Botan 2.1.0 Crypto and TLS for C++11

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pssr.cpp
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1 /*
2 * PSSR
3 * (C) 1999-2007 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7
8 #include <botan/pssr.h>
9 #include <botan/mgf1.h>
10 #include <botan/internal/bit_ops.h>
11
12 namespace Botan {
13
14 /*
15 * PSSR Update Operation
16 */
17 void PSSR::update(const uint8_t input[], size_t length)
18 {
19 m_hash->update(input, length);
20 }
21
22 /*
23 * Return the raw (unencoded) data
24 */
25 secure_vector<uint8_t> PSSR::raw_data()
26 {
27 return m_hash->final();
28 }
29
30 /*
31 * PSSR Encode Operation
32 */
33 secure_vector<uint8_t> PSSR::encoding_of(const secure_vector<uint8_t>& msg,
34 size_t output_bits,
35 RandomNumberGenerator& rng)
36 {
37 const size_t HASH_SIZE = m_hash->output_length();
38
39 if(msg.size() != HASH_SIZE)
40 throw Encoding_Error("PSSR::encoding_of: Bad input length");
41 if(output_bits < 8*HASH_SIZE + 8*m_SALT_SIZE + 9)
42 throw Encoding_Error("PSSR::encoding_of: Output length is too small");
43
44 const size_t output_length = (output_bits + 7) / 8;
45
46 secure_vector<uint8_t> salt = rng.random_vec(m_SALT_SIZE);
47
48 for(size_t j = 0; j != 8; ++j)
49 m_hash->update(0);
50 m_hash->update(msg);
51 m_hash->update(salt);
52 secure_vector<uint8_t> H = m_hash->final();
53
54 secure_vector<uint8_t> EM(output_length);
55
56 EM[output_length - HASH_SIZE - m_SALT_SIZE - 2] = 0x01;
57 buffer_insert(EM, output_length - 1 - HASH_SIZE - m_SALT_SIZE, salt);
58 mgf1_mask(*m_hash, H.data(), HASH_SIZE, EM.data(), output_length - HASH_SIZE - 1);
59 EM[0] &= 0xFF >> (8 * ((output_bits + 7) / 8) - output_bits);
60 buffer_insert(EM, output_length - 1 - HASH_SIZE, H);
61 EM[output_length-1] = 0xBC;
62
63 return EM;
64 }
65
66 /*
67 * PSSR Decode/Verify Operation
68 */
69 bool PSSR::verify(const secure_vector<uint8_t>& const_coded,
70 const secure_vector<uint8_t>& raw, size_t key_bits)
71 {
72 const size_t HASH_SIZE = m_hash->output_length();
73 const size_t KEY_BYTES = (key_bits + 7) / 8;
74
75 if(key_bits < 8*HASH_SIZE + 9)
76 return false;
77
78 if(raw.size() != HASH_SIZE)
79 return false;
80
81 if(const_coded.size() > KEY_BYTES || const_coded.size() <= 1)
82 return false;
83
84 if(const_coded[const_coded.size()-1] != 0xBC)
85 return false;
86
87 secure_vector<uint8_t> coded = const_coded;
88 if(coded.size() < KEY_BYTES)
89 {
90 secure_vector<uint8_t> temp(KEY_BYTES);
91 buffer_insert(temp, KEY_BYTES - coded.size(), coded);
92 coded = temp;
93 }
94
95 const size_t TOP_BITS = 8 * ((key_bits + 7) / 8) - key_bits;
96 if(TOP_BITS > 8 - high_bit(coded[0]))
97 return false;
98
99 uint8_t* DB = coded.data();
100 const size_t DB_size = coded.size() - HASH_SIZE - 1;
101
102 const uint8_t* H = &coded[DB_size];
103 const size_t H_size = HASH_SIZE;
104
105 mgf1_mask(*m_hash, H, H_size, DB, DB_size);
106 DB[0] &= 0xFF >> TOP_BITS;
107
108 size_t salt_offset = 0;
109 for(size_t j = 0; j != DB_size; ++j)
110 {
111 if(DB[j] == 0x01)
112 { salt_offset = j + 1; break; }
113 if(DB[j])
114 return false;
115 }
116 if(salt_offset == 0)
117 return false;
118
119 for(size_t j = 0; j != 8; ++j)
120 m_hash->update(0);
121 m_hash->update(raw);
122 m_hash->update(&DB[salt_offset], DB_size - salt_offset);
123 secure_vector<uint8_t> H2 = m_hash->final();
124
125 return same_mem(H, H2.data(), HASH_SIZE);
126 }
127
128 PSSR::PSSR(HashFunction* h) :
129 m_SALT_SIZE(h->output_length()), m_hash(h)
130 {
131 }
132
133 PSSR::PSSR(HashFunction* h, size_t salt_size) :
134 m_SALT_SIZE(salt_size), m_hash(h)
135 {
136 }
137
138 }
Botan::same_mem
bool same_mem(const T *p1, const T *p2, size_t n)
Definition: mem_ops.h:98
salt_size
size_t salt_size
Definition: p11_mechanism.cpp:69
Botan::high_bit
size_t high_bit(T n)
Definition: bit_ops.h:37
Botan
Definition: alg_id.cpp:13
Botan::HashFunction
Definition: hash.h:19
Botan::mgf1_mask
void mgf1_mask(HashFunction &hash, const uint8_t in[], size_t in_len, uint8_t out[], size_t out_len)
Definition: mgf1.cpp:14
Botan::buffer_insert
size_t buffer_insert(std::vector< T, Alloc > &buf, size_t buf_offset, const T input[], size_t input_length)
Definition: secmem.h:133
Botan::PSSR::PSSR
PSSR(HashFunction *hash)
Definition: pssr.cpp:128
m_hash
std::unique_ptr< HashFunction > m_hash
Definition: tpm.cpp:439