1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
/*
* CMAC
* (C) 1999-2007,2014 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/cmac.h>
#include <botan/exceptn.h>
#include <botan/internal/poly_dbl.h>
namespace Botan {
/*
* Perform CMAC's multiplication in GF(2^n)
*/
secure_vector<uint8_t> CMAC::poly_double(const secure_vector<uint8_t>& in)
{
secure_vector<uint8_t> out(in.size());
poly_double_n(out.data(), in.data(), out.size());
return out;
}
/*
* Update an CMAC Calculation
*/
void CMAC::add_data(const uint8_t input[], size_t length)
{
const size_t bs = output_length();
buffer_insert(m_buffer, m_position, input, length);
if(m_position + length > bs)
{
xor_buf(m_state, m_buffer, bs);
m_cipher->encrypt(m_state);
input += (bs - m_position);
length -= (bs - m_position);
while(length > bs)
{
xor_buf(m_state, input, bs);
m_cipher->encrypt(m_state);
input += bs;
length -= bs;
}
copy_mem(m_buffer.data(), input, length);
m_position = 0;
}
m_position += length;
}
/*
* Finalize an CMAC Calculation
*/
void CMAC::final_result(uint8_t mac[])
{
xor_buf(m_state, m_buffer, m_position);
if(m_position == output_length())
{
xor_buf(m_state, m_B, output_length());
}
else
{
m_state[m_position] ^= 0x80;
xor_buf(m_state, m_P, output_length());
}
m_cipher->encrypt(m_state);
copy_mem(mac, m_state.data(), output_length());
zeroise(m_state);
zeroise(m_buffer);
m_position = 0;
}
/*
* CMAC Key Schedule
*/
void CMAC::key_schedule(const uint8_t key[], size_t length)
{
clear();
m_cipher->set_key(key, length);
m_cipher->encrypt(m_B);
poly_double_n(m_B.data(), m_B.size());
poly_double_n(m_P.data(), m_B.data(), m_P.size());
}
/*
* Clear memory of sensitive data
*/
void CMAC::clear()
{
m_cipher->clear();
zeroise(m_state);
zeroise(m_buffer);
zeroise(m_B);
zeroise(m_P);
m_position = 0;
}
/*
* Return the name of this type
*/
std::string CMAC::name() const
{
return "CMAC(" + m_cipher->name() + ")";
}
/*
* Return a clone of this object
*/
MessageAuthenticationCode* CMAC::clone() const
{
return new CMAC(m_cipher->clone());
}
/*
* CMAC Constructor
*/
CMAC::CMAC(BlockCipher* cipher) :
m_cipher(cipher),
m_block_size(m_cipher->block_size())
{
if(poly_double_supported_size(m_block_size) == false)
{
throw Invalid_Argument("CMAC cannot use the " +
std::to_string(m_block_size * 8) +
" bit cipher " + m_cipher->name());
}
m_state.resize(output_length());
m_buffer.resize(output_length());
m_B.resize(output_length());
m_P.resize(output_length());
m_position = 0;
}
}
|
