Botan 2.1.0 Crypto and TLS for C++11

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comb4p.cpp
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1 /*
2 * Comb4P hash combiner
3 * (C) 2010 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7
8 #include <botan/comb4p.h>
9 #include <botan/exceptn.h>
10
11 namespace Botan {
12
13 namespace {
14
15 void comb4p_round(secure_vector<uint8_t>& out,
16 const secure_vector<uint8_t>& in,
17 uint8_t round_no,
18 HashFunction& h1,
19 HashFunction& h2)
20 {
21 h1.update(round_no);
22 h2.update(round_no);
23
24 h1.update(in.data(), in.size());
25 h2.update(in.data(), in.size());
26
27 secure_vector<uint8_t> h_buf = h1.final();
28 xor_buf(out.data(), h_buf.data(), std::min(out.size(), h_buf.size()));
29
30 h_buf = h2.final();
31 xor_buf(out.data(), h_buf.data(), std::min(out.size(), h_buf.size()));
32 }
33
34 }
35
36 Comb4P::Comb4P(HashFunction* h1, HashFunction* h2) :
37 m_hash1(h1), m_hash2(h2)
38 {
39 if(m_hash1->name() == m_hash2->name())
40 throw Invalid_Argument("Comb4P: Must use two distinct hashes");
41
42 if(m_hash1->output_length() != m_hash2->output_length())
43 throw Invalid_Argument("Comb4P: Incompatible hashes " +
44 m_hash1->name() + " and " +
45 m_hash2->name());
46
47 clear();
48 }
49
50 size_t Comb4P::hash_block_size() const
51 {
52 if(m_hash1->hash_block_size() == m_hash2->hash_block_size())
53 return m_hash1->hash_block_size();
54
55 /*
56 * Return LCM of the block sizes? This would probably be OK for
57 * HMAC, which is the main thing relying on knowing the block size.
58 */
59 return 0;
60 }
61
62 void Comb4P::clear()
63 {
64 m_hash1->clear();
65 m_hash2->clear();
66
67 // Prep for processing next message, if any
68 m_hash1->update(0);
69 m_hash2->update(0);
70 }
71
72 void Comb4P::add_data(const uint8_t input[], size_t length)
73 {
74 m_hash1->update(input, length);
75 m_hash2->update(input, length);
76 }
77
78 void Comb4P::final_result(uint8_t out[])
79 {
80 secure_vector<uint8_t> h1 = m_hash1->final();
81 secure_vector<uint8_t> h2 = m_hash2->final();
82
83 // First round
84 xor_buf(h1.data(), h2.data(), std::min(h1.size(), h2.size()));
85
86 // Second round
87 comb4p_round(h2, h1, 1, *m_hash1, *m_hash2);
88
89 // Third round
90 comb4p_round(h1, h2, 2, *m_hash1, *m_hash2);
91
92 copy_mem(out , h1.data(), h1.size());
93 copy_mem(out + h1.size(), h2.data(), h2.size());
94
95 // Prep for processing next message, if any
96 m_hash1->update(0);
97 m_hash2->update(0);
98 }
99
100 }
101
Botan::xor_buf
void xor_buf(T out[], const T in[], size_t length)
Definition: mem_ops.h:115
Botan::Comb4P::Comb4P
Comb4P(HashFunction *h1, HashFunction *h2)
Definition: comb4p.cpp:36
Botan::Invalid_Argument
Definition: exceptn.h:34
Botan::copy_mem
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:68
Botan
Definition: alg_id.cpp:13
Botan::Comb4P::clear
void clear() override
Definition: comb4p.cpp:62
Botan::HashFunction
Definition: hash.h:19
Botan::Comb4P::hash_block_size
size_t hash_block_size() const override
Definition: comb4p.cpp:50
Botan::CT::min
T min(T a, T b)
Definition: ct_utils.h:180