Botan: src/rng/x931_rng/x931_rng.cpp Source File

Botan 1.10.17

x931_rng.cpp
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1 /*
2 * ANSI X9.31 RNG
3 * (C) 1999-2009 Jack Lloyd
4 *
5 * Distributed under the terms of the Botan license
6 */
7
8 #include <botan/x931_rng.h>
9 #include <botan/internal/xor_buf.h>
10 #include <algorithm>
11
12 namespace Botan {
13
14 /*
15 * Generate a buffer of random bytes
16 */
17 void ANSI_X931_RNG::randomize(byte out[], size_t length)
18 {
19 if(!is_seeded())
20 throw PRNG_Unseeded(name());
21
22 while(length)
23 {
24 if(position == R.size())
25 update_buffer();
26
27 const size_t copied = std::min<size_t>(length, R.size() - position);
28
29 copy_mem(out, &R[position], copied);
30 out += copied;
31 length -= copied;
32 position += copied;
33 }
34 }
35
36 /*
37 * Refill the internal state
38 */
39 void ANSI_X931_RNG::update_buffer()
40 {
41 const size_t BLOCK_SIZE = cipher->block_size();
42
43 SecureVector<byte> DT = prng->random_vec(BLOCK_SIZE);
44 cipher->encrypt(DT);
45
46 xor_buf(&R[0], &V[0], &DT[0], BLOCK_SIZE);
47 cipher->encrypt(R);
48
49 xor_buf(&V[0], &R[0], &DT[0], BLOCK_SIZE);
50 cipher->encrypt(V);
51
52 position = 0;
53 }
54
55 /*
56 * Reset V and the cipher key with new values
57 */
58 void ANSI_X931_RNG::rekey()
59 {
60 const size_t BLOCK_SIZE = cipher->block_size();
61
62 if(prng->is_seeded())
63 {
64 cipher->set_key(prng->random_vec(cipher->maximum_keylength()));
65
66 if(V.size() != BLOCK_SIZE)
67 V.resize(BLOCK_SIZE);
68 prng->randomize(&V[0], V.size());
69
70 update_buffer();
71 }
72 }
73
74 /*
75 * Reseed the internal state
76 */
77 void ANSI_X931_RNG::reseed(size_t poll_bits)
78 {
79 prng->reseed(poll_bits);
80 rekey();
81 }
82
83 /*
84 * Add a entropy source to the underlying PRNG
85 */
86 void ANSI_X931_RNG::add_entropy_source(EntropySource* src)
87 {
88 prng->add_entropy_source(src);
89 }
90
91 /*
92 * Add some entropy to the underlying PRNG
93 */
94 void ANSI_X931_RNG::add_entropy(const byte input[], size_t length)
95 {
96 prng->add_entropy(input, length);
97 rekey();
98 }
99
100 /*
101 * Check if the the PRNG is seeded
102 */
103 bool ANSI_X931_RNG::is_seeded() const
104 {
105 return (V.size() > 0);
106 }
107
108 /*
109 * Clear memory of sensitive data
110 */
111 void ANSI_X931_RNG::clear()
112 {
113 cipher->clear();
114 prng->clear();
115 zeroise(R);
116 V.clear();
117
118 position = 0;
119 }
120
121 /*
122 * Return the name of this type
123 */
124 std::string ANSI_X931_RNG::name() const
125 {
126 return "X9.31(" + cipher->name() + ")";
127 }
128
129 /*
130 * ANSI X931 RNG Constructor
131 */
132 ANSI_X931_RNG::ANSI_X931_RNG(BlockCipher* cipher_in,
133 RandomNumberGenerator* prng_in)
134 {
135 if(!prng_in || !cipher_in)
136 throw Invalid_Argument("ANSI_X931_RNG constructor: NULL arguments");
137
138 cipher = cipher_in;
139 prng = prng_in;
140
141 R.resize(cipher->block_size());
142 position = 0;
143 }
144
145 /*
146 * ANSI X931 RNG Destructor
147 */
148 ANSI_X931_RNG::~ANSI_X931_RNG()
149 {
150 delete cipher;
151 delete prng;
152 }
153
154 }
Botan::MemoryRegion::resize
void resize(size_t n)
Definition: secmem.h:217
Botan::RandomNumberGenerator::randomize
virtual void randomize(byte output[], size_t length)=0
Botan::Algorithm::clear
virtual void clear()=0
Botan::RandomNumberGenerator::add_entropy
virtual void add_entropy(const byte in[], size_t length)=0
Botan::RandomNumberGenerator
Definition: rng.h:20
Botan::RandomNumberGenerator::random_vec
SecureVector< byte > random_vec(size_t bytes)
Definition: rng.h:40
Botan::ANSI_X931_RNG::name
std::string name() const
Definition: x931_rng.cpp:124
Botan::MemoryRegion::clear
void clear()
Definition: secmem.h:158
Botan::ANSI_X931_RNG::add_entropy
void add_entropy(const byte[], size_t)
Definition: x931_rng.cpp:94
Botan::ANSI_X931_RNG::randomize
void randomize(byte[], size_t)
Definition: x931_rng.cpp:17
Botan::RandomNumberGenerator::add_entropy_source
virtual void add_entropy_source(EntropySource *source)=0
Botan::RandomNumberGenerator::reseed
virtual void reseed(size_t bits_to_collect)=0
Botan::ANSI_X931_RNG::clear
void clear()
Definition: x931_rng.cpp:111
Botan::EntropySource
Definition: entropy_src.h:122
Botan::Invalid_Argument
std::invalid_argument Invalid_Argument
Definition: exceptn.h:20
Botan::byte
unsigned char byte
Definition: types.h:22
Botan::SymmetricAlgorithm::maximum_keylength
size_t maximum_keylength() const
Definition: sym_algo.h:33
Botan::ANSI_X931_RNG::ANSI_X931_RNG
ANSI_X931_RNG(BlockCipher *cipher, RandomNumberGenerator *rng)
Definition: x931_rng.cpp:132
Botan::BlockCipher::encrypt
void encrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:47
Botan::SymmetricAlgorithm::set_key
void set_key(const SymmetricKey &key)
Definition: sym_algo.h:60
Botan::ANSI_X931_RNG::reseed
void reseed(size_t poll_bits)
Definition: x931_rng.cpp:77
Botan::ANSI_X931_RNG::is_seeded
bool is_seeded() const
Definition: x931_rng.cpp:103
Botan::copy_mem
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:22
Botan
Definition: algo_base.h:14
Botan::Algorithm::name
virtual std::string name() const =0
Botan::MemoryRegion::size
size_t size() const
Definition: secmem.h:29
Botan::ANSI_X931_RNG::~ANSI_X931_RNG
~ANSI_X931_RNG()
Definition: x931_rng.cpp:148
Botan::RandomNumberGenerator::is_seeded
virtual bool is_seeded() const
Definition: rng.h:57
Botan::SecureVector< byte >
Botan::RandomNumberGenerator::clear
virtual void clear()=0
Botan::ANSI_X931_RNG::add_entropy_source
void add_entropy_source(EntropySource *)
Definition: x931_rng.cpp:86
Botan::xor_buf
void xor_buf(byte out[], const byte in[], size_t length)
Definition: xor_buf.h:21
Botan::zeroise
void zeroise(MemoryRegion< T > &vec)
Definition: secmem.h:428
Botan::BlockCipher::block_size
virtual size_t block_size() const =0
Botan::PRNG_Unseeded
Definition: exceptn.h:89
Botan::BlockCipher
Definition: block_cipher.h:18