they are
   to be interpreted with their normal natural language meanings.

   BASE64URL(OCTETS) denotes the base64url encoding of OCTETS, per
   Section 2 of [JWS].

   UTF8(STRING) denotes the octets of the UTF-8 [RFC3629] representation
   of STRING, where STRING is a sequence of zero or more Unicode
   [UNICODE] characters.

   ASCII(STRING) denotes the octets of the ASCII [RFC20] representation
   of STRING, where STRING is a sequence of zero or more ASCII
   characters.

   The concatenation of two values A and B is denoted as A || B.


2.  Terminology

   These terms defined by the JSON Web Signature (JWS) [JWS]
   specification are incorporated into this specification: "JSON Web



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   Signature (JWS)", "Base64url Encoding", "Header Parameter", "JOSE
   Header", "JWS Payload", "JWS Protected Header", "JWS Signature", "JWS
   Signing Input", and "Unsecured JWS".

   These terms defined by the JSON Web Encryption (JWE) [JWE]
   specification are incorporated into this specification: "JSON Web
   Encryption (JWE)", "Additional Authenticated Data (AAD)",
   "Authentication Tag", "Content Encryption Key (CEK)", "Direct
   Encryption", "Direct Key Agreement", "JWE Authentication Tag", "JWE
   Ciphertext", "JWE Encrypted Key", "JWE Initialization Vector", "JWE
   Protected Header", "Key Agreement with Key Wrapping", "Key
   Encryption", "Key Management Mode", and "Key Wrapping".

   These terms defined by the JSON Web Key (JWK) [JWK] specification are
   incorporated into this specification: "JSON Web Key (JWK)" and "JSON
   Web Key Set (JWK Set)".

   These terms defined by the Internet Security Glossary, Version 2
   [RFC4949] are incorporated into this specification: "Ciphertext",
   "Digital Signature", "Message Authentication Code (MAC)", and
   "Plaintext".

   This term is defined by this specification:

   Base64urlUInt
      The representation of a positive or zero integer value as the
      base64url encoding of the value's unsigned big endian
      representation as an octet sequence.  The octet sequence MUST
      utilize the minimum number of octets needed to represent the
      value.  Zero is represented as BASE64URL(single zero-valued
      octet), which is "AA".


3.  Cryptographic Algorithms for Digital Signatures and MACs

   JWS uses cryptographic algorithms to digitally sign or create a
   Message Authentication Code (MAC) of the contents of the JWS
   Protected Header and the JWS Payload.

3.1.  "alg" (Algorithm) Header Parameter Values for JWS

   The table below is the set of "alg" (algorithm) header parameter
   values defined by this specification for use with JWS, each of which
   is explained in more detail in the following sections:







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   +--------------+-----------------------------------+----------------+
   | alg Param    | Digital Signature or MAC          | Implementation |
   | Value        | Algorithm                         | Requirements   |
   +--------------+-----------------------------------+----------------+
   | HS256        | HMAC using SHA-256                | Required       |
   | HS384        | HMAC using SHA-384                | Optional       |
   | HS512        | HMAC using SHA-512                | Optional       |
   | RS256        | RSASSA-PKCS-v1_5 using SHA-256    | Recommended    |
   | RS384        | RSASSA-PKCS-v1_5 using SHA-384    | Optional       |
   | RS512        | RSASSA-PKCS-v1_5 using SHA-512    | Optional       |
   | ES256        | ECDSA using P-256 and SHA-256     | Recommended+   |
   | ES384        | ECDSA using P-384 and SHA-384     | Optional       |
   | ES512        | ECDSA using P-521 and SHA-512     | Optional       |
   | PS256        | RSASSA-PSS using SHA-256 and MGF1 | Optional       |
   |              | with SHA-256                      |                |
   | PS384        | RSASSA-PSS using SHA-384 and MGF1 | Optional       |
   |              | with SHA-384                      |                |
   | PS512        | RSASSA-PSS using SHA-512 and MGF1 | Optional       |
   |              | with SHA-512                      |                |
   | none         | No digital signature or MAC       | Optional       |
   |              | performed                         |                |
   +--------------+-----------------------------------+----------------+

   The use of "+" in the Implementation Requirements indicates that the
   requirement strength is likely to be increased in a future version of
   the specification.

   See Appendix A.1 for a table cross-referencing the JWS digital
   signature and MAC "alg" (algorithm) values defined in this
   specification with the equivalent identifiers used by other standards
   and software packages.

3.2.  HMAC with SHA-2 Functions

   Hash-based Message Authentication Codes (HMACs) enable one to use a
   secret plus a cryptographic hash function to generate a Message
   Authentication Code (MAC).  This can be used to demonstrate that
   whoever generated the MAC was in possession of the MAC key.  The
   algorithm for implementing and validating HMACs is provided in RFC
   2104 [RFC2104].

   A key of the same size as the hash output (for instance, 256 bits for
   "HS256") or larger MUST be used with this algorithm.  (This
   requirement is based on Section 5.3.4 (Security Effect of the HMAC
   Key) of NIST SP 800-117 [NIST.800-107], which states that the
   effective security strength is the minimum of the security strength
   of the key and two times the size of the internal hash value.)




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   The HMAC SHA-256 MAC is generated per RFC 2104, using SHA-256 as the
   hash algorithm "H", using the JWS Signing Input as the "text" value,
   and using the shared key.  The HMAC output value is the JWS
   Signature.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWS Signature is an HMAC value computed using the
   corresponding algorithm:

                 +-----------------+--------------------+
                 | alg Param Value | MAC Algorithm      |
                 +-----------------+--------------------+
                 | HS256           | HMAC using SHA-256 |
                 | HS384           | HMAC using SHA-384 |
                 | HS512           | HMAC using SHA-512 |
                 +-----------------+--------------------+

   The HMAC SHA-256 MAC for a JWS is validated by computing an HMAC
   value per RFC 2104, using SHA-256 as the hash algorithm "H", using
   the received JWS Signing Input as the "text" value, and using the
   shared key.  This computed HMAC value is then compared to the result
   of base64url decoding the received encoded JWS Signature value.  The
   comparison of the computed HMAC value to the JWS Signature value MUST
   be done in a constant-time manner to thwart timing attacks.
   Alternatively, the computed HMAC value can be base64url encoded and
   compared to the received encoded JWS Signature value (also in a
   constant-time manner), as this comparison produces the same result as
   comparing the unencoded values.  In either case, if the values match,
   the HMAC has been validated.

   Securing content and validation with the HMAC SHA-384 and HMAC SHA-
   512 algorithms is performed identically to the procedure for HMAC
   SHA-256 -- just using the corresponding hash algorithms with
   correspondingly larger minimum key sizes and result values: 384 bits
   each for HMAC SHA-384 and 512 bits each for HMAC SHA-512.

   An example using this algorithm is shown in Appendix A.1 of [JWS].

3.3.  Digital Signature with RSASSA-PKCS1-V1_5

   This section defines the use of the RSASSA-PKCS1-V1_5 digital
   signature algorithm as defined in Section 8.2 of RFC 3447 [RFC3447]
   (commonly known as PKCS #1), using SHA-2 [SHS] hash functions.

   A key of size 2048 bits or larger MUST be used with these algorithms.

   The RSASSA-PKCS1-V1_5 SHA-256 digital signature is generated as
   follows: Generate a digital signature of the JWS Signing Input using



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   RSASSA-PKCS1-V1_5-SIGN and the SHA-256 hash function with the desired
   private key.  This is the JWS Signature value.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWS Signature is a digital signature value computed
   using the corresponding algorithm:

           +-----------------+--------------------------------+
           | alg Param Value | Digital Signature Algorithm    |
           +-----------------+--------------------------------+
           | RS256           | RSASSA-PKCS-v1_5 using SHA-256 |
           | RS384           | RSASSA-PKCS-v1_5 using SHA-384 |
           | RS512           | RSASSA-PKCS-v1_5 using SHA-512 |
           +-----------------+--------------------------------+

   The RSASSA-PKCS1-V1_5 SHA-256 digital signature for a JWS is
   validated as follows: Submit the JWS Signing Input, the JWS
   Signature, and the public key corresponding to the private key used
   by the signer to the RSASSA-PKCS1-V1_5-VERIFY algorithm using SHA-256
   as the hash function.

   Signing and validation with the RSASSA-PKCS1-V1_5 SHA-384 and RSASSA-
   PKCS1-V1_5 SHA-512 algorithms is performed identically to the
   procedure for RSASSA-PKCS1-V1_5 SHA-256 -- just using the
   corresponding hash algorithms instead of SHA-256.

   An example using this algorithm is shown in Appendix A.2 of [JWS].

3.4.  Digital Signature with ECDSA

   The Elliptic Curve Digital Signature Algorithm (ECDSA) [DSS] provides
   for the use of Elliptic Curve cryptography, which is able to provide
   equivalent security to RSA cryptography but using shorter key sizes
   and with greater processing speed for many operations.  This means
   that ECDSA digital signatures will be substantially smaller in terms
   of length than equivalently strong RSA digital signatures.

   This specification defines the use of ECDSA with the P-256 curve and
   the SHA-256 cryptographic hash function, ECDSA with the P-384 curve
   and the SHA-384 hash function, and ECDSA with the P-521 curve and the
   SHA-512 hash function.  The P-256, P-384, and P-521 curves are
   defined in [DSS].

   The ECDSA P-256 SHA-256 digital signature is generated as follows:

   1.  Generate a digital signature of the JWS Signing Input using ECDSA
       P-256 SHA-256 with the desired private key.  The output will be
       the pair (R, S), where R and S are 256 bit unsigned integers.



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   2.  Turn R and S into octet sequences in big endian order, with each
       array being be 32 octets long.  The octet sequence
       representations MUST NOT be shortened to omit any leading zero
       octets contained in the values.

   3.  Concatenate the two octet sequences in the order R and then S.
       (Note that many ECDSA implementations will directly produce this
       concatenation as their output.)

   4.  The resulting 64 octet sequence is the JWS Signature value.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWS Signature is a digital signature value computed
   using the corresponding algorithm:

            +-----------------+-------------------------------+
            | alg Param Value | Digital Signature Algorithm   |
            +-----------------+-------------------------------+
            | ES256           | ECDSA using P-256 and SHA-256 |
            | ES384           | ECDSA using P-384 and SHA-384 |
            | ES512           | ECDSA using P-521 and SHA-512 |
            +-----------------+-------------------------------+

   The ECDSA P-256 SHA-256 digital signature for a JWS is validated as
   follows:

   1.  The JWS Signature value MUST be a 64 octet sequence.  If it is
       not a 64 octet sequence, the validation has failed.

   2.  Split the 64 octet sequence into two 32 octet sequences.  The
       first octet sequence represents R and the second S. The values R
       and S are represented as octet sequences using the Integer-to-
       OctetString Conversion defined in Section 2.3.7 of SEC1 [SEC1]
       (in big endian octet order).

   3.  Submit the JWS Signing Input R, S and the public key (x, y) to
       the ECDSA P-256 SHA-256 validator.

   Signing and validation with the ECDSA P-384 SHA-384 and ECDSA P-521
   SHA-512 algorithms is performed identically to the procedure for
   ECDSA P-256 SHA-256 -- just using the corresponding hash algorithms
   with correspondingly larger result values.  For ECDSA P-384 SHA-384,
   R and S will be 384 bits each, resulting in a 96 octet sequence.  For
   ECDSA P-521 SHA-512, R and S will be 521 bits each, resulting in a
   132 octet sequence.  (Note that the Integer-to-OctetString Conversion
   defined in Section 2.3.7 of SEC1 [SEC1] used to represent R and S as
   octet sequences adds zero-valued high-order padding bits when needed
   to round the size up to a multiple of 8 bits; thus, each 521-bit



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   integer is represented using 528 bits in 66 octets.)

   Examples using these algorithms are shown in Appendices A.3 and A.4
   of [JWS].

3.5.  Digital Signature with RSASSA-PSS

   This section defines the use of the RSASSA-PSS digital signature
   algorithm as defined in Section 8.1 of RFC 3447 [RFC3447] with the
   MGF1 mask generation function and SHA-2 hash functions, always using
   the same hash function for both the RSASSA-PSS hash function and the
   MGF1 hash function.  The size of the salt value is the same size as
   the hash function output.  All other algorithm parameters use the
   defaults specified in Section A.2.3 of RFC 3447.

   A key of size 2048 bits or larger MUST be used with this algorithm.

   The RSASSA-PSS SHA-256 digital signature is generated as follows:
   Generate a digital signature of the JWS Signing Input using RSASSA-
   PSS-SIGN, the SHA-256 hash function, and the MGF1 mask generation
   function with SHA-256 with the desired private key.  This is the JWS
   signature value.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWS Signature is a digital signature value computed
   using the corresponding algorithm:

   +-----------------+------------------------------------------------+
   | alg Param Value | Digital Signature Algorithm                    |
   +-----------------+------------------------------------------------+
   | PS256           | RSASSA-PSS using SHA-256 and MGF1 with SHA-256 |
   | PS384           | RSASSA-PSS using SHA-384 and MGF1 with SHA-384 |
   | PS512           | RSASSA-PSS using SHA-512 and MGF1 with SHA-512 |
   +-----------------+------------------------------------------------+

   The RSASSA-PSS SHA-256 digital signature for a JWS is validated as
   follows: Submit the JWS Signing Input, the JWS Signature, and the
   public key corresponding to the private key used by the signer to the
   RSASSA-PSS-VERIFY algorithm using SHA-256 as the hash function and
   using MGF1 as the mask generation function with SHA-256.

   Signing and validation with the RSASSA-PSS SHA-384 and RSASSA-PSS
   SHA-512 algorithms is performed identically to the procedure for
   RSASSA-PSS SHA-256 -- just using the alternative hash algorithm in
   both roles.






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3.6.  Using the Algorithm "none"

   JWSs MAY also be created that do not provide integrity protection.
   Such a JWS is called an Unsecured JWS.  An Unsecured JWS uses the
   "alg" value "none" and is formatted identically to other JWSs, but
   MUST use the empty octet sequence as its JWS Signature value.
   Recipients MUST verify that the JWS Signature value is the empty
   octet sequence.

   Implementations that support Unsecured JWSs MUST NOT accept such
   objects as valid unless the application specifies that it is
   acceptable for a specific object to not be integrity protected.
   Implementations MUST NOT accept Unsecured JWSs by default.  In order
   to mitigate downgrade attacks, applications MUST NOT signal
   acceptance of Unsecured JWSs at a global level, and SHOULD signal
   acceptance on a per-object basis.  See Section 8.5 for security
   considerations associated with using this algorithm.


4.  Cryptographic Algorithms for Key Management

   JWE uses cryptographic algorithms to encrypt or determine the Content
   Encryption Key (CEK).

4.1.  "alg" (Algorithm) Header Parameter Values for JWE

   The table below is the set of "alg" (algorithm) Header Parameter
   values that are defined by this specification for use with JWE.
   These algorithms are used to encrypt the CEK, producing the JWE
   Encrypted Key, or to use key agreement to agree upon the CEK.





















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   +--------------------+--------------------+--------+----------------+
   | alg Param Value    | Key Management     | More   | Implementation |
   |                    | Algorithm          | Header | Requirements   |
   |                    |                    | Params |                |
   +--------------------+--------------------+--------+----------------+
   | RSA1_5             | RSAES-PKCS1-V1_5   | (none) | Recommended-   |
   | RSA-OAEP           | RSAES OAEP using   | (none) | Recommended+   |
   |                    | default parameters |        |                |
   | RSA-OAEP-256       | RSAES OAEP using   | (none) | Optional       |
   |                    | SHA-256 and MGF1   |        |                |
   |                    | with SHA-256       |        |                |
   | A128KW             | AES Key Wrap with  | (none) | Recommended    |
   |                    | default initial    |        |                |
   |                    | value using 128    |        |                |
   |                    | bit key            |        |                |
   | A192KW             | AES Key Wrap with  | (none) | Optional       |
   |                    | default initial    |        |                |
   |                    | value using 192    |        |                |
   |                    | bit key            |        |                |
   | A256KW             | AES Key Wrap with  | (none) | Recommended    |
   |                    | default initial    |        |                |
   |                    | value using 256    |        |                |
   |                    | bit key            |        |                |
   | dir                | Direct use of a    | (none) | Recommended    |
   |                    | shared symmetric   |        |                |
   |                    | key as the CEK     |        |                |
   | ECDH-ES            | Elliptic Curve     | "epk", | Recommended+   |
   |                    | Diffie-Hellman     | "apu", |                |
   |                    | Ephemeral Static   | "apv"  |                |
   |                    | key agreement      |        |                |
   |                    | using Concat KDF   |        |                |
   | ECDH-ES+A128KW     | ECDH-ES using      | "epk", | Recommended    |
   |                    | Concat KDF and CEK | "apu", |                |
   |                    | wrapped with       | "apv"  |                |
   |                    | "A128KW"           |        |                |
   | ECDH-ES+A192KW     | ECDH-ES using      | "epk", | Optional       |
   |                    | Concat KDF and CEK | "apu", |                |
   |                    | wrapped with       | "apv"  |                |
   |                    | "A192KW"           |        |                |
   | ECDH-ES+A256KW     | ECDH-ES using      | "epk", | Recommended    |
   |                    | Concat KDF and CEK | "apu", |                |
   |                    | wrapped with       | "apv"  |                |
   |                    | "A256KW"           |        |                |
   | A128GCMKW          | Key wrapping with  | "iv",  | Optional       |
   |                    | AES GCM using 128  | "tag"  |                |
   |                    | bit key            |        |                |





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   | A192GCMKW          | Key wrapping with  | "iv",  | Optional       |
   |                    | AES GCM using 192  | "tag"  |                |
   |                    | bit key            |        |                |
   | A256GCMKW          | Key wrapping with  | "iv",  | Optional       |
   |                    | AES GCM using 256  | "tag"  |                |
   |                    | bit key            |        |                |
   | PBES2-HS256+A128KW | PBES2 with HMAC    | "p2s", | Optional       |
   |                    | SHA-256 and        | "p2c"  |                |
   |                    | "A128KW" wrapping  |        |                |
   | PBES2-HS384+A192KW | PBES2 with HMAC    | "p2s", | Optional       |
   |                    | SHA-384 and        | "p2c"  |                |
   |                    | "A192KW" wrapping  |        |                |
   | PBES2-HS512+A256KW | PBES2 with HMAC    | "p2s", | Optional       |
   |                    | SHA-512 and        | "p2c"  |                |
   |                    | "A256KW" wrapping  |        |                |
   +--------------------+--------------------+--------+----------------+

   The More Header Params column indicates what additional Header
   Parameters are used by the algorithm, beyond "alg", which all use.
   All but "dir" and "ECDH-ES" also produce a JWE Encrypted Key value.

   The use of "+" in the Implementation Requirements indicates that the
   requirement strength is likely to be increased in a future version of
   the specification.

   See Appendix A.2 for a table cross-referencing the JWE "alg"
   (algorithm) values defined in this specification with the equivalent
   identifiers used by other standards and software packages.

4.2.  Key Encryption with RSAES-PKCS1-V1_5

   This section defines the specifics of encrypting a JWE CEK with
   RSAES-PKCS1-V1_5 [RFC3447].  The "alg" Header Parameter value
   "RSA1_5" is used for this algorithm.

   A key of size 2048 bits or larger MUST be used with this algorithm.

   An example using this algorithm is shown in Appendix A.2 of [JWE].

4.3.  Key Encryption with RSAES OAEP

   This section defines the specifics of encrypting a JWE CEK with RSAES
   using Optimal Asymmetric Encryption Padding (OAEP) [RFC3447].  Two
   sets of parameters for using OAEP are defined, which use different
   hash functions.  In the first case, the default parameters specified
   by RFC 3447 in Section A.2.1 are used.  (Those default parameters are
   the SHA-1 hash function and the MGF1 with SHA-1 mask generation
   function.)  In the second case, the SHA-256 hash function and the



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   MGF1 with SHA-256 mask generation function are used.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWE Encrypted Key is the result of encrypting the
   CEK using the corresponding algorithm:

   +-----------------+------------------------------------------------+
   | alg Param Value | Key Management Algorithm                       |
   +-----------------+------------------------------------------------+
   | RSA-OAEP        | RSAES OAEP using default parameters            |
   | RSA-OAEP-256    | RSAES OAEP using SHA-256 and MGF1 with SHA-256 |
   +-----------------+------------------------------------------------+

   A key of size 2048 bits or larger MUST be used with these algorithms.
   (This requirement is based on Table 4 (Security-strength time frames)
   of NIST SP 800-57 [NIST.800-57], which requires 112 bits of security
   for new uses, and Table 2 (Comparable strengths) of the same, which
   states that 2048 bit RSA keys provide 112 bits of security.)

   An example using RSAES OAEP with the default parameters is shown in
   Appendix A.1 of [JWE].

4.4.  Key Wrapping with AES Key Wrap

   This section defines the specifics of encrypting a JWE CEK with the
   Advanced Encryption Standard (AES) Key Wrap Algorithm [RFC3394] using
   the default initial value specified in Section 2.2.3.1.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWE Encrypted Key is the result of encrypting the
   CEK using the corresponding algorithm and key size:

   +---------------+---------------------------------------------------+
   | alg Param     | Key Management Algorithm                          |
   | Value         |                                                   |
   +---------------+---------------------------------------------------+
   | A128KW        | AES Key Wrap with default initial value using 128 |
   |               | bit key                                           |
   | A192KW        | AES Key Wrap with default initial value using 192 |
   |               | bit key                                           |
   | A256KW        | AES Key Wrap with default initial value using 256 |
   |               | bit key                                           |
   +---------------+---------------------------------------------------+

   An example using this algorithm is shown in Appendix A.3 of [JWE].






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4.5.  Direct Encryption with a Shared Symmetric Key

   This section defines the specifics of directly performing symmetric
   key encryption without performing a key wrapping step.  In this case,
   the shared symmetric key is used directly as the Content Encryption
   Key (CEK) value for the "enc" algorithm.  An empty octet sequence is
   used as the JWE Encrypted Key value.  The "alg" Header Parameter
   value "dir" is used in this case.

   Refer to the security considerations on key lifetimes in Section 8.2
   and AES GCM in Section 8.4 when considering utilizing direct
   encryption.

4.6.  Key Agreement with Elliptic Curve Diffie-Hellman Ephemeral Static
      (ECDH-ES)

   This section defines the specifics of key agreement with Elliptic
   Curve Diffie-Hellman Ephemeral Static [RFC6090], in combination with
   the Concat KDF, as defined in Section 5.8.1 of [NIST.800-56A].  The
   key agreement result can be used in one of two ways:

   1.  directly as the Content Encryption Key (CEK) for the "enc"
       algorithm, in the Direct Key Agreement mode, or

   2.  as a symmetric key used to wrap the CEK with the "A128KW",
       "A192KW", or "A256KW" algorithms, in the Key Agreement with Key
       Wrapping mode.

   A new ephemeral public key value MUST be generated for each key
   agreement operation.

   In Direct Key Agreement mode, the output of the Concat KDF MUST be a
   key of the same length as that used by the "enc" algorithm.  In this
   case, the empty octet sequence is used as the JWE Encrypted Key
   value.  The "alg" Header Parameter value "ECDH-ES" is used in the
   Direct Key Agreement mode.

   In Key Agreement with Key Wrapping mode, the output of the Concat KDF
   MUST be a key of the length needed for the specified key wrapping
   algorithm.  In this case, the JWE Encrypted Key is the CEK wrapped
   with the agreed upon key.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWE Encrypted Key is the result of encrypting the
   CEK using the result of the key agreement algorithm as the key
   encryption key for the corresponding key wrapping algorithm:





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   +----------------+--------------------------------------------------+
   | alg Param      | Key Management Algorithm                         |
   | Value          |                                                  |
   +----------------+--------------------------------------------------+
   | ECDH-ES+A128KW | ECDH-ES using Concat KDF and CEK wrapped with    |
   |                | "A128KW"                                         |
   | ECDH-ES+A192KW | ECDH-ES using Concat KDF and CEK wrapped with    |
   |                | "A192KW"                                         |
   | ECDH-ES+A256KW | ECDH-ES using Concat KDF and CEK wrapped with    |
   |                | "A256KW"                                         |
   +----------------+--------------------------------------------------+

4.6.1.  Header Parameters Used for ECDH Key Agreement

   The following Header Parameter names are used for key agreement as
   defined below.

4.6.1.1.  "epk" (Ephemeral Public Key) Header Parameter

   The "epk" (ephemeral public key) value created by the originator for
   the use in key agreement algorithms.  This key is represented as a
   JSON Web Key [JWK] public key value.  It MUST contain only public key
   parameters and SHOULD contain only the minimum JWK parameters
   necessary to represent the key; other JWK parameters included can be
   checked for consistency and honored or can be ignored.  This Header
   Parameter MUST be present and MUST be understood and processed by
   implementations when these algorithms are used.

4.6.1.2.  "apu" (Agreement PartyUInfo) Header Parameter

   The "apu" (agreement PartyUInfo) value for key agreement algorithms
   using it (such as "ECDH-ES"), represented as a base64url encoded
   string.  When used, the PartyUInfo value contains information about
   the producer.  Use of this Header Parameter is OPTIONAL.  This Header
   Parameter MUST be understood and processed by implementations when
   these algorithms are used.

4.6.1.3.  "apv" (Agreement PartyVInfo) Header Parameter

   The "apv" (agreement PartyVInfo) value for key agreement algorithms
   using it (such as "ECDH-ES"), represented as a base64url encoded
   string.  When used, the PartyVInfo value contains information about
   the recipient.  Use of this Header Parameter is OPTIONAL.  This
   Header Parameter MUST be understood and processed by implementations
   when these algorithms are used.






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4.6.2.  Key Derivation for ECDH Key Agreement

   The key derivation process derives the agreed upon key from the
   shared secret Z established through the ECDH algorithm, per Section
   6.2.2.2 of [NIST.800-56A].

   Key derivation is performed using the Concat KDF, as defined in
   Section 5.8.1 of [NIST.800-56A], where the Digest Method is SHA-256.
   The Concat KDF parameters are set as follows:

   Z
      This is set to the representation of the shared secret Z as an
      octet sequence.

   keydatalen
      This is set to the number of bits in the desired output key.  For
      "ECDH-ES", this is length of the key used by the "enc" algorithm.
      For "ECDH-ES+A128KW", "ECDH-ES+A192KW", and "ECDH-ES+A256KW", this
      is 128, 192, and 256, respectively.

   AlgorithmID
      The AlgorithmID value is of the form Datalen || Data, where Data
      is a variable-length string of zero or more octets, and Datalen is
      a fixed-length, big endian 32 bit counter that indicates the
      length (in octets) of Data.  In the Direct Key Agreement case,
      Data is set to the octets of the ASCII representation of the "enc"
      Header Parameter value.  In the Key Agreement with Key Wrapping
      case, Data is set to the octets of the ASCII representation of the
      "alg" Header Parameter value.

   PartyUInfo
      The PartyUInfo value is of the form Datalen || Data, where Data is
      a variable-length string of zero or more octets, and Datalen is a
      fixed-length, big endian 32 bit counter that indicates the length
      (in octets) of Data.  If an "apu" (agreement PartyUInfo) Header
      Parameter is present, Data is set to the result of base64url
      decoding the "apu" value and Datalen is set to the number of
      octets in Data.  Otherwise, Datalen is set to 0 and Data is set to
      the empty octet sequence.

   PartyVInfo
      The PartyVInfo value is of the form Datalen || Data, where Data is
      a variable-length string of zero or more octets, and Datalen is a
      fixed-length, big endian 32 bit counter that indicates the length
      (in octets) of Data.  If an "apv" (agreement PartyVInfo) Header
      Parameter is present, Data is set to the result of base64url
      decoding the "apv" value and Datalen is set to the number of
      octets in Data.  Otherwise, Datalen is set to 0 and Data is set to



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      the empty octet sequence.

   SuppPubInfo
      This is set to the keydatalen represented as a 32 bit big endian
      integer.

   SuppPrivInfo
      This is set to the empty octet sequence.

   Applications need to specify how the "apu" and "apv" parameters are
   used for that application.  The "apu" and "apv" values MUST be
   distinct, when used.  Applications wishing to conform to
   [NIST.800-56A] need to provide values that meet the requirements of
   that document, e.g., by using values that identify the producer and
   consumer.  Alternatively, applications MAY conduct key derivation in
   a manner similar to The Diffie-Hellman Key Agreement Method
   [RFC2631]: In that case, the "apu" field MAY either be omitted or
   represent a random 512-bit value (analogous to PartyAInfo in
   Ephemeral-Static mode in RFC 2631) and the "apv" field SHOULD NOT be
   present.

   See Appendix C for an example key agreement computation using this
   method.

4.7.  Key Encryption with AES GCM

   This section defines the specifics of encrypting a JWE Content
   Encryption Key (CEK) with Advanced Encryption Standard (AES) in
   Galois/Counter Mode (GCM) [AES, NIST.800-38D].

   Use of an Initialization Vector of size 96 bits is REQUIRED with this
   algorithm.  The Initialization Vector is represented in base64url
   encoded form as the "iv" (initialization vector) Header Parameter
   value.

   The Additional Authenticated Data value used is the empty octet
   string.

   The requested size of the Authentication Tag output MUST be 128 bits,
   regardless of the key size.

   The JWE Encrypted Key value is the Ciphertext output.

   The Authentication Tag output is represented in base64url encoded
   form as the "tag" (authentication tag) Header Parameter value.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWE Encrypted Key is the result of encrypting the



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   CEK using the corresponding algorithm and key size:

     +-----------------+---------------------------------------------+
     | alg Param Value | Key Management Algorithm                    |
     +-----------------+---------------------------------------------+
     | A128GCMKW       | Key wrapping with AES GCM using 128 bit key |
     | A192GCMKW       | Key wrapping with AES GCM using 192 bit key |
     | A256GCMKW       | Key wrapping with AES GCM using 256 bit key |
     +-----------------+---------------------------------------------+

4.7.1.  Header Parameters Used for AES GCM Key Encryption

   The following Header Parameters are used for AES GCM key encryption.

4.7.1.1.  "iv" (Initialization Vector) Header Parameter

   The "iv" (initialization vector) Header Parameter value is the
   base64url encoded representation of the 96 bit Initialization Vector
   value used for the key encryption operation.  This Header Parameter
   MUST be present and MUST be understood and processed by
   implementations when these algorithms are used.

4.7.1.2.  "tag" (Authentication Tag) Header Parameter

   The "tag" (authentication tag) Header Parameter value is the
   base64url encoded representation of the 128 bit Authentication Tag
   value resulting from the key encryption operation.  This Header
   Parameter MUST be present and MUST be understood and processed by
   implementations when these algorithms are used.

4.8.  Key Encryption with PBES2

   This section defines the specifics of performing password-based
   encryption of a JWE CEK, by first deriving a key encryption key from
   a user-supplied password using PBES2 schemes as specified in Section
   6.2 of [RFC2898], then by encrypting the JWE CEK using the derived
   key.

   These algorithms use HMAC SHA-2 algorithms as the Pseudo-Random
   Function (PRF) for the PBKDF2 key derivation and AES Key Wrap
   [RFC3394] for the encryption scheme.  The PBES2 password input is an
   octet sequence; if the password to be used is represented as a text
   string rather than an octet sequence, the UTF-8 encoding of the text
   string MUST be used as the octet sequence.  The salt parameter MUST
   be computed from the "p2s" (PBES2 salt input) Header Parameter value
   and the "alg" (algorithm) Header Parameter value as specified in the
   "p2s" definition below.  The iteration count parameter MUST be
   provided as the "p2c" Header Parameter value.  The algorithms



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   respectively use HMAC SHA-256, HMAC SHA-384, and HMAC SHA-512 as the
   PRF and use 128, 192, and 256 bit AES Key Wrap keys.  Their derived-
   key lengths respectively are 16, 24, and 32 octets.

   The following "alg" (algorithm) Header Parameter values are used to
   indicate that the JWE Encrypted Key is the result of encrypting the
   CEK using the result of the corresponding password-based encryption
   algorithm as the key encryption key for the corresponding key
   wrapping algorithm:

   +--------------------+----------------------------------------------+
   | alg Param Value    | Key Management Algorithm                     |
   +--------------------+----------------------------------------------+
   | PBES2-HS256+A128KW | PBES2 with HMAC SHA-256 and "A128KW"         |
   |                    | wrapping                                     |
   | PBES2-HS384+A192KW | PBES2 with HMAC SHA-384 and "A192KW"         |
   |                    | wrapping                                     |
   | PBES2-HS512+A256KW | PBES2 with HMAC SHA-512 and "A256KW"         |
   |                    | wrapping                                     |
   +--------------------+----------------------------------------------+

   See Appendix C of JSON Web Key (JWK) [JWK] for an example key
   encryption computation using "PBES2-HS256+A128KW".

4.8.1.  Header Parameters Used for PBES2 Key Encryption

   The following Header Parameters are used for Key Encryption with
   PBES2.

4.8.1.1.  "p2s" (PBES2 salt input) Parameter

   The "p2s" (PBES2 salt input) Header Parameter encodes a Salt Input
   value, which is used as part of the PBKDF2 salt value.  The "p2s"
   value is BASE64URL(Salt Input).  This Header Parameter MUST be
   present and MUST be understood and processed by implementations when
   these algorithms are used.

   The salt expands the possible keys that can be derived from a given
   password.  A Salt Input value containing 8 or more octets MUST be
   used.  A new Salt Input value MUST be generated randomly for every
   encryption operation; see RFC 4086 [RFC4086] for considerations on
   generating random values.  The salt value used is (UTF8(Alg) || 0x00
   || Salt Input), where Alg is the "alg" Header Parameter value.

4.8.1.2.  "p2c" (PBES2 count) Parameter

   The "p2c" (PBES2 count) Header Parameter contains the PBKDF2
   iteration count, represented as a positive JSON integer.  This Header



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   Parameter MUST be present and MUST be understood and processed by
   implementations when these algorithms are used.

   The iteration count adds computational expense, ideally compounded by
   the possible range of keys introduced by the salt.  A minimum
   iteration count of 1000 is RECOMMENDED.


5.  Cryptographic Algorithms for Content Encryption

   JWE uses cryptographic algorithms to encrypt and integrity protect
   the Plaintext and to also integrity protect additional authenticated
   data.

5.1.  "enc" (Encryption Algorithm) Header Parameter Values for JWE

   The table below is the set of "enc" (encryption algorithm) Header
   Parameter values that are defined by this specification for use with
   JWE.

   +---------------+----------------------------------+----------------+
   | enc Param     | Content Encryption Algorithm     | Implementation |
   | Value         |                                  | Requirements   |
   +---------------+----------------------------------+----------------+
   | A128CBC-HS256 | AES_128_CBC_HMAC_SHA_256         | Required       |
   |               | authenticated encryption         |                |
   |               | algorithm, as defined in         |                |
   |               | Section 5.2.3                    |                |
   | A192CBC-HS384 | AES_192_CBC_HMAC_SHA_384         | Optional       |
   |               | authenticated encryption         |                |
   |               | algorithm, as defined in         |                |
   |               | Section 5.2.4                    |                |
   | A256CBC-HS512 | AES_256_CBC_HMAC_SHA_512         | Required       |
   |               | authenticated encryption         |                |
   |               | algorithm, as defined in         |                |
   |               | Section 5.2.5                    |                |
   | A128GCM       | AES GCM using 128 bit key        | Recommended    |
   | A192GCM       | AES GCM using 192 bit key        | Optional       |
   | A256GCM       | AES GCM using 256 bit key        | Recommended    |
   +---------------+----------------------------------+----------------+

   All also use a JWE Initialization Vector value and produce JWE
   Ciphertext and JWE Authentication Tag values.

   See Appendix A.3 for a table cross-referencing the JWE "enc"
   (encryption algorithm) values defined in this specification with the
   equivalent identifiers used by other standards and software packages.




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5.2.  AES_CBC_HMAC_SHA2 Algorithms

   This section defines a family of authenticated encryption algorithms
   built using a composition of Advanced Encryption Standard (AES) [AES]
   in Cipher Block Chaining (CBC) mode [NIST.800-38A] with PKCS #7
   padding [RFC5652], Section 6.3 operations and HMAC [RFC2104, SHS]
   operations.  This algorithm family is called AES_CBC_HMAC_SHA2.  It
   also defines three instances of this family, the first using 128 bit
   CBC keys and HMAC SHA-256, the second using 192 bit CBC keys and HMAC
   SHA-384, and the third using 256 bit CBC keys and HMAC SHA-512.  Test
   cases for these algorithms can be found in Appendix B.

   These algorithms are based upon Authenticated Encryption with AES-CBC
   and HMAC-SHA [I-D.mcgrew-aead-aes-cbc-hmac-sha2], performing the same
   cryptographic computations, but with the Initialization Vector and
   Authentication Tag values remaining separate, rather than being
   concatenated with the Ciphertext value in the output representation.
   This option is discussed in Appendix B of that specification.  This
   algorithm family is a generalization of the algorithm family in
   [I-D.mcgrew-aead-aes-cbc-hmac-sha2], and can be used to implement
   those algorithms.

5.2.1.  Conventions Used in Defining AES_CBC_HMAC_SHA2

   We use the following notational conventions.

      CBC-PKCS5-ENC(X, P) denotes the AES CBC encryption of P using PKCS
      #7 padding using the cipher with the key X.

      MAC(Y, M) denotes the application of the Message Authentication
      Code (MAC) to the message M, using the key Y.

5.2.2.  Generic AES_CBC_HMAC_SHA2 Algorithm

   This section defines AES_CBC_HMAC_SHA2 in a manner that is
   independent of the AES CBC key size or hash function to be used.
   Section 5.2.2.1 and Section 5.2.2.2 define the generic encryption and
   decryption algorithms.  Sections 5.2.3 through 5.2.5 define instances
   of AES_CBC_HMAC_SHA2 that specify those details.

5.2.2.1.  AES_CBC_HMAC_SHA2 Encryption

   The authenticated encryption algorithm takes as input four octet
   strings: a secret key K, a plaintext P, additional authenticated data
   A, and an initialization vector IV.  The authenticated ciphertext
   value E and the authentication tag value T are provided as outputs.
   The data in the plaintext are encrypted and authenticated, and the
   additional authenticated data are authenticated, but not encrypted.



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   The encryption process is as follows, or uses an equivalent set of
   steps:

   1.  The secondary keys MAC_KEY and ENC_KEY are generated from the
       input key K as follows.  Each of these two keys is an octet
       string.

          MAC_KEY consists of the initial MAC_KEY_LEN octets of K, in
          order.

          ENC_KEY consists of the final ENC_KEY_LEN octets of K, in
          order.

       The number of octets in the input key K MUST be the sum of
       MAC_KEY_LEN and ENC_KEY_LEN.  The values of these parameters are
       specified by the Authenticated Encryption algorithms in Sections
       5.2.3 through 5.2.5.  Note that the MAC key comes before the
       encryption key in the input key K; this is in the opposite order
       of the algorithm names in the identifier "AES_CBC_HMAC_SHA2".

   2.  The Initialization Vector (IV) used is a 128 bit value generated
       randomly or pseudorandomly for use in the cipher.

   3.  The plaintext is CBC encrypted using PKCS #7 padding using
       ENC_KEY as the key, and the IV.  We denote the ciphertext output
       from this step as E.

   4.  The octet string AL is equal to the number of bits in the
       additional authenticated data A expressed as a 64-bit unsigned
       big endian integer.

   5.  A message authentication tag T is computed by applying HMAC
       [RFC2104] to the following data, in order:

          the additional authenticated data A,

          the initialization vector IV,

          the ciphertext E computed in the previous step, and

          the octet string AL defined above.

       The string MAC_KEY is used as the MAC key.  We denote the output
       of the MAC computed in this step as M. The first T_LEN bits of M
       are used as T.

   6.  The Ciphertext E and the Authentication Tag T are returned as the
       outputs of the authenticated encryption.



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   The encryption process can be illustrated as follows.  Here K, P, A,
   IV, and E denote the key, plaintext, additional authenticated data,
   initialization vector, and ciphertext, respectively.

      MAC_KEY = initial MAC_KEY_LEN octets of K,

      ENC_KEY = final ENC_KEY_LEN octets of K,

      E = CBC-PKCS5-ENC(ENC_KEY, P),

      M = MAC(MAC_KEY, A || IV || E || AL),

      T = initial T_LEN octets of M.

5.2.2.2.  AES_CBC_HMAC_SHA2 Decryption

   The authenticated decryption operation has five inputs: K, A, IV, E,
   and T as defined above.  It has only a single output, either a
   plaintext value P or a special symbol FAIL that indicates that the
   inputs are not authentic.  The authenticated decryption algorithm is
   as follows, or uses an equivalent set of steps:

   1.  The secondary keys MAC_KEY and ENC_KEY are generated from the
       input key K as in Step 1 of Section 5.2.2.1.

   2.  The integrity and authenticity of A and E are checked by
       computing an HMAC with the inputs as in Step 5 of
       Section 5.2.2.1.  The value T, from the previous step, is
       compared to the first MAC_KEY length bits of the HMAC output.  If
       those values are identical, then A and E are considered valid,
       and processing is continued.  Otherwise, all of the data used in
       the MAC validation are discarded, and the Authenticated
       Encryption decryption operation returns an indication that it
       failed, and the operation halts.  (But see Section 11.5 of [JWE]
       for security considerations on thwarting timing attacks.)

   3.  The value E is decrypted and the PKCS #7 padding is checked and
       removed.  The value IV is used as the initialization vector.  The
       value ENC_KEY is used as the decryption key.

   4.  The plaintext value is returned.

5.2.3.  AES_128_CBC_HMAC_SHA_256

   This algorithm is a concrete instantiation of the generic
   AES_CBC_HMAC_SHA2 algorithm above.  It uses the HMAC message
   authentication code [RFC2104] with the SHA-256 hash function [SHS] to
   provide message authentication, with the HMAC output truncated to 128



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   bits, corresponding to the HMAC-SHA-256-128 algorithm defined in
   [RFC4868].  For encryption, it uses AES in the Cipher Block Chaining
   (CBC) mode of operation as defined in Section 6.2 of [NIST.800-38A],
   with PKCS #7 padding and a 128 bit initialization vector (IV) value.

   The AES_CBC_HMAC_SHA2 parameters specific to AES_128_CBC_HMAC_SHA_256
   are:

      The input key K is 32 octets long.

      ENC_KEY_LEN is 16 octets.

      MAC_KEY_LEN is 16 octets.

      The SHA-256 hash algorithm is used for the HMAC.

      The HMAC-SHA-256 output is truncated to T_LEN=16 octets, by
      stripping off the final 16 octets.

5.2.4.  AES_192_CBC_HMAC_SHA_384

   AES_192_CBC_HMAC_SHA_384 is based on AES_128_CBC_HMAC_SHA_256, but
   with the following differences:

      The input key K is 48 octets long instead of 32.

      ENC_KEY_LEN is 24 octets instead of 16.

      MAC_KEY_LEN is 24 octets instead of 16.

      SHA-384 is used for the HMAC instead of SHA-256.

      The HMAC SHA-384 value is truncated to T_LEN=24 octets instead of
      16.

5.2.5.  AES_256_CBC_HMAC_SHA_512

   AES_256_CBC_HMAC_SHA_512 is based on AES_128_CBC_HMAC_SHA_256, but
   with the following differences:

      The input key K is 64 octets long instead of 32.

      ENC_KEY_LEN is 32 octets instead of 16.

      MAC_KEY_LEN is 32 octets instead of 16.

      SHA-512 is used for the HMAC instead of SHA-256.




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      The HMAC SHA-512 value is truncated to T_LEN=32 octets instead of
      16.

5.2.6.  Content Encryption with AES_CBC_HMAC_SHA2

   This section defines the specifics of performing authenticated
   encryption with the AES_CBC_HMAC_SHA2 algorithms.

   The CEK is used as the secret key K.

   The following "enc" (encryption algorithm) Header Parameter values
   are used to indicate that the JWE Ciphertext and JWE Authentication
   Tag values have been computed using the corresponding algorithm:

   +---------------+---------------------------------------------------+
   | enc Param     | Content Encryption Algorithm                      |
   | Value         |                                                   |
   +---------------+---------------------------------------------------+
   | A128CBC-HS256 | AES_128_CBC_HMAC_SHA_256 authenticated encryption |
   |               | algorithm, as defined in Section 5.2.3            |
   | A192CBC-HS384 | AES_192_CBC_HMAC_SHA_384 authenticated encryption |
   |               | algorithm, as defined in Section 5.2.4            |
   | A256CBC-HS512 | AES_256_CBC_HMAC_SHA_512 authenticated encryption |
   |               | algorithm, as defined in Section 5.2.5            |
   +---------------+---------------------------------------------------+

5.3.  Content Encryption with AES GCM

   This section defines the specifics of performing authenticated
   encryption with Advanced Encryption Standard (AES) in Galois/Counter
   Mode (GCM) [AES, NIST.800-38D].

   The CEK is used as the encryption key.

   Use of an initialization vector of size 96 bits is REQUIRED with this
   algorithm.

   The requested size of the Authentication Tag output MUST be 128 bits,
   regardless of the key size.

   The following "enc" (encryption algorithm) Header Parameter values
   are used to indicate that the JWE Ciphertext and JWE Authentication
   Tag values have been computed using the corresponding algorithm and
   key size:







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            +-----------------+------------------------------+
            | enc Param Value | Content Encryption Algorithm |
            +-----------------+------------------------------+
            | A128GCM         | AES GCM using 128 bit key    |
            | A192GCM         | AES GCM using 192 bit key    |
            | A256GCM         | AES GCM using 256 bit key    |
            +-----------------+------------------------------+

   An example using this algorithm is shown in Appendix A.1 of [JWE].


6.  Cryptographic Algorithms for Keys

   A JSON Web Key (JWK) [JWK] is a JSON data structure that represents a
   cryptographic key.  These keys can be either asymmetric or symmetric.
   They can hold both public and private information about the key.
   This section defines the parameters for keys using the algorithms
   specified by this document.

6.1.  "kty" (Key Type) Parameter Values

   The table below is the set of "kty" (key type) parameter values that
   are defined by this specification for use in JWKs.

   +-------------+------------------------------------+----------------+
   | kty Param   | Key Type                           | Implementation |
   | Value       |                                    | Requirements   |
   +-------------+------------------------------------+----------------+
   | EC          | Elliptic Curve [DSS]               | Recommended+   |
   | RSA         | RSA [RFC3447]                      | Required       |
   | oct         | Octet sequence (used to represent  | Required       |
   |             | symmetric keys)                    |                |
   +-------------+------------------------------------+----------------+

   The use of "+" in the Implementation Requirements indicates that the
   requirement strength is likely to be increased in a future version of
   the specification.

6.2.  Parameters for Elliptic Curve Keys

   JWKs can represent Elliptic Curve [DSS] keys.  In this case, the
   "kty" member value is "EC".

6.2.1.  Parameters for Elliptic Curve Public Keys

   An elliptic curve public key is represented by a pair of coordinates
   drawn from a finite field, which together define a point on an
   elliptic curve.  The following members MUST be present for all



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   elliptic curve public keys:

   o  "crv"
   o  "x"

   The following member MUST also be present for elliptic curve public
   keys for the three curves defined in the following section:

   o  "y"

6.2.1.1.  "crv" (Curve) Parameter

   The "crv" (curve) member identifies the cryptographic curve used with
   the key.  Curve values from [DSS] used by this specification are:

   o  "P-256"
   o  "P-384"
   o  "P-521"

   These values are registered in the IANA JSON Web Key Elliptic Curve
   registry defined in Section 7.6.  Additional "crv" values can be
   registered by other specifications.  Specifications registering
   additional curves must define what parameters are used to represent
   keys for the curves registered.  The "crv" value is a case-sensitive
   string.

   SEC1 [SEC1] point compression is not supported for any of these three
   curves.

6.2.1.2.  "x" (X Coordinate) Parameter

   The "x" (x coordinate) member contains the x coordinate for the
   elliptic curve point.  It is represented as the base64url encoding of
   the octet string representation of the coordinate, as defined in
   Section 2.3.5 of SEC1 [SEC1].  The length of this octet string MUST
   be the full size of a coordinate for the curve specified in the "crv"
   parameter.  For example, if the value of "crv" is "P-521", the octet
   string must be 66 octets long.

6.2.1.3.  "y" (Y Coordinate) Parameter

   The "y" (y coordinate) member contains the y coordinate for the
   elliptic curve point.  It is represented as the base64url encoding of
   the octet string representation of the coordinate, as defined in
   Section 2.3.5 of SEC1 [SEC1].  The length of this octet string MUST
   be the full size of a coordinate for the curve specified in the "crv"
   parameter.  For example, if the value of "crv" is "P-521", the octet
   string must be 66 octets long.



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6.2.2.  Parameters for Elliptic Curve Private Keys

   In addition to the members used to represent Elliptic Curve public
   keys, the following member MUST be present to represent Elliptic
   Curve private keys.

6.2.2.1.  "d" (ECC Private Key) Parameter

   The "d" (ECC private key) member contains the Elliptic Curve private
   key value.  It is represented as the base64url encoding of the octet
   string representation of the private key value, as defined in Section
   2.3.7 of SEC1 [SEC1].  The length of this octet string MUST be
   ceiling(log-base-2(n)/8) octets (where n is the order of the curve).

6.3.  Parameters for RSA Keys

   JWKs can represent RSA [RFC3447] keys.  In this case, the "kty"
   member value is "RSA".  The semantics of the parameters defined below
   are the same as those defined in Sections 3.1 and 3.2 of RFC 3447.

6.3.1.  Parameters for RSA Public Keys

   The following members MUST be present for RSA public keys.

6.3.1.1.  "n" (Modulus) Parameter

   The "n" (modulus) member contains the modulus value for the RSA
   public key.  It is represented as a Base64urlUInt encoded value.

   Note that implementers have found that some cryptographic libraries
   prefix an extra zero-valued octet to the modulus representations they
   return, for instance, returning 257 octets for a 2048 bit key, rather
   than 256.  Implementations using such libraries will need to take
   care to omit the extra octet from the base64url encoded
   representation.

6.3.1.2.  "e" (Exponent) Parameter

   The "e" (exponent) member contains the exponent value for the RSA
   public key.  It is represented as a Base64urlUInt encoded value.

   For instance, when representing the value 65537, the octet sequence
   to be base64url encoded MUST consist of the three octets [1, 0, 1];
   the resulting representation for this value is "AQAB".







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6.3.2.  Parameters for RSA Private Keys

   In addition to the members used to represent RSA public keys, the
   following members are used to represent RSA private keys.  The
   parameter "d" is REQUIRED for RSA private keys.  The others enable
   optimizations and SHOULD be included by producers of JWKs
   representing RSA private keys.  If the producer includes any of the
   other private key parameters, then all of the others MUST be present,
   with the exception of "oth", which MUST only be present when more
   than two prime factors were used.

6.3.2.1.  "d" (Private Exponent) Parameter

   The "d" (private exponent) member contains the private exponent value
   for the RSA private key.  It is represented as a Base64urlUInt
   encoded value.

6.3.2.2.  "p" (First Prime Factor) Parameter

   The "p" (first prime factor) member contains the first prime factor.
   It is represented as a Base64urlUInt encoded value.

6.3.2.3.  "q" (Second Prime Factor) Parameter

   The "q" (second prime factor) member contains the second prime
   factor.  It is represented as a Base64urlUInt encoded value.

6.3.2.4.  "dp" (First Factor CRT Exponent) Parameter

   The "dp" (first factor CRT exponent) member contains the Chinese
   Remainder Theorem (CRT) exponent of the first factor.  It is
   represented as a Base64urlUInt encoded value.

6.3.2.5.  "dq" (Second Factor CRT Exponent) Parameter

   The "dq" (second factor CRT exponent) member contains the Chinese
   Remainder Theorem (CRT) exponent of the second factor.  It is
   represented as a Base64urlUInt encoded value.

6.3.2.6.  "qi" (First CRT Coefficient) Parameter

   The "qi" (first CRT coefficient) member contains the Chinese
   Remainder Theorem (CRT) coefficient of the second factor.  It is
   represented as a Base64urlUInt encoded value.







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6.3.2.7.  "oth" (Other Primes Info) Parameter

   The "oth" (other primes info) member contains an array of information
   about any third and subsequent primes, should they exist.  When only
   two primes have been used (the normal case), this parameter MUST be
   omitted.  When three or more primes have been used, the number of
   array elements MUST be the number of primes used minus two.  For more
   information on this case, see the description of the OtherPrimeInfo
   parameters in Section A.1.2 of RFC 3447 [RFC3447], upon which the
   following parameters are modelled.  If the consumer of a JWK does not
   support private keys with more than two primes and it encounters a
   private key that includes the "oth" parameter, then it MUST NOT use
   the key.  Each array element MUST be an object with the following
   members:

6.3.2.7.1.  "r" (Prime Factor)

   The "r" (prime factor) parameter within an "oth" array member
   represents the value of a subsequent prime factor.  It is represented
   as a Base64urlUInt encoded value.

6.3.2.7.2.  "d" (Factor CRT Exponent)

   The "d" (Factor CRT Exponent) parameter within an "oth" array member
   represents the CRT exponent of the corresponding prime factor.  It is
   represented as a Base64urlUInt encoded value.

6.3.2.7.3.  "t" (Factor CRT Coefficient)

   The "t" (factor CRT coefficient) parameter within an "oth" array
   member represents the CRT coefficient of the corresponding prime
   factor.  It is represented as a Base64urlUInt encoded value.

6.4.  Parameters for Symmetric Keys

   When the JWK "kty" member value is "oct" (octet sequence), the member
   "k" is used to represent a symmetric key (or another key whose value
   is a single octet sequence).  An "alg" member SHOULD also be present
   to identify the algorithm intended to be used with the key, unless
   the application uses another means or convention to determine the
   algorithm used.

6.4.1.  "k" (Key Value) Parameter

   The "k" (key value) member contains the value of the symmetric (or
   other single-valued) key.  It is represented as the base64url
   encoding of the octet sequence containing the key value.




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7.  IANA Considerations

   The following registration procedure is used for all the registries
   established by this specification.

   Values are registered on a Specification Required [RFC5226] basis
   after a three-week review period on the jose-reg-review@ietf.org
   mailing list, on the advice of one or more Designated Experts.
   However, to allow for the allocation of values prior to publication,
   the Designated Expert(s) may approve registration once they are
   satisfied that such a specification will be published.

   Registration requests must be sent to the jose-reg-review@ietf.org
   mailing list for review and comment, with an appropriate subject
   (e.g., "Request to register algorithm: example").

   Within the review period, the Designated Expert(s) will either
   approve or deny the registration request, communicating this decision
   to the review list and IANA.  Denials should include an explanation
   and, if applicable, suggestions as to how to make the request
   successful.  Registration requests that are undetermined for a period
   longer than 21 days can be brought to the IESG's attention (using the
   iesg@ietf.org mailing list) for resolution.

   Criteria that should be applied by the Designated Expert(s) includes
   determining whether the proposed registration duplicates existing
   functionality, determining whether it is likely to be of general
   applicability or whether it is useful only for a single application,
   and whether the registration description is clear.

   IANA must only accept registry updates from the Designated Expert(s)
   and should direct all requests for registration to the review mailing
   list.

   It is suggested that multiple Designated Experts be appointed who are
   able to represent the perspectives of different applications using
   this specification, in order to enable broadly-informed review of
   registration decisions.  In cases where a registration decision could
   be perceived as creating a conflict of interest for a particular
   Expert, that Expert should defer to the judgment of the other
   Expert(s).

   [[ Note to the RFC Editor and IANA: Pearl Liang of ICANN had
   requested that the draft supply the following proposed registry
   description information.  It is to be used for all registries
   established by this specification.





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   o  Protocol Category: JSON Object Signing and Encryption (JOSE)

   o  Registry Location: http://www.iana.org/assignments/jose

   o  Webpage Title: (same as the protocol category)

   o  Registry Name: (same as the section title, but excluding the word
      "Registry", for example "JSON Web Signature and Encryption
      Algorithms")

   ]]

7.1.  JSON Web Signature and Encryption Algorithms Registry

   This specification establishes the IANA JSON Web Signature and
   Encryption Algorithms registry for values of the JWS and JWE "alg"
   (algorithm) and "enc" (encryption algorithm) Header Parameters.  The
   registry records the algorithm name, the algorithm usage locations,
   implementation requirements, and a reference to the specification
   that defines it.  The same algorithm name can be registered multiple
   times, provided that the sets of usage locations are disjoint.

   It is suggested that when multiple variations of algorithms are being
   registered that use keys of different lengths and the key lengths for
   each need to be fixed (for instance, because they will be created by
   key derivation functions), that the length of the key be included in
   the algorithm name.  This allows readers of the JSON text to more
   easily make security decisions.

   The Designated Expert(s) should perform reasonable due diligence that
   algorithms being registered are either currently considered
   cryptographically credible or are being registered as Deprecated or
   Prohibited.

   The implementation requirements of an algorithm may be changed over
   time as the cryptographic landscape evolves, for instance, to change
   the status of an algorithm to Deprecated, or to change the status of
   an algorithm from Optional to Recommended+ or Required.  Changes of
   implementation requirements are only permitted on a Specification
   Required basis after review by the Designated Experts(s), with the
   new specification defining the revised implementation requirements
   level.

7.1.1.  Registration Template







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   Algorithm Name:
      The name requested (e.g., "HS256").  This name is a case-sensitive
      ASCII string.  Names may not match other registered names in a
      case-insensitive manner unless the Designated Expert(s) state that
      there is a compelling reason to allow an exception in this
      particular case.

   Algorithm Description:
      Brief description of the Algorithm (e.g., "HMAC using SHA-256").

   Algorithm Usage Location(s):
      The algorithm usage location.  This must be one or more of the
      values "alg" or "enc" if the algorithm is to be used with JWS or
      JWE.  The value "JWK" is used if the algorithm identifier will be
      used as a JWK "alg" member value, but will not be used with JWS or
      JWE; this could be the case, for instance, for non-authenticated
      encryption algorithms.  Other values may be used with the approval
      of a Designated Expert.

   JOSE Implementation Requirements:
      The algorithm implementation requirements for JWS and JWE, which
      must be one the words Required, Recommended, Optional, Deprecated,
      or Prohibited.  Optionally, the word can be followed by a "+" or
      "-".  The use of "+" indicates that the requirement strength is
      likely to be increased in a future version of the specification.
      The use of "-" indicates that the requirement strength is likely
      to be decreased in a future version of the specification.  Any
      identifiers registered for non-authenticated encryption algorithms
      or other algorithms that are otherwise unsuitable for direct use
      as JWS or JWE algorithms must be registered as "Prohibited".

   Change Controller:
      For Standards Track RFCs, state "IESG".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      email address, home page URI) may also be included.

   Specification Document(s):
      Reference to the document(s) that specify the parameter,
      preferably including URI(s) that can be used to retrieve copies of
      the document(s).  An indication of the relevant sections may also
      be included but is not required.

   Algorithm Analysis Documents(s):
      References to publication(s) in well-known cryptographic
      conferences, by national standards bodies, or by other
      authoritative sources analyzing the cryptographic soundness of the
      algorithm to be registered.  The designated experts may require
      convincing evidence of the cryptographic soundness of a new



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      algorithm to be provided with the registration request unless the
      algorithm is being registered as Deprecated or Prohibited.  Having
      gone through working group and IETF review, the initial
      registrations made by this document are exempt from the need to
      provide this information.

7.1.2.  Initial Registry Contents

   o  Algorithm Name: "HS256"
   o  Algorithm Description: HMAC using SHA-256
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Required
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "HS384"
   o  Algorithm Description: HMAC using SHA-384
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "HS512"
   o  Algorithm Description: HMAC using SHA-512
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "RS256"
   o  Algorithm Description: RSASSA-PKCS-v1_5 using SHA-256
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "RS384"
   o  Algorithm Description: RSASSA-PKCS-v1_5 using SHA-384
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]





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   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "RS512"
   o  Algorithm Description: RSASSA-PKCS-v1_5 using SHA-512
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "ES256"
   o  Algorithm Description: ECDSA using P-256 and SHA-256
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended+
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "ES384"
   o  Algorithm Description: ECDSA using P-384 and SHA-384
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "ES512"
   o  Algorithm Description: ECDSA using P-521 and SHA-512
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "PS256"
   o  Algorithm Description: RSASSA-PSS using SHA-256 and MGF1 with SHA-
      256
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "PS384"
   o  Algorithm Description: RSASSA-PSS using SHA-384 and MGF1 with SHA-
      384





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   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "PS512"
   o  Algorithm Description: RSASSA-PSS using SHA-512 and MGF1 with SHA-
      512
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "none"
   o  Algorithm Description: No digital signature or MAC performed
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 3.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "RSA1_5"
   o  Algorithm Description: RSAES-PKCS1-V1_5
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended-
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "RSA-OAEP"
   o  Algorithm Description: RSAES OAEP using default parameters
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended+
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "RSA-OAEP-256"
   o  Algorithm Description: RSAES OAEP using SHA-256 and MGF1 with SHA-
      256
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]





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   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A128KW"
   o  Algorithm Description: AES Key Wrap using 128 bit key
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A192KW"
   o  Algorithm Description: AES Key Wrap using 192 bit key
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A256KW"
   o  Algorithm Description: AES Key Wrap using 256 bit key
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "dir"
   o  Algorithm Description: Direct use of a shared symmetric key
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "ECDH-ES"
   o  Algorithm Description: ECDH-ES using Concat KDF
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended+
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "ECDH-ES+A128KW"
   o  Algorithm Description: ECDH-ES using Concat KDF and "A128KW"
      wrapping
   o  Algorithm Usage Location(s): "alg"





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   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "ECDH-ES+A192KW"
   o  Algorithm Description: ECDH-ES using Concat KDF and "A192KW"
      wrapping
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "ECDH-ES+A256KW"
   o  Algorithm Description: ECDH-ES using Concat KDF and "A256KW"
      wrapping
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A128GCMKW"
   o  Algorithm Description: Key wrapping with AES GCM using 128 bit key
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.7 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A192GCMKW"
   o  Algorithm Description: Key wrapping with AES GCM using 192 bit key
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.7 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A256GCMKW"
   o  Algorithm Description: Key wrapping with AES GCM using 256 bit key
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.7 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a





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   o  Algorithm Name: "PBES2-HS256+A128KW"
   o  Algorithm Description: PBES2 with HMAC SHA-256 and "A128KW"
      wrapping
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.8 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "PBES2-HS384+A192KW"
   o  Algorithm Description: PBES2 with HMAC SHA-384 and "A192KW"
      wrapping
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.8 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "PBES2-HS512+A256KW"
   o  Algorithm Description: PBES2 with HMAC SHA-512 and "A256KW"
      wrapping
   o  Algorithm Usage Location(s): "alg"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.8 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A128CBC-HS256"
   o  Algorithm Description: AES_128_CBC_HMAC_SHA_256 authenticated
      encryption algorithm
   o  Algorithm Usage Location(s): "enc"
   o  JOSE Implementation Requirements: Required
   o  Change Controller: IESG
   o  Specification Document(s): Section 5.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A192CBC-HS384"
   o  Algorithm Description: AES_192_CBC_HMAC_SHA_384 authenticated
      encryption algorithm
   o  Algorithm Usage Location(s): "enc"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 5.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A256CBC-HS512"





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   o  Algorithm Description: AES_256_CBC_HMAC_SHA_512 authenticated
      encryption algorithm
   o  Algorithm Usage Location(s): "enc"
   o  JOSE Implementation Requirements: Required
   o  Change Controller: IESG
   o  Specification Document(s): Section 5.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A128GCM"
   o  Algorithm Description: AES GCM using 128 bit key
   o  Algorithm Usage Location(s): "enc"
   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 5.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A192GCM"
   o  Algorithm Description: AES GCM using 192 bit key
   o  Algorithm Usage Location(s): "enc"
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 5.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

   o  Algorithm Name: "A256GCM"
   o  Algorithm Description: AES GCM using 256 bit key
   o  Algorithm Usage Location(s): "enc"
   o  JOSE Implementation Requirements: Recommended
   o  Change Controller: IESG
   o  Specification Document(s): Section 5.1 of [[ this document ]]
   o  Algorithm Analysis Documents(s): n/a

7.2.  Header Parameter Names Registration

   This specification registers the Header Parameter names defined in
   Section 4.6.1, Section 4.7.1, and Section 4.8.1 in the IANA JSON Web
   Signature and Encryption Header Parameters registry defined in [JWS].

7.2.1.  Registry Contents

   o  Header Parameter Name: "epk"
   o  Header Parameter Description: Ephemeral Public Key
   o  Header Parameter Usage Location(s): JWE
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.6.1.1 of [[ this document ]]






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   o  Header Parameter Name: "apu"
   o  Header Parameter Description: Agreement PartyUInfo
   o  Header Parameter Usage Location(s): JWE
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.6.1.2 of [[ this document ]]

   o  Header Parameter Name: "apv"
   o  Header Parameter Description: Agreement PartyVInfo
   o  Header Parameter Usage Location(s): JWE
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.6.1.3 of [[ this document ]]

   o  Header Parameter Name: "iv"
   o  Header Parameter Description: Initialization Vector
   o  Header Parameter Usage Location(s): JWE
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.7.1.1 of [[ this document ]]

   o  Header Parameter Name: "tag"
   o  Header Parameter Description: Authentication Tag
   o  Header Parameter Usage Location(s): JWE
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.7.1.2 of [[ this document ]]

   o  Header Parameter Name: "p2s"
   o  Header Parameter Description: PBES2 salt
   o  Header Parameter Usage Location(s): JWE
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.8.1.1 of [[ this document ]]

   o  Header Parameter Name: "p2c"
   o  Header Parameter Description: PBES2 count
   o  Header Parameter Usage Location(s): JWE
   o  Change Controller: IESG
   o  Specification Document(s): Section 4.8.1.2 of [[ this document ]]

7.3.  JSON Web Encryption Compression Algorithms Registry

   This specification establishes the IANA JSON Web Encryption
   Compression Algorithms registry for JWE "zip" member values.  The
   registry records the compression algorithm value and a reference to
   the specification that defines it.

7.3.1.  Registration Template







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   Compression Algorithm Value:
      The name requested (e.g., "DEF").  Because a core goal of this
      specification is for the resulting representations to be compact,
      it is RECOMMENDED that the name be short -- not to exceed 8
      characters without a compelling reason to do so.  This name is
      case-sensitive.  Names may not match other registered names in a
      case-insensitive manner unless the Designated Expert(s) state that
      there is a compelling reason to allow an exception in this
      particular case.

   Compression Algorithm Description:
      Brief description of the compression algorithm (e.g., "DEFLATE").

   Change Controller:
      For Standards Track RFCs, state "IESG".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      email address, home page URI) may also be included.

   Specification Document(s):
      Reference to the document(s) that specify the parameter,
      preferably including URI(s) that can be used to retrieve copies of
      the document(s).  An indication of the relevant sections may also
      be included but is not required.

7.3.2.  Initial Registry Contents

   o  Compression Algorithm Value: "DEF"
   o  Compression Algorithm Description: DEFLATE
   o  Change Controller: IESG
   o  Specification Document(s): JSON Web Encryption (JWE) [JWE]

7.4.  JSON Web Key Types Registry

   This specification establishes the IANA JSON Web Key Types registry
   for values of the JWK "kty" (key type) parameter.  The registry
   records the "kty" value, implementation requirements, and a reference
   to the specification that defines it.

   The implementation requirements of a key type may be changed over
   time as the cryptographic landscape evolves, for instance, to change
   the status of a key type to Deprecated, or to change the status of a
   key type from Optional to Recommended+ or Required.  Changes of
   implementation requirements are only permitted on a Specification
   Required basis after review by the Designated Experts(s), with the
   new specification defining the revised implementation requirements
   level.





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7.4.1.  Registration Template

   "kty" Parameter Value:
      The name requested (e.g., "EC").  Because a core goal of this
      specification is for the resulting representations to be compact,
      it is RECOMMENDED that the name be short -- not to exceed 8
      characters without a compelling reason to do so.  This name is
      case-sensitive.  Names may not match other registered names in a
      case-insensitive manner unless the Designated Expert(s) state that
      there is a compelling reason to allow an exception in this
      particular case.

   Key Type Description:
      Brief description of the Key Type (e.g., "Elliptic Curve").

   Change Controller:
      For Standards Track RFCs, state "IESG".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      email address, home page URI) may also be included.

   JOSE Implementation Requirements:
      The key type implementation requirements for JWS and JWE, which
      must be one the words Required, Recommended, Optional, Deprecated,
      or Prohibited.  Optionally, the word can be followed by a "+" or
      "-".  The use of "+" indicates that the requirement strength is
      likely to be increased in a future version of the specification.
      The use of "-" indicates that the requirement strength is likely
      to be decreased in a future version of the specification.

   Specification Document(s):
      Reference to the document(s) that specify the parameter,
      preferably including URI(s) that can be used to retrieve copies of
      the document(s).  An indication of the relevant sections may also
      be included but is not required.

7.4.2.  Initial Registry Contents

   This specification registers the values defined in Section 6.1.

   o  "kty" Parameter Value: "EC"
   o  Key Type Description: Elliptic Curve
   o  JOSE Implementation Requirements: Recommended+
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2 of [[ this document ]]

   o  "kty" Parameter Value: "RSA"





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   o  Key Type Description: RSA
   o  JOSE Implementation Requirements: Required
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3 of [[ this document ]]

   o  "kty" Parameter Value: "oct"
   o  Key Type Description: Octet sequence
   o  JOSE Implementation Requirements: Required
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.4 of [[ this document ]]

7.5.  JSON Web Key Parameters Registration

   This specification registers the parameter names defined in Sections
   6.2, 6.3, and 6.4 in the IANA JSON Web Key Parameters registry
   defined in [JWK].

7.5.1.  Registry Contents

   o  Parameter Name: "crv"
   o  Parameter Description: Curve
   o  Used with "kty" Value(s): "EC"
   o  Parameter Information Class: Public
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2.1.1 of [[ this document ]]

   o  Parameter Name: "x"
   o  Parameter Description: X Coordinate
   o  Used with "kty" Value(s): "EC"
   o  Parameter Information Class: Public
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2.1.2 of [[ this document ]]

   o  Parameter Name: "y"
   o  Parameter Description: Y Coordinate
   o  Used with "kty" Value(s): "EC"
   o  Parameter Information Class: Public
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2.1.3 of [[ this document ]]

   o  Parameter Name: "d"
   o  Parameter Description: ECC Private Key
   o  Used with "kty" Value(s): "EC"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2.2.1 of [[ this document ]]





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   o  Parameter Name: "n"
   o  Parameter Description: Modulus
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Public
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.1.1 of [[ this document ]]

   o  Parameter Name: "e"
   o  Parameter Description: Exponent
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Public
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.1.2 of [[ this document ]]

   o  Parameter Name: "d"
   o  Parameter Description: Private Exponent
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.2.1 of [[ this document ]]

   o  Parameter Name: "p"
   o  Parameter Description: First Prime Factor
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.2.2 of [[ this document ]]

   o  Parameter Name: "q"
   o  Parameter Description: Second Prime Factor
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.2.3 of [[ this document ]]

   o  Parameter Name: "dp"
   o  Parameter Description: First Factor CRT Exponent
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.2.4 of [[ this document ]]

   o  Parameter Name: "dq"
   o  Parameter Description: Second Factor CRT Exponent
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Private





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   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.2.5 of [[ this document ]]

   o  Parameter Name: "qi"
   o  Parameter Description: First CRT Coefficient
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.2.6 of [[ this document ]]

   o  Parameter Name: "oth"
   o  Parameter Description: Other Primes Info
   o  Used with "kty" Value(s): "RSA"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.3.2.7 of [[ this document ]]

   o  Parameter Name: "k"
   o  Parameter Description: Key Value
   o  Used with "kty" Value(s): "oct"
   o  Parameter Information Class: Private
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.4.1 of [[ this document ]]

7.6.  JSON Web Key Elliptic Curve Registry

   This specification establishes the IANA JSON Web Key Elliptic Curve
   registry for JWK "crv" member values.  The registry records the curve
   name, implementation requirements, and a reference to the
   specification that defines it.  This specification registers the
   parameter names defined in Section 6.2.1.1.

   The implementation requirements of a curve may be changed over time
   as the cryptographic landscape evolves, for instance, to change the
   status of a curve to Deprecated, or to change the status of a curve
   from Optional to Recommended+ or Required.  Changes of implementation
   requirements are only permitted on a Specification Required basis
   after review by the Designated Experts(s), with the new specification
   defining the revised implementation requirements level.

7.6.1.  Registration Template

   Curve Name:
      The name requested (e.g., "P-256").  Because a core goal of this
      specification is for the resulting representations to be compact,
      it is RECOMMENDED that the name be short -- not to exceed 8
      characters without a compelling reason to do so.  This name is
      case-sensitive.  Names may not match other registered names in a



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      case-insensitive manner unless the Designated Expert(s) state that
      there is a compelling reason to allow an exception in this
      particular case.

   Curve Description:
      Brief description of the curve (e.g., "P-256 curve").

   JOSE Implementation Requirements:
      The curve implementation requirements for JWS and JWE, which must
      be one the words Required, Recommended, Optional, Deprecated, or
      Prohibited.  Optionally, the word can be followed by a "+" or "-".
      The use of "+" indicates that the requirement strength is likely
      to be increased in a future version of the specification.  The use
      of "-" indicates that the requirement strength is likely to be
      decreased in a future version of the specification.

   Change Controller:
      For Standards Track RFCs, state "IESG".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      email address, home page URI) may also be included.

   Specification Document(s):
      Reference to the document(s) that specify the parameter,
      preferably including URI(s) that can be used to retrieve copies of
      the document(s).  An indication of the relevant sections may also
      be included but is not required.

7.6.2.  Initial Registry Contents

   o  Curve Name: "P-256"
   o  Curve Description: P-256 curve
   o  JOSE Implementation Requirements: Recommended+
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2.1.1 of [[ this document ]]

   o  Curve Name: "P-384"
   o  Curve Description: P-384 curve
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2.1.1 of [[ this document ]]

   o  Curve Name: "P-521"
   o  Curve Description: P-521 curve
   o  JOSE Implementation Requirements: Optional
   o  Change Controller: IESG
   o  Specification Document(s): Section 6.2.1.1 of [[ this document ]]





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8.  Security Considerations

   All of the security issues that are pertinent to any cryptographic
   application must be addressed by JWS/JWE/JWK agents.  Among these
   issues are protecting the user's asymmetric private and symmetric
   secret keys and employing countermeasures to various attacks.

   The security considerations in [AES], [DSS], [JWE], [JWK], [JWS],
   [NIST.800-38D], [NIST.800-56A], [NIST.800-107], [RFC2104], [RFC3394],
   [RFC3447], [RFC5116], [RFC6090], and [SHS] apply to this
   specification.

8.1.  Cryptographic Agility

   Implementers should be aware that cryptographic algorithms become
   weaker with time.  As new cryptanalysis techniques are developed and
   computing performance improves, the work factor to break a particular
   cryptographic algorithm will be reduced.  Therefore, implementers and
   deployments must be prepared for the set of algorithms that are
   supported and used to change over time.  Thus, cryptographic
   algorithm implementations should be modular, allowing new algorithms
   to be readily inserted.

8.2.  Key Lifetimes

   Many algorithms have associated security considerations related to
   key lifetimes and/or the number of times that a key may be used.
   Those security considerations continue to apply when using those
   algorithms with JOSE data structures.  See NIST SP 800-57
   [NIST.800-57] for specific guidance on key lifetimes.

8.3.  RSAES-PKCS1-v1_5 Security Considerations

   While Section 8 of RFC 3447 [RFC3447] explicitly calls for people not
   to adopt RSASSA-PKCS-v1_5 for new applications and instead requests
   that people transition to RSASSA-PSS, this specification does include
   RSASSA-PKCS-v1_5, for interoperability reasons, because it is
   commonly implemented.

   Keys used with RSAES-PKCS1-v1_5 must follow the constraints in
   Section 7.2 of RFC 3447.  Also, keys with a low public key exponent
   value, as described in Section 3 of Twenty years of attacks on the
   RSA cryptosystem [Boneh99], must not be used.

8.4.  AES GCM Security Considerations

   Keys used with AES GCM must follow the constraints in Section 8.3 of
   [NIST.800-38D], which states: "The total number of invocations of the



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   authenticated encryption function shall not exceed 2^32, including
   all IV lengths and all instances of the authenticated encryption
   function with the given key".  In accordance with this rule, AES GCM
   MUST NOT be used with the same key value more than 2^32 times.

   An Initialization Vector value MUST NOT ever be used multiple times
   with the same AES GCM key.  One way to prevent this is to store a
   counter with the key and increment it with every use.  The counter
   can also be used to prevent exceeding the 2^32 limit above.

   This security consideration does not apply to the composite AES-CBC
   HMAC SHA-2 or AES Key Wrap algorithms.

8.5.  Unsecured JWS Security Considerations

   Unsecured JWSs (JWSs that use the "alg" value "none") provide no
   integrity protection.  Thus, they must only be used in contexts in
   which the payload is secured by means other than a digital signature
   or MAC value, or need not be secured.

   An example means of preventing accepting Unsecured JWSs by default is
   for the "verify" method of a hypothetical JWS software library to
   have a Boolean "acceptUnsecured" parameter that indicates "none" is
   an acceptable "alg" value.  As another example, the "verify" method
   might take a list of algorithms that are acceptable to the
   application as a parameter and would reject Unsecured JWS values if
   "none" is not in that list.

   The following example illustrates the reasons for not accepting
   Unsecured JWSs at a global level.  Suppose an application accepts
   JWSs over two channels, (1) HTTP and (2) HTTPS with client
   authentication.  It requires a JWS signature on objects received over
   HTTP, but accepts Unsecured JWSs over HTTPS.  If the application were
   to globally indicate that "none" is acceptable, then an attacker
   could provide it with an Unsecured JWS over HTTP and still have that
   object successfully validate.  Instead, the application needs to
   indicate acceptance of "none" for each object received over HTTPS
   (e.g., by setting "acceptUnsecured" to "true" for the first
   hypothetical JWS software library above), but not for each object
   received over HTTP.

8.6.  Denial of Service Attacks

   Receiving agents that validate signatures and sending agents that
   encrypt messages need to be cautious of cryptographic processing
   usage when validating signatures and encrypting messages using keys
   larger than those mandated in this specification.  An attacker could
   supply content using keys that would result in excessive



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   cryptographic processing, for example, keys larger than those
   mandated in this specification.  Implementations should set and
   enforce upper limits on the key sizes they accept.  Section 5.6.1
   (Comparable Algorithm Strengths) of NIST SP 800-57 [NIST.800-57]
   contains statements on largest approved key sizes that may be
   applicable.

8.7.  Reusing Key Material when Encrypting Keys

   It is NOT RECOMMENDED to reuse the same entire set of key material
   (Key Encryption Key, Content Encryption Key, Initialization Vector,
   etc.) to encrypt multiple JWK or JWK Set objects, or to encrypt the
   same JWK or JWK Set object multiple times.  One suggestion for
   preventing re-use is to always generate at least one new piece of key
   material for each encryption operation (e.g., a new Content
   Encryption Key, a new Initialization Vector, and/or a new PBES2
   Salt), based on the considerations noted in this document as well as
   from RFC 4086 [RFC4086].

8.8.  Password Considerations

   Passwords are vulnerable to a number of attacks.  To help mitigate
   some of these limitations, this document applies principles from RFC
   2898 [RFC2898] to derive cryptographic keys from user-supplied
   passwords.

   However, the strength of the password still has a significant impact.
   A high-entropy password has greater resistance to dictionary attacks.
   [NIST.800-63-1] contains guidelines for estimating password entropy,
   which can help applications and users generate stronger passwords.

   An ideal password is one that is as large as (or larger than) the
   derived key length.  However, passwords larger than a certain
   algorithm-specific size are first hashed, which reduces an attacker's
   effective search space to the length of the hash algorithm.  It is
   RECOMMENDED that a password used for "PBES2-HS256+A128KW" be no
   shorter than 16 octets and no longer than 128 octets and a password
   used for "PBES2-HS512+A256KW" be no shorter than 32 octets and no
   longer than 128 octets long.

   Still, care needs to be taken in where and how password-based
   encryption is used.  These algorithms can still be susceptible to
   dictionary-based attacks if the iteration count is too small; this is
   of particular concern if these algorithms are used to protect data
   that an attacker can have indefinite number of attempts to circumvent
   the protection, such as protected data stored on a file system.





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8.9.  Key Entropy and Random Values

   See Section 10.1 of [JWS] for security considerations on key entropy
   and random values.

8.10.  Differences between Digital Signatures and MACs

   See Section 10.5 of [JWS] for security considerations on differences
   between digital signatures and MACs.

8.11.  Using Matching Algorithm Strengths

   See Section 11.3 of [JWE] for security considerations on using
   matching algorithm strengths.

8.12.  Adaptive Chosen-Ciphertext Attacks

   See Section 11.4 of [JWE] for security considerations on adaptive
   chosen-ciphertext attacks.

8.13.  Timing Attacks

   See Section 10.9 of [JWS] and Section 11.5 of [JWE] for security
   considerations on timing attacks.

8.14.  RSA Private Key Representations and Blinding

   See Section 9.3 of [JWK] for security considerations on RSA private
   key representations and blinding.


9.  Internationalization Considerations

   Passwords obtained from users are likely to require preparation and
   normalization to account for differences of octet sequences generated
   by different input devices, locales, etc.  It is RECOMMENDED that
   applications to perform the steps outlined in
   [I-D.ietf-precis-saslprepbis] to prepare a password supplied directly
   by a user before performing key derivation and encryption.


10.  References

10.1.  Normative References

   [AES]      National Institute of Standards and Technology (NIST),
              "Advanced Encryption Standard (AES)", FIPS PUB 197,
              November 2001.



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   [Boneh99]  "Twenty years of attacks on the RSA cryptosystem", Notices
              of the American Mathematical Society (AMS), Vol. 46, No.
              2, pp. 203-213 http://crypto.stanford.edu/~dabo/pubs/
              papers/RSA-survey.pdf, 1999.

   [DSS]      National Institute of Standards and Technology, "Digital
              Signature Standard (DSS)", FIPS PUB 186-4, July 2013.

   [JWE]      Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              draft-ietf-jose-json-web-encryption (work in progress),
              January 2015.

   [JWK]      Jones, M., "JSON Web Key (JWK)",
              draft-ietf-jose-json-web-key (work in progress),
              January 2015.

   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", draft-ietf-jose-json-web-signature (work
              in progress), January 2015.

   [NIST.800-38A]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Block Cipher Modes of Operation",
              NIST PUB 800-38A, December 2001.

   [NIST.800-38D]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Block Cipher Modes of Operation:
              Galois/Counter Mode (GCM) and GMAC", NIST PUB 800-38D,
              December 2001.

   [NIST.800-56A]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Pair-Wise Key Establishment Schemes
              Using Discrete Logarithm Cryptography", NIST Special
              Publication 800-56A, Revision 2, May 2013.

   [NIST.800-57]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Key Management - Part 1: General
              (Revision 3)", NIST Special Publication 800-57, Part 1,
              Revision 3, July 2012.

   [RFC20]    Cerf, V., "ASCII format for Network Interchange", RFC 20,
              October 1969.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,



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              February 1997.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2898]  Kaliski, B., "PKCS #5: Password-Based Cryptography
              Specification Version 2.0", RFC 2898, September 2000.

   [RFC3394]  Schaad, J. and R. Housley, "Advanced Encryption Standard
              (AES) Key Wrap Algorithm", RFC 3394, September 2002.

   [RFC3447]  Jonsson, J. and B. Kaliski, "Public-Key Cryptography
              Standards (PKCS) #1: RSA Cryptography Specifications
              Version 2.1", RFC 3447, February 2003.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
              384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              RFC 4949, August 2007.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, September 2009.

   [RFC6090]  McGrew, D., Igoe, K., and M. Salter, "Fundamental Elliptic
              Curve Cryptography Algorithms", RFC 6090, February 2011.

   [RFC7159]  Bray, T., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, March 2014.

   [SEC1]     Standards for Efficient Cryptography Group, "SEC 1:
              Elliptic Curve Cryptography", Version 2.0, May 2009.

   [SHS]      National Institute of Standards and Technology, "Secure
              Hash Standard (SHS)", FIPS PUB 180-4, March 2012.

   [UNICODE]  The Unicode Consortium, "The Unicode Standard", 1991-,
              <http://www.unicode.org/versions/latest/>.

10.2.  Informative References

   [CanvasApp]
              Facebook, "Canvas Applications", 2010.

   [I-D.ietf-precis-saslprepbis]



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              Saint-Andre, P. and A. Melnikov, "Preparation,
              Enforcement, and Comparison of Internationalized Strings
              Representing Usernames and Passwords",
              draft-ietf-precis-saslprepbis-13 (work in progress),
              December 2014.

   [I-D.mcgrew-aead-aes-cbc-hmac-sha2]
              McGrew, D., Foley, J., and K. Paterson, "Authenticated
              Encryption with AES-CBC and HMAC-SHA",
              draft-mcgrew-aead-aes-cbc-hmac-sha2-05 (work in progress),
              July 2014.

   [I-D.miller-jose-jwe-protected-jwk]
              Miller, M., "Using JavaScript Object Notation (JSON) Web
              Encryption (JWE) for Protecting JSON Web Key (JWK)
              Objects", draft-miller-jose-jwe-protected-jwk-02 (work in
              progress), June 2013.

   [I-D.rescorla-jsms]
              Rescorla, E. and J. Hildebrand, "JavaScript Message
              Security Format", draft-rescorla-jsms-00 (work in
              progress), March 2011.

   [JCA]      Oracle, "Java Cryptography Architecture (JCA) Reference
              Guide", 2014.

   [JSE]      Bradley, J. and N. Sakimura (editor), "JSON Simple
              Encryption", September 2010.

   [JSS]      Bradley, J. and N. Sakimura (editor), "JSON Simple Sign",
              September 2010.

   [MagicSignatures]
              Panzer (editor), J., Laurie, B., and D. Balfanz, "Magic
              Signatures", January 2011.

   [NIST.800-107]
              National Institute of Standards and Technology (NIST),
              "Recommendation for Applications Using Approved Hash
              Algorithms", NIST Special Publication 800-107, Revision 1,
              August 2012.

   [NIST.800-63-1]
              National Institute of Standards and Technology (NIST),
              "Electronic Authentication Guideline", NIST Special
              Publication 800-63-1, December 2011.

   [RFC2631]  Rescorla, E., "Diffie-Hellman Key Agreement Method",



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              RFC 2631, June 1999.

   [RFC3275]  Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup
              Language) XML-Signature Syntax and Processing", RFC 3275,
              March 2002.

   [RFC4086]  Eastlake, D., Schiller, J., and S. Crocker, "Randomness
              Requirements for Security", BCP 106, RFC 4086, June 2005.

   [RFC5116]  McGrew, D., "An Interface and Algorithms for Authenticated
              Encryption", RFC 5116, January 2008.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [W3C.NOTE-xmldsig-core2-20130411]
              Eastlake, D., Reagle, J., Solo, D., Hirsch, F., Roessler,
              T., Yiu, K., Datta, P., and S. Cantor, "XML Signature
              Syntax and Processing Version 2.0", World Wide Web
              Consortium Note NOTE-xmldsig-core2-20130411, April 2013,
              <http://www.w3.org/TR/2013/NOTE-xmldsig-core2-20130411/>.

   [W3C.REC-xmlenc-core-20021210]
              Eastlake, D. and J. Reagle, "XML Encryption Syntax and
              Processing", World Wide Web Consortium Recommendation REC-
              xmlenc-core-20021210, December 2002,
              <http://www.w3.org/TR/2002/REC-xmlenc-core-20021210>.

   [W3C.REC-xmlenc-core1-20130411]
              Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler,
              "XML Encryption Syntax and Processing Version 1.1", World
              Wide Web Consortium Recommendation REC-xmlenc-core1-
              20130411, April 2013,
              <http://www.w3.org/TR/2013/REC-xmlenc-core1-20130411/>.


Appendix A.  Algorithm Identifier Cross-Reference

   This appendix contains tables cross-referencing the cryptographic
   algorithm identifier values defined in this specification with the
   equivalent identifiers used by other standards and software packages.
   See XML DSIG [RFC3275], XML DSIG 2.0
   [W3C.NOTE-xmldsig-core2-20130411], XML Encryption
   [W3C.REC-xmlenc-core-20021210], XML Encryption 1.1
   [W3C.REC-xmlenc-core1-20130411], and Java Cryptography Architecture
   [JCA] for more information about the names defined by those
   documents.



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A.1.  Digital Signature/MAC Algorithm Identifier Cross-Reference

   This section contains a table cross-referencing the JWS digital
   signature and MAC "alg" (algorithm) values defined in this
   specification with the equivalent identifiers used by other standards
   and software packages.

   +-------+------------------------------+-------------+--------------+
   | JWS   | XML DSIG                     | JCA         | OID          |
   +-------+------------------------------+-------------+--------------+
   | HS256 | http://www.w3.org/2001/04/xm | HmacSHA256  | 1.2.840.1135 |
   |       | ldsig-more#hmac-sha256       |             | 49.2.9       |
   | HS384 | http://www.w3.org/2001/04/xm | HmacSHA384  | 1.2.840.1135 |
   |       | ldsig-more#hmac-sha384       |             | 49.2.10      |
   | HS512 | http://www.w3.org/2001/04/xm | HmacSHA512  | 1.2.840.1135 |
   |       | ldsig-more#hmac-sha512       |             | 49.2.11      |
   | RS256 | http://www.w3.org/2001/04/xm | SHA256withR | 1.2.840.1135 |
   |       | ldsig-more#rsa-sha256        | SA          | 49.1.1.11    |
   | RS384 | http://www.w3.org/2001/04/xm | SHA384withR | 1.2.840.1135 |
   |       | ldsig-more#rsa-sha384        | SA          | 49.1.1.12    |
   | RS512 | http://www.w3.org/2001/04/xm | SHA512withR | 1.2.840.1135 |
   |       | ldsig-more#rsa-sha512        | SA          | 49.1.1.13    |
   | ES256 | http://www.w3.org/2001/04/xm | SHA256withE | 1.2.840.1004 |
   |       | ldsig-more#ecdsa-sha256      | CDSA        | 5.4.3.2      |
   | ES384 | http://www.w3.org/2001/04/xm | SHA384withE | 1.2.840.1004 |
   |       | ldsig-more#ecdsa-sha384      | CDSA        | 5.4.3.3      |
   | ES512 | http://www.w3.org/2001/04/xm | SHA512withE | 1.2.840.1004 |
   |       | ldsig-more#ecdsa-sha512      | CDSA        | 5.4.3.4      |
   | PS256 | http://www.w3.org/2007/05/xm | SHA256withR | 1.2.840.1135 |
   |       | ldsig-more#sha256-rsa-MGF1   | SAandMGF1   | 49.1.1.10    |
   | PS384 | http://www.w3.org/2007/05/xm | SHA384withR | 1.2.840.1135 |
   |       | ldsig-more#sha384-rsa-MGF1   | SAandMGF1   | 49.1.1.10    |
   | PS512 | http://www.w3.org/2007/05/xm | SHA512withR | 1.2.840.1135 |
   |       | ldsig-more#sha512-rsa-MGF1   | SAandMGF1   | 49.1.1.10    |
   +-------+------------------------------+-------------+--------------+

A.2.  Key Management Algorithm Identifier Cross-Reference

   This section contains a table cross-referencing the JWE "alg"
   (algorithm) values defined in this specification with the equivalent
   identifiers used by other standards and software packages.










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   +----------+----------------------+-------------------+-------------+
   | JWE      | XML ENC              | JCA               | OID         |
   +----------+----------------------+-------------------+-------------+
   | RSA1_5   | http://www.w3.org/20 | RSA/ECB/PKCS1Padd | 1.2.840.113 |
   |          | 01/04/xmlenc#rsa-1_5 | ing               | 549.1.1.1   |
   | RSA-OAEP | http://www.w3.org/20 | RSA/ECB/OAEPWithS | 1.2.840.113 |
   |          | 01/04/xmlenc#rsa-oae | HA-1AndMGF1Paddin | 549.1.1.7   |
   |          | p-mgf1p              | g                 |             |
   | RSA-OAEP | http://www.w3.org/20 | RSA/ECB/OAEPWithS | 1.2.840.113 |
   | -256     | 09/xmlenc11#rsa-oaep | HA-256AndMGF1Padd | 549.1.1.7   |
   |          |  &                   | ing &             |             |
   |          |  http://www.w3.org/2 |   MGF1ParameterSp |             |
   |          | 009/xmlenc11#mgf1sha | ec.SHA256         |             |
   |          | 256                  |                   |             |
   | ECDH-ES  | http://www.w3.org/20 | ECDH              | 1.3.132.1.1 |
   |          | 09/xmlenc11#ECDH-ES  |                   | 2           |
   | A128KW   | http://www.w3.org/20 | AESWrap           | 2.16.840.1. |
   |          | 01/04/xmlenc#kw-aes1 |                   | 101.3.4.1.5 |
   |          | 28                   |                   |             |
   | A192KW   | http://www.w3.org/20 | AESWrap           | 2.16.840.1. |
   |          | 01/04/xmlenc#kw-aes1 |                   | 101.3.4.1.2 |
   |          | 92                   |                   | 5           |
   | A256KW   | http://www.w3.org/20 | AESWrap           | 2.16.840.1. |
   |          | 01/04/xmlenc#kw-aes2 |                   | 101.3.4.1.4 |
   |          | 56                   |                   | 5           |
   +----------+----------------------+-------------------+-------------+

A.3.  Content Encryption Algorithm Identifier Cross-Reference

   This section contains a table cross-referencing the JWE "enc"
   (encryption algorithm) values defined in this specification with the
   equivalent identifiers used by other standards and software packages.

   For the composite algorithms "A128CBC-HS256", "A192CBC-HS384", and
   "A256CBC-HS512", the corresponding AES CBC algorithm identifiers are
   listed.

   +----------+-------------------------+--------------+---------------+
   | JWE      | XML ENC                 | JCA          | OID           |
   +----------+-------------------------+--------------+---------------+
   | A128CBC- | http://www.w3.org/2001/ | AES/CBC/PKCS | 2.16.840.1.10 |
   | HS256    | 04/xmlenc#aes128-cbc    | 5Padding     | 1.3.4.1.2     |
   | A192CBC- | http://www.w3.org/2001/ | AES/CBC/PKCS | 2.16.840.1.10 |
   | HS384    | 04/xmlenc#aes192-cbc    | 5Padding     | 1.3.4.1.22    |
   | A256CBC- | http://www.w3.org/2001/ | AES/CBC/PKCS | 2.16.840.1.10 |
   | HS512    | 04/xmlenc#aes256-cbc    | 5Padding     | 1.3.4.1.42    |
   | A128GCM  | http://www.w3.org/2009/ | AES/GCM/NoPa | 2.16.840.1.10 |
   |          | xmlenc11#aes128-gcm     | dding        | 1.3.4.1.6     |



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   | A192GCM  | http://www.w3.org/2009/ | AES/GCM/NoPa | 2.16.840.1.10 |
   |          | xmlenc11#aes192-gcm     | dding        | 1.3.4.1.26    |
   | A256GCM  | http://www.w3.org/2009/ | AES/GCM/NoPa | 2.16.840.1.10 |
   |          | xmlenc11#aes256-gcm     | dding        | 1.3.4.1.46    |
   +----------+-------------------------+--------------+---------------+


Appendix B.  Test Cases for AES_CBC_HMAC_SHA2 Algorithms

   The following test cases can be used to validate implementations of
   the AES_CBC_HMAC_SHA2 algorithms defined in Section 5.2.  They are
   also intended to correspond to test cases that may appear in a future
   version of [I-D.mcgrew-aead-aes-cbc-hmac-sha2], demonstrating that
   the cryptographic computations performed are the same.

   The variable names are those defined in Section 5.2.  All values are
   hexadecimal.


































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B.1.  Test Cases for AES_128_CBC_HMAC_SHA_256

   AES_128_CBC_HMAC_SHA_256

     K =       00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f

     MAC_KEY = 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f

     ENC_KEY = 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f

     P =       41 20 63 69 70 68 65 72 20 73 79 73 74 65 6d 20
               6d 75 73 74 20 6e 6f 74 20 62 65 20 72 65 71 75
               69 72 65 64 20 74 6f 20 62 65 20 73 65 63 72 65
               74 2c 20 61 6e 64 20 69 74 20 6d 75 73 74 20 62
               65 20 61 62 6c 65 20 74 6f 20 66 61 6c 6c 20 69
               6e 74 6f 20 74 68 65 20 68 61 6e 64 73 20 6f 66
               20 74 68 65 20 65 6e 65 6d 79 20 77 69 74 68 6f
               75 74 20 69 6e 63 6f 6e 76 65 6e 69 65 6e 63 65

     IV =      1a f3 8c 2d c2 b9 6f fd d8 66 94 09 23 41 bc 04

     A =       54 68 65 20 73 65 63 6f 6e 64 20 70 72 69 6e 63
               69 70 6c 65 20 6f 66 20 41 75 67 75 73 74 65 20
               4b 65 72 63 6b 68 6f 66 66 73

     AL =      00 00 00 00 00 00 01 50

     E =       c8 0e df a3 2d df 39 d5 ef 00 c0 b4 68 83 42 79
               a2 e4 6a 1b 80 49 f7 92 f7 6b fe 54 b9 03 a9 c9
               a9 4a c9 b4 7a d2 65 5c 5f 10 f9 ae f7 14 27 e2
               fc 6f 9b 3f 39 9a 22 14 89 f1 63 62 c7 03 23 36
               09 d4 5a c6 98 64 e3 32 1c f8 29 35 ac 40 96 c8
               6e 13 33 14 c5 40 19 e8 ca 79 80 df a4 b9 cf 1b
               38 4c 48 6f 3a 54 c5 10 78 15 8e e5 d7 9d e5 9f
               bd 34 d8 48 b3 d6 95 50 a6 76 46 34 44 27 ad e5
               4b 88 51 ff b5 98 f7 f8 00 74 b9 47 3c 82 e2 db

     M =       65 2c 3f a3 6b 0a 7c 5b 32 19 fa b3 a3 0b c1 c4
               e6 e5 45 82 47 65 15 f0 ad 9f 75 a2 b7 1c 73 ef

     T =       65 2c 3f a3 6b 0a 7c 5b 32 19 fa b3 a3 0b c1 c4









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B.2.  Test Cases for AES_192_CBC_HMAC_SHA_384

     K =       00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
               20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f

     MAC_KEY = 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
               10 11 12 13 14 15 16 17

     ENC_KEY = 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27
               28 29 2a 2b 2c 2d 2e 2f

     P =       41 20 63 69 70 68 65 72 20 73 79 73 74 65 6d 20
               6d 75 73 74 20 6e 6f 74 20 62 65 20 72 65 71 75
               69 72 65 64 20 74 6f 20 62 65 20 73 65 63 72 65
               74 2c 20 61 6e 64 20 69 74 20 6d 75 73 74 20 62
               65 20 61 62 6c 65 20 74 6f 20 66 61 6c 6c 20 69
               6e 74 6f 20 74 68 65 20 68 61 6e 64 73 20 6f 66
               20 74 68 65 20 65 6e 65 6d 79 20 77 69 74 68 6f
               75 74 20 69 6e 63 6f 6e 76 65 6e 69 65 6e 63 65

     IV =      1a f3 8c 2d c2 b9 6f fd d8 66 94 09 23 41 bc 04

     A =       54 68 65 20 73 65 63 6f 6e 64 20 70 72 69 6e 63
               69 70 6c 65 20 6f 66 20 41 75 67 75 73 74 65 20
               4b 65 72 63 6b 68 6f 66 66 73

     AL =      00 00 00 00 00 00 01 50

     E =       ea 65 da 6b 59 e6 1e db 41 9b e6 2d 19 71 2a e5
               d3 03 ee b5 00 52 d0 df d6 69 7f 77 22 4c 8e db
               00 0d 27 9b dc 14 c1 07 26 54 bd 30 94 42 30 c6
               57 be d4 ca 0c 9f 4a 84 66 f2 2b 22 6d 17 46 21
               4b f8 cf c2 40 0a dd 9f 51 26 e4 79 66 3f c9 0b
               3b ed 78 7a 2f 0f fc bf 39 04 be 2a 64 1d 5c 21
               05 bf e5 91 ba e2 3b 1d 74 49 e5 32 ee f6 0a 9a
               c8 bb 6c 6b 01 d3 5d 49 78 7b cd 57 ef 48 49 27
               f2 80 ad c9 1a c0 c4 e7 9c 7b 11 ef c6 00 54 e3

     M =       84 90 ac 0e 58 94 9b fe 51 87 5d 73 3f 93 ac 20
               75 16 80 39 cc c7 33 d7 45 94 f8 86 b3 fa af d4
               86 f2 5c 71 31 e3 28 1e 36 c7 a2 d1 30 af de 57

     T =       84 90 ac 0e 58 94 9b fe 51 87 5d 73 3f 93 ac 20
               75 16 80 39 cc c7 33 d7






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B.3.  Test Cases for AES_256_CBC_HMAC_SHA_512

     K =       00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
               20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
               30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f

     MAC_KEY = 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
               10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f

     ENC_KEY = 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
               30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f

     P =       41 20 63 69 70 68 65 72 20 73 79 73 74 65 6d 20
               6d 75 73 74 20 6e 6f 74 20 62 65 20 72 65 71 75
               69 72 65 64 20 74 6f 20 62 65 20 73 65 63 72 65
               74 2c 20 61 6e 64 20 69 74 20 6d 75 73 74 20 62
               65 20 61 62 6c 65 20 74 6f 20 66 61 6c 6c 20 69
               6e 74 6f 20 74 68 65 20 68 61 6e 64 73 20 6f 66
               20 74 68 65 20 65 6e 65 6d 79 20 77 69 74 68 6f
               75 74 20 69 6e 63 6f 6e 76 65 6e 69 65 6e 63 65

     IV =      1a f3 8c 2d c2 b9 6f fd d8 66 94 09 23 41 bc 04

     A =       54 68 65 20 73 65 63 6f 6e 64 20 70 72 69 6e 63
               69 70 6c 65 20 6f 66 20 41 75 67 75 73 74 65 20
               4b 65 72 63 6b 68 6f 66 66 73

     AL =      00 00 00 00 00 00 01 50

     E =       4a ff aa ad b7 8c 31 c5 da 4b 1b 59 0d 10 ff bd
               3d d8 d5 d3 02 42 35 26 91 2d a0 37 ec bc c7 bd
               82 2c 30 1d d6 7c 37 3b cc b5 84 ad 3e 92 79 c2
               e6 d1 2a 13 74 b7 7f 07 75 53 df 82 94 10 44 6b
               36 eb d9 70 66 29 6a e6 42 7e a7 5c 2e 08 46 a1
               1a 09 cc f5 37 0d c8 0b fe cb ad 28 c7 3f 09 b3
               a3 b7 5e 66 2a 25 94 41 0a e4 96 b2 e2 e6 60 9e
               31 e6 e0 2c c8 37 f0 53 d2 1f 37 ff 4f 51 95 0b
               be 26 38 d0 9d d7 a4 93 09 30 80 6d 07 03 b1 f6

     M =       4d d3 b4 c0 88 a7 f4 5c 21 68 39 64 5b 20 12 bf
               2e 62 69 a8 c5 6a 81 6d bc 1b 26 77 61 95 5b c5
               fd 30 a5 65 c6 16 ff b2 f3 64 ba ec e6 8f c4 07
               53 bc fc 02 5d de 36 93 75 4a a1 f5 c3 37 3b 9c

     T =       4d d3 b4 c0 88 a7 f4 5c 21 68 39 64 5b 20 12 bf
               2e 62 69 a8 c5 6a 81 6d bc 1b 26 77 61 95 5b c5




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Appendix C.  Example ECDH-ES Key Agreement Computation

   This example uses ECDH-ES Key Agreement and the Concat KDF to derive
   the Content Encryption Key (CEK) in the manner described in
   Section 4.6.  In this example, the ECDH-ES Direct Key Agreement mode
   ("alg" value "ECDH-ES") is used to produce an agreed upon key for AES
   GCM with a 128 bit key ("enc" value "A128GCM").

   In this example, a producer Alice is encrypting content to a consumer
   Bob. The producer (Alice) generates an ephemeral key for the key
   agreement computation.  Alice's ephemeral key (in JWK format) used
   for the key agreement computation in this example (including the
   private part) is:

     {"kty":"EC",
      "crv":"P-256",
      "x":"gI0GAILBdu7T53akrFmMyGcsF3n5dO7MmwNBHKW5SV0",
      "y":"SLW_xSffzlPWrHEVI30DHM_4egVwt3NQqeUD7nMFpps",
      "d":"0_NxaRPUMQoAJt50Gz8YiTr8gRTwyEaCumd-MToTmIo"
     }

   The consumer's (Bob's) key (in JWK format) used for the key agreement
   computation in this example (including the private part) is:

     {"kty":"EC",
      "crv":"P-256",
      "x":"weNJy2HscCSM6AEDTDg04biOvhFhyyWvOHQfeF_PxMQ",
      "y":"e8lnCO-AlStT-NJVX-crhB7QRYhiix03illJOVAOyck",
      "d":"VEmDZpDXXK8p8N0Cndsxs924q6nS1RXFASRl6BfUqdw"
     }

   Header Parameter values used in this example are as follows.  In this
   example, the "apu" (agreement PartyUInfo) parameter value is the
   base64url encoding of the UTF-8 string "Alice" and the "apv"
   (agreement PartyVInfo) parameter value is the base64url encoding of
   the UTF-8 string "Bob".  The "epk" parameter is used to communicate
   the producer's (Alice's) ephemeral public key value to the consumer
   (Bob).













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     {"alg":"ECDH-ES",
      "enc":"A128GCM",
      "apu":"QWxpY2U",
      "apv":"Qm9i",
      "epk":
       {"kty":"EC",
        "crv":"P-256",
        "x":"gI0GAILBdu7T53akrFmMyGcsF3n5dO7MmwNBHKW5SV0",
        "y":"SLW_xSffzlPWrHEVI30DHM_4egVwt3NQqeUD7nMFpps"
       }
     }

   The resulting Concat KDF [NIST.800-56A] parameter values are:

   Z
      This is set to the ECDH-ES key agreement output.  (This value is
      often not directly exposed by libraries, due to NIST security
      requirements, and only serves as an input to a KDF.)  In this
      example, Z is following the octet sequence (using JSON array
      notation):
      [158, 86, 217, 29, 129, 113, 53, 211, 114, 131, 66, 131, 191, 132,
      38, 156, 251, 49, 110, 163, 218, 128, 106, 72, 246, 218, 167, 121,
      140, 254, 144, 196].

   keydatalen
      This value is 128 - the number of bits in the desired output key
      (because "A128GCM" uses a 128 bit key).

   AlgorithmID
      This is set to the octets representing the 32 bit big endian value
      7 - [0, 0, 0, 7] - the number of octets in the AlgorithmID content
      "A128GCM", followed, by the octets representing the ASCII string
      "A128GCM" - [65, 49, 50, 56, 71, 67, 77].

   PartyUInfo
      This is set to the octets representing the 32 bit big endian value
      5 - [0, 0, 0, 5] - the number of octets in the PartyUInfo content
      "Alice", followed, by the octets representing the UTF-8 string
      "Alice" - [65, 108, 105, 99, 101].

   PartyVInfo
      This is set to the octets representing the 32 bit big endian value
      3 - [0, 0, 0, 3] - the number of octets in the PartyUInfo content
      "Bob", followed, by the octets representing the UTF-8 string "Bob"
      - [66, 111, 98].






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   SuppPubInfo
      This is set to the octets representing the 32 bit big endian value
      128 - [0, 0, 0, 128] - the keydatalen value.

   SuppPrivInfo
      This is set to the empty octet sequence.

   Concatenating the parameters AlgorithmID through SuppPubInfo results
   in an OtherInfo value of:
   [0, 0, 0, 7, 65, 49, 50, 56, 71, 67, 77, 0, 0, 0, 5, 65, 108, 105,
   99, 101, 0, 0, 0, 3, 66, 111, 98, 0, 0, 0, 128]

   Concatenating the round number 1 ([0, 0, 0, 1]), Z, and the OtherInfo
   value results in the Concat KDF round 1 hash input of:
   [0, 0, 0, 1,
   158, 86, 217, 29, 129, 113, 53, 211, 114, 131, 66, 131, 191, 132, 38,
   156, 251, 49, 110, 163, 218, 128, 106, 72, 246, 218, 167, 121, 140,
   254, 144, 196,
   0, 0, 0, 7, 65, 49, 50, 56, 71, 67, 77, 0, 0, 0, 5, 65, 108, 105, 99,
   101, 0, 0, 0, 3, 66, 111, 98, 0, 0, 0, 128]

   The resulting derived key, which is the first 128 bits of the round 1
   hash output is:
   [86, 170, 141, 234, 248, 35, 109, 32, 92, 34, 40, 205, 113, 167, 16,
   26]

   The base64url encoded representation of this derived key is:

     VqqN6vgjbSBcIijNcacQGg


Appendix D.  Acknowledgements

   Solutions for signing and encrypting JSON content were previously
   explored by Magic Signatures [MagicSignatures], JSON Simple Sign
   [JSS], Canvas Applications [CanvasApp], JSON Simple Encryption [JSE],
   and JavaScript Message Security Format [I-D.rescorla-jsms], all of
   which influenced this draft.

   The Authenticated Encryption with AES-CBC and HMAC-SHA
   [I-D.mcgrew-aead-aes-cbc-hmac-sha2] specification, upon which the
   AES_CBC_HMAC_SHA2 algorithms are based, was written by David A.
   McGrew and Kenny Paterson.  The test cases for AES_CBC_HMAC_SHA2 are
   based upon those for [I-D.mcgrew-aead-aes-cbc-hmac-sha2] by John
   Foley.

   Matt Miller wrote Using JavaScript Object Notation (JSON) Web
   Encryption (JWE) for Protecting JSON Web Key (JWK) Objects



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   [I-D.miller-jose-jwe-protected-jwk], which the password-based
   encryption content of this draft is based upon.

   This specification is the work of the JOSE Working Group, which
   includes dozens of active and dedicated participants.  In particular,
   the following individuals contributed ideas, feedback, and wording
   that influenced this specification:

   Dirk Balfanz, Richard Barnes, Carsten Bormann, John Bradley, Brian
   Campbell, Alissa Cooper, Breno de Medeiros, Vladimir Dzhuvinov, Roni
   Even, Stephen Farrell, Yaron Y. Goland, Dick Hardt, Joe Hildebrand,
   Jeff Hodges, Edmund Jay, Charlie Kaufman, Barry Leiba, James Manger,
   Matt Miller, Kathleen Moriarty, Tony Nadalin, Axel Nennker, John
   Panzer, Emmanuel Raviart, Eric Rescorla, Pete Resnick, Nat Sakimura,
   Jim Schaad, Hannes Tschofenig, and Sean Turner.

   Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
   Sean Turner, Stephen Farrell, and Kathleen Moriarty served as
   Security area directors during the creation of this specification.


Appendix E.  Document History

   [[ to be removed by the RFC Editor before publication as an RFC ]]

   -40

   o  Clarified the definitions of UTF8(STRING) and ASCII(STRING).

   -39

   o  Added the Algorithm Analysis Documents(s) field to the IANA JSON
      Web Signature and Encryption Algorithms registry.

   o  Updated the reference to draft-ietf-precis-saslprepbis.

   -38

   o  Require discarding private keys with an "oth" parameter when the
      implementation does not support private keys with more than two
      primes.

   o  Replaced uses of the phrases "JWS object" and "JWE object" with
      "JWS" and "JWE".

   -37





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   o  Restricted algorithm names to using only ASCII characters.

   o  Added language about ignoring private keys with an "oth" parameter
      when the implementation does not support private keys with more
      than two primes.

   o  Updated the example IANA registration request subject line.

   -36

   o  Moved the normative "alg":"none" security considerations text into
      the algorithm definition.

   o  Specified that registration reviews occur on the
      jose-reg-review@ietf.org mailing list.

   -35

   o  Addressed AppsDir reviews by Carsten Bormann.

   o  Adjusted some table column widths.

   -34

   o  Addressed IESG review comments by Barry Leiba, Alissa Cooper, Pete
      Resnick, Stephen Farrell, and Richard Barnes.

   -33

   o  Changed the registration review period to three weeks.

   o  Acknowledged additional contributors.

   -32

   o  Added a note to implementers about libraries that prefix an extra
      zero-valued octet to RSA modulus representations returned.

   o  Addressed secdir review comments by Charlie Kaufman, Scott Kelly,
      and Stephen Kent.

   o  Addressed Gen-ART review comments by Roni Even.

   o  Replaced the term Plaintext JWS with Unsecured JWS.

   -31





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   o  Referenced NIST SP 800-57 for guidance on key lifetimes.

   o  Updated the reference to draft-mcgrew-aead-aes-cbc-hmac-sha2.

   -30

   o  Cleaned up the reference syntax in a few places.

   o  Applied minor wording changes to the Security Considerations
      section.

   -29

   o  Replaced the terms JWS Header, JWE Header, and JWT Header with a
      single JOSE Header term defined in the JWS specification.  This
      also enabled a single Header Parameter definition to be used and
      reduced other areas of duplication between specifications.

   -28

   o  Specified the use of PKCS #7 padding with AES CBC, rather than
      PKCS #5.  (PKCS #7 is a superset of PKCS #5, and is appropriate
      for the 16 octet blocks used by AES CBC.)

   o  Revised the introduction to the Security Considerations section.
      Also introduced additional subsection headings for security
      considerations items and moved a few security consideration items
      from here to the JWS and JWE drafts.

   -27

   o  Described additional security considerations.

   o  Updated the JCA and XMLENC parameters for "RSA-OAEP-256" and the
      JCA parameters for "A128KW", "A192KW", "A256KW", and "ECDH-ES".

   -26

   o  Added algorithm identifier "RSA-OAEP-256" for RSAES OAEP using
      SHA-256 and MGF1 with SHA-256.

   o  Clarified that the ECDSA signature values R and S are represented
      as octet sequences as defined in Section 2.3.7 of SEC1 [SEC1].

   o  Noted that octet sequences are depicted using JSON array notation.

   o  Updated references, including to W3C specifications.




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   -25

   o  Corrected an external section number reference that had changed.

   -24

   o  Replaced uses of the term "associated data" wherever it was used
      to refer to a data value with "additional authenticated data",
      since both terms were being used as synonyms, causing confusion.

   o  Updated the JSON reference to RFC 7159.

   -23

   o  No changes were made, other than to the version number and date.

   -22

   o  Corrected RFC 2119 terminology usage.

   o  Replaced references to draft-ietf-json-rfc4627bis with RFC 7158.

   -21

   o  Compute the PBES2 salt parameter as (UTF8(Alg) || 0x00 || Salt
      Input), where the "p2s" Header Parameter encodes the Salt Input
      value and Alg is the "alg" Header Parameter value.

   o  Changed some references from being normative to informative,
      addressing issue #90.

   -20

   o  Replaced references to RFC 4627 with draft-ietf-json-rfc4627bis,
      addressing issue #90.

   -19

   o  Used tables to show the correspondence between algorithm
      identifiers and algorithm descriptions and parameters in the
      algorithm definition sections, addressing issue #183.

   o  Changed the "Implementation Requirements" registry field names to
      "JOSE Implementation Requirements" to make it clear that these
      implementation requirements apply only to JWS and JWE
      implementations.

   -18



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   o  Changes to address editorial and minor issues #129, #134, #135,
      #158, #161, #185, #186, and #187.

   o  Added and used Description registry fields.

   -17

   o  Explicitly named all the logical components of a JWS and JWE and
      defined the processing rules and serializations in terms of those
      components, addressing issues #60, #61, and #62.

   o  Removed processing steps in algorithm definitions that duplicated
      processing steps in JWS or JWE, addressing issue #56.

   o  Replaced verbose repetitive phases such as "base64url encode the
      octets of the UTF-8 representation of X" with mathematical
      notation such as "BASE64URL(UTF8(X))".

   o  Terms used in multiple documents are now defined in one place and
      incorporated by reference.  Some lightly used or obvious terms
      were also removed.  This addresses issue #58.

   o  Changes to address minor issue #53.

   -16

   o  Added a DataLen prefix to the AlgorithmID value in the Concat KDF
      computation.

   o  Added OIDs for encryption algorithms, additional signature
      algorithm OIDs, and additional XML DSIG/ENC URIs in the algorithm
      cross-reference tables.

   o  Changes to address editorial and minor issues #28, #36, #39, #52,
      #53, #55, #127, #128, #136, #137, #141, #150, #151, #152, and
      #155.

   -15

   o  Changed statements about rejecting JWSs to statements about
      validation failing, addressing issue #35.

   o  Stated that changes of implementation requirements are only
      permitted on a Specification Required basis, addressing issue #38.

   o  Made "oct" a required key type, addressing issue #40.





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   o  Updated the example ECDH-ES key agreement values.

   o  Changes to address editorial and minor issues #34, #37, #49, #63,
      #123, #124, #125, #130, #132, #133, #138, #139, #140, #142, #143,
      #144, #145, #148, #149, #150, and #162.

   -14

   o  Removed "PBKDF2" key type and added "p2s" and "p2c" header
      parameters for use with the PBES2 algorithms.

   o  Made the RSA private key parameters that are there to enable
      optimizations be RECOMMENDED rather than REQUIRED.

   o  Added algorithm identifiers for AES algorithms using 192 bit keys
      and for RSASSA-PSS using HMAC SHA-384.

   o  Added security considerations about key lifetimes, addressing
      issue #18.

   o  Added an example ECDH-ES key agreement computation.

   -13

   o  Added key encryption with AES GCM as specified in
      draft-jones-jose-aes-gcm-key-wrap-01, addressing issue #13.

   o  Added security considerations text limiting the number of times
      that an AES GCM key can be used for key encryption or direct
      encryption, per Section 8.3 of NIST SP 800-38D, addressing issue
      #28.

   o  Added password-based key encryption as specified in
      draft-miller-jose-jwe-protected-jwk-02.

   -12

   o  In the Direct Key Agreement case, the Concat KDF AlgorithmID is
      set to the octets of the UTF-8 representation of the "enc" header
      parameter value.

   o  Restored the "apv" (agreement PartyVInfo) parameter.

   o  Moved the "epk", "apu", and "apv" Header Parameter definitions to
      be with the algorithm descriptions that use them.

   o  Changed terminology from "block encryption" to "content
      encryption".



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   -11

   o  Removed the Encrypted Key value from the AAD computation since it
      is already effectively integrity protected by the encryption
      process.  The AAD value now only contains the representation of
      the JWE Encrypted Header.

   o  Removed "apv" (agreement PartyVInfo) since it is no longer used.

   o  Added more information about the use of PartyUInfo during key
      agreement.

   o  Use the keydatalen as the SuppPubInfo value for the Concat KDF
      when doing key agreement, as RFC 2631 does.

   o  Added algorithm identifiers for RSASSA-PSS with SHA-256 and SHA-
      512.

   o  Added a Parameter Information Class value to the JSON Web Key
      Parameters registry, which registers whether the parameter conveys
      public or private information.

   -10

   o  Changed the JWE processing rules for multiple recipients so that a
      single AAD value contains the header parameters and encrypted key
      values for all the recipients, enabling AES GCM to be safely used
      for multiple recipients.

   -09

   o  Expanded the scope of the JWK parameters to include private and
      symmetric key representations, as specified by
      draft-jones-jose-json-private-and-symmetric-key-00.

   o  Changed term "JWS Secured Input" to "JWS Signing Input".

   o  Changed from using the term "byte" to "octet" when referring to 8
      bit values.

   o  Specified that AES Key Wrap uses the default initial value
      specified in Section 2.2.3.1 of RFC 3394.  This addressed issue
      #19.

   o  Added Key Management Mode definitions to terminology section and
      used the defined terms to provide clearer key management
      instructions.  This addressed issue #5.




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   o  Replaced "A128CBC+HS256" and "A256CBC+HS512" with "A128CBC-HS256"
      and "A256CBC-HS512".  The new algorithms perform the same
      cryptographic computations as [I-D.mcgrew-aead-aes-cbc-hmac-sha2],
      but with the Initialization Vector and Authentication Tag values
      remaining separate from the Ciphertext value in the output
      representation.  Also deleted the header parameters "epu"
      (encryption PartyUInfo) and "epv" (encryption PartyVInfo), since
      they are no longer used.

   o  Changed from using the term "Integrity Value" to "Authentication
      Tag".

   -08

   o  Changed the name of the JWK key type parameter from "alg" to
      "kty".

   o  Replaced uses of the term "AEAD" with "Authenticated Encryption",
      since the term AEAD in the RFC 5116 sense implied the use of a
      particular data representation, rather than just referring to the
      class of algorithms that perform authenticated encryption with
      associated data.

   o  Applied editorial improvements suggested by Jeff Hodges.  Many of
      these simplified the terminology used.

   o  Added seriesInfo information to Internet Draft references.

   -07

   o  Added a data length prefix to PartyUInfo and PartyVInfo values.

   o  Changed the name of the JWK RSA modulus parameter from "mod" to
      "n" and the name of the JWK RSA exponent parameter from "xpo" to
      "e", so that the identifiers are the same as those used in RFC
      3447.

   o  Made several local editorial changes to clean up loose ends left
      over from to the decision to only support block encryption methods
      providing integrity.

   -06

   o  Removed the "int" and "kdf" parameters and defined the new
      composite Authenticated Encryption algorithms "A128CBC+HS256" and
      "A256CBC+HS512" to replace the former uses of AES CBC, which
      required the use of separate integrity and key derivation
      functions.



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   o  Included additional values in the Concat KDF calculation -- the
      desired output size and the algorithm value, and optionally
      PartyUInfo and PartyVInfo values.  Added the optional header
      parameters "apu" (agreement PartyUInfo), "apv" (agreement
      PartyVInfo), "epu" (encryption PartyUInfo), and "epv" (encryption
      PartyVInfo).

   o  Changed the name of the JWK RSA exponent parameter from "exp" to
      "xpo" so as to allow the potential use of the name "exp" for a
      future extension that might define an expiration parameter for
      keys.  (The "exp" name is already used for this purpose in the JWT
      specification.)

   o  Applied changes made by the RFC Editor to RFC 6749's registry
      language to this specification.

   -05

   o  Support both direct encryption using a shared or agreed upon
      symmetric key, and the use of a shared or agreed upon symmetric
      key to key wrap the CMK.  Specifically, added the "alg" values
      "dir", "ECDH-ES+A128KW", and "ECDH-ES+A256KW" to finish filling in
      this set of capabilities.

   o  Updated open issues.

   -04

   o  Added text requiring that any leading zero bytes be retained in
      base64url encoded key value representations for fixed-length
      values.

   o  Added this language to Registration Templates: "This name is case
      sensitive.  Names that match other registered names in a case
      insensitive manner SHOULD NOT be accepted."

   o  Described additional open issues.

   o  Applied editorial suggestions.

   -03

   o  Always use a 128 bit "authentication tag" size for AES GCM,
      regardless of the key size.

   o  Specified that use of a 128 bit IV is REQUIRED with AES CBC.  It
      was previously RECOMMENDED.




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   o  Removed key size language for ECDSA algorithms, since the key size
      is implied by the algorithm being used.

   o  Stated that the "int" key size must be the same as the hash output
      size (and not larger, as was previously allowed) so that its size
      is defined for key generation purposes.

   o  Added the "kdf" (key derivation function) header parameter to
      provide crypto agility for key derivation.  The default KDF
      remains the Concat KDF with the SHA-256 digest function.

   o  Clarified that the "mod" and "exp" values are unsigned.

   o  Added Implementation Requirements columns to algorithm tables and
      Implementation Requirements entries to algorithm registries.

   o  Changed AES Key Wrap to RECOMMENDED.

   o  Moved registries JSON Web Signature and Encryption Header
      Parameters and JSON Web Signature and Encryption Type Values to
      the JWS specification.

   o  Moved JSON Web Key Parameters registry to the JWK specification.

   o  Changed registration requirements from RFC Required to
      Specification Required with Expert Review.

   o  Added Registration Template sections for defined registries.

   o  Added Registry Contents sections to populate registry values.

   o  No longer say "the UTF-8 representation of the JWS Secured Input
      (which is the same as the ASCII representation)".  Just call it
      "the ASCII representation of the JWS Secured Input".

   o  Added "Collision Resistant Namespace" to the terminology section.

   o  Numerous editorial improvements.

   -02

   o  For AES GCM, use the "additional authenticated data" parameter to
      provide integrity for the header, encrypted key, and ciphertext
      and use the resulting "authentication tag" value as the JWE
      Authentication Tag.

   o  Defined minimum required key sizes for algorithms without
      specified key sizes.



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   o  Defined KDF output key sizes.

   o  Specified the use of PKCS #5 padding with AES CBC.

   o  Generalized text to allow key agreement to be employed as an
      alternative to key wrapping or key encryption.

   o  Clarified that ECDH-ES is a key agreement algorithm.

   o  Required implementation of AES-128-KW and AES-256-KW.

   o  Removed the use of "A128GCM" and "A256GCM" for key wrapping.

   o  Removed "A512KW" since it turns out that it's not a standard
      algorithm.

   o  Clarified the relationship between "typ" header parameter values
      and MIME types.

   o  Generalized language to refer to Message Authentication Codes
      (MACs) rather than Hash-based Message Authentication Codes (HMACs)
      unless in a context specific to HMAC algorithms.

   o  Established registries: JSON Web Signature and Encryption Header
      Parameters, JSON Web Signature and Encryption Algorithms, JSON Web
      Signature and Encryption "typ" Values, JSON Web Key Parameters,
      and JSON Web Key Algorithm Families.

   o  Moved algorithm-specific definitions from JWK to JWA.

   o  Reformatted to give each member definition its own section
      heading.

   -01

   o  Moved definition of "alg":"none" for JWSs here from the JWT
      specification since this functionality is likely to be useful in
      more contexts that just for JWTs.

   o  Added Advanced Encryption Standard (AES) Key Wrap Algorithm using
      512 bit keys ("A512KW").

   o  Added text "Alternatively, the Encoded JWS Signature MAY be
      base64url decoded to produce the JWS Signature and this value can
      be compared with the computed HMAC value, as this comparison
      produces the same result as comparing the encoded values".





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   o  Corrected the Magic Signatures reference.

   o  Made other editorial improvements suggested by JOSE working group
      participants.

   -00

   o  Created the initial IETF draft based upon
      draft-jones-json-web-signature-04 and
      draft-jones-json-web-encryption-02 with no normative changes.

   o  Changed terminology to no longer call both digital signatures and
      HMACs "signatures".


Author's Address

   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com
   URI:   http://self-issued.info/





























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