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
140
141
|
// cmac.cpp - originally written and placed in the public domain by Wei Dai
#include "pch.h"
#ifndef CRYPTOPP_IMPORTS
#include "cmac.h"
NAMESPACE_BEGIN(CryptoPP)
static void MulU(byte *k, unsigned int length)
{
byte carry = 0;
for (int i=length-1; i>=1; i-=2)
{
byte carry2 = k[i] >> 7;
k[i] += k[i] + carry;
carry = k[i-1] >> 7;
k[i-1] += k[i-1] + carry2;
}
if (carry)
{
switch (length)
{
case 8:
k[7] ^= 0x1b;
break;
case 16:
k[15] ^= 0x87;
break;
case 32:
// https://crypto.stackexchange.com/q/9815/10496
// Polynomial x^256 + x^10 + x^5 + x^2 + 1
k[30] ^= 4;
k[31] ^= 0x25;
break;
case 64:
// https://crypto.stackexchange.com/q/9815/10496
// Polynomial x^512 + x^8 + x^5 + x^2 + 1
k[62] ^= 1;
k[63] ^= 0x25;
break;
case 128:
// https://crypto.stackexchange.com/q/9815/10496
// Polynomial x^1024 + x^19 + x^6 + x + 1
k[125] ^= 8;
k[126] ^= 0x00;
k[127] ^= 0x43;
break;
default:
throw InvalidArgument("CMAC: " + IntToString(length) + " is not a supported cipher block size");
}
}
}
void CMAC_Base::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs ¶ms)
{
BlockCipher &cipher = AccessCipher();
cipher.SetKey(key, length, params);
unsigned int blockSize = cipher.BlockSize();
m_reg.CleanNew(3*blockSize);
m_counter = 0;
cipher.ProcessBlock(m_reg, m_reg+blockSize);
MulU(m_reg+blockSize, blockSize);
memcpy(m_reg+2*blockSize, m_reg+blockSize, blockSize);
MulU(m_reg+2*blockSize, blockSize);
}
void CMAC_Base::Update(const byte *input, size_t length)
{
CRYPTOPP_ASSERT((input && length) || !(input || length));
if (!length)
return;
BlockCipher &cipher = AccessCipher();
unsigned int blockSize = cipher.BlockSize();
if (m_counter > 0)
{
const unsigned int len = UnsignedMin(blockSize - m_counter, length);
if (len)
{
xorbuf(m_reg+m_counter, input, len);
length -= len;
input += len;
m_counter += len;
}
if (m_counter == blockSize && length > 0)
{
cipher.ProcessBlock(m_reg);
m_counter = 0;
}
}
if (length > blockSize)
{
CRYPTOPP_ASSERT(m_counter == 0);
size_t leftOver = 1 + cipher.AdvancedProcessBlocks(m_reg, input, m_reg, length-1, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
input += (length - leftOver);
length = leftOver;
}
if (length > 0)
{
CRYPTOPP_ASSERT(m_counter + length <= blockSize);
xorbuf(m_reg+m_counter, input, length);
m_counter += (unsigned int)length;
}
CRYPTOPP_ASSERT(m_counter > 0);
}
void CMAC_Base::TruncatedFinal(byte *mac, size_t size)
{
ThrowIfInvalidTruncatedSize(size);
BlockCipher &cipher = AccessCipher();
unsigned int blockSize = cipher.BlockSize();
if (m_counter < blockSize)
{
m_reg[m_counter] ^= 0x80;
cipher.AdvancedProcessBlocks(m_reg, m_reg+2*blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
}
else
cipher.AdvancedProcessBlocks(m_reg, m_reg+blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
memcpy(mac, m_reg, size);
m_counter = 0;
memset(m_reg, 0, blockSize);
}
NAMESPACE_END
#endif
|
