@node ocsptool Invocation
@subsection Invoking ocsptool
@pindex ocsptool
@ignore
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#
# DO NOT EDIT THIS FILE   (invoke-ocsptool.texi)
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Ocsptool is a program that can parse and print information about
OCSP requests/responses, generate requests and verify responses.


This section was generated by @strong{AutoGen},
using the @code{agtexi-cmd} template and the option descriptions for the @code{ocsptool} program.
This software is released under the GNU General Public License, version 3 or later.


@anchor{ocsptool usage}
@subsubheading ocsptool help/usage (@option{--help})
@cindex ocsptool help

This is the automatically generated usage text for ocsptool.

The text printed is the same whether selected with the @code{help} option
(@option{--help}) or the @code{more-help} option (@option{--more-help}).  @code{more-help} will print
the usage text by passing it through a pager program.
@code{more-help} is disabled on platforms without a working
@code{fork(2)} function.  The @code{PAGER} environment variable is
used to select the program, defaulting to @file{more}.  Both will exit
with a status code of 0.

@exampleindent 0
@example
ocsptool is unavailable - no --help
@end example
@exampleindent 4

@anchor{ocsptool debug}
@subsubheading debug option (-d)

This is the ``enable debugging'' option.
This option takes a number argument.
Specifies the debug level.
@anchor{ocsptool ask}
@subsubheading ask option

This is the ``ask an ocsp/http server on a certificate validity'' option.
This option takes an optional string argument @file{server name|url}.

@noindent
This option has some usage constraints.  It:
@itemize @bullet
@item
must appear in combination with the following options:
load-cert, load-issuer.
@end itemize

Connects to the specified HTTP OCSP server and queries on the validity of the loaded certificate.
@anchor{ocsptool exit status}
@subsubheading ocsptool exit status

One of the following exit values will be returned:
@table @samp
@item 0 (EXIT_SUCCESS)
Successful program execution.
@item 1 (EXIT_FAILURE)
The operation failed or the command syntax was not valid.
@end table
@anchor{ocsptool See Also}
@subsubheading ocsptool See Also
    certtool (1)
@anchor{ocsptool Examples}
@subsubheading ocsptool Examples
@subsubheading Print information about an OCSP request

To parse an OCSP request and print information about the content, the
@code{-i} or @code{--request-info} parameter may be used as follows.
The @code{-Q} parameter specify the name of the file containing the
OCSP request, and it should contain the OCSP request in binary DER
format.

@example
$ ocsptool -i -Q ocsp-request.der
@end example

The input file may also be sent to standard input like this:

@example
$ cat ocsp-request.der | ocsptool --request-info
@end example

@subsubheading Print information about an OCSP response

Similar to parsing OCSP requests, OCSP responses can be parsed using
the @code{-j} or @code{--response-info} as follows.

@example
$ ocsptool -j -Q ocsp-response.der
$ cat ocsp-response.der | ocsptool --response-info
@end example

@subsubheading Generate an OCSP request

The @code{-q} or @code{--generate-request} parameters are used to
generate an OCSP request.  By default the OCSP request is written to
standard output in binary DER format, but can be stored in a file
using @code{--outfile}.  To generate an OCSP request the issuer of the
certificate to check needs to be specified with @code{--load-issuer}
and the certificate to check with @code{--load-cert}.  By default PEM
format is used for these files, although @code{--inder} can be used to
specify that the input files are in DER format.

@example
$ ocsptool -q --load-issuer issuer.pem --load-cert client.pem \
           --outfile ocsp-request.der
@end example

When generating OCSP requests, the tool will add an OCSP extension
containing a nonce.  This behaviour can be disabled by specifying
@code{--no-nonce}.

@subsubheading Verify signature in OCSP response

To verify the signature in an OCSP response the @code{-e} or
@code{--verify-response} parameter is used.  The tool will read an
OCSP response in DER format from standard input, or from the file
specified by @code{--load-response}.  The OCSP response is verified
against a set of trust anchors, which are specified using
@code{--load-trust}.  The trust anchors are concatenated certificates
in PEM format.  The certificate that signed the OCSP response needs to
be in the set of trust anchors, or the issuer of the signer
certificate needs to be in the set of trust anchors and the OCSP
Extended Key Usage bit has to be asserted in the signer certificate.

@example
$ ocsptool -e --load-trust issuer.pem \
           --load-response ocsp-response.der
@end example

The tool will print status of verification.

@subsubheading Verify signature in OCSP response against given certificate

It is possible to override the normal trust logic if you know that a
certain certificate is supposed to have signed the OCSP response, and
you want to use it to check the signature.  This is achieved using
@code{--load-signer} instead of @code{--load-trust}.  This will load
one certificate and it will be used to verify the signature in the
OCSP response.  It will not check the Extended Key Usage bit.

@example
$ ocsptool -e --load-signer ocsp-signer.pem \
           --load-response ocsp-response.der
@end example

This approach is normally only relevant in two situations.  The first
is when the OCSP response does not contain a copy of the signer
certificate, so the @code{--load-trust} code would fail.  The second
is if you want to avoid the indirect mode where the OCSP response
signer certificate is signed by a trust anchor.

@subsubheading Real-world example

Here is an example of how to generate an OCSP request for a
certificate and to verify the response.  For illustration we'll use
the @code{blog.josefsson.org} host, which (as of writing) uses a
certificate from CACert.  First we'll use @code{gnutls-cli} to get a
copy of the server certificate chain.  The server is not required to
send this information, but this particular one is configured to do so.

@example
$ echo | gnutls-cli -p 443 blog.josefsson.org --print-cert > chain.pem
@end example

Use a text editor on @code{chain.pem} to create three files for each
separate certificates, called @code{cert.pem} for the first
certificate for the domain itself, secondly @code{issuer.pem} for the
intermediate certificate and @code{root.pem} for the final root
certificate.

The domain certificate normally contains a pointer to where the OCSP
responder is located, in the Authority Information Access Information
extension.  For example, from @code{certtool -i < cert.pem} there is
this information:

@example
Authority Information Access Information (not critical):
Access Method: 1.3.6.1.5.5.7.48.1 (id-ad-ocsp)
Access Location URI: http://ocsp.CAcert.org/
@end example

This means the CA support OCSP queries over HTTP.  We are now ready to
create a OCSP request for the certificate.

@example
$ ocsptool --ask ocsp.CAcert.org --load-issuer issuer.pem \
           --load-cert cert.pem --outfile ocsp-response.der
@end example

The request is sent via HTTP to the OCSP server address specified. If the
address is ommited ocsptool will use the address stored in the certificate.
