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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
/*
* Salsa20
* (C) 1999-2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/salsa20.h>
#include <botan/mem_ops.h>
#include <botan/xor_buf.h>
#include <botan/loadstor.h>
#include <botan/parsing.h>
namespace Botan {
namespace {
/*
* Generate Salsa20 cipher stream
*/
void salsa20(byte output[64], const u32bit input[16])
{
u32bit x00 = input[0];
u32bit x01 = input[1];
u32bit x02 = input[2];
u32bit x03 = input[3];
u32bit x04 = input[4];
u32bit x05 = input[5];
u32bit x06 = input[6];
u32bit x07 = input[7];
u32bit x08 = input[8];
u32bit x09 = input[9];
u32bit x10 = input[10];
u32bit x11 = input[11];
u32bit x12 = input[12];
u32bit x13 = input[13];
u32bit x14 = input[14];
u32bit x15 = input[15];
for(u32bit i = 0; i != 10; ++i)
{
x04 ^= rotate_left(x00 + x12, 7);
x08 ^= rotate_left(x04 + x00, 9);
x12 ^= rotate_left(x08 + x04, 13);
x00 ^= rotate_left(x12 + x08, 18);
x09 ^= rotate_left(x05 + x01, 7);
x13 ^= rotate_left(x09 + x05, 9);
x01 ^= rotate_left(x13 + x09, 13);
x05 ^= rotate_left(x01 + x13, 18);
x14 ^= rotate_left(x10 + x06, 7);
x02 ^= rotate_left(x14 + x10, 9);
x06 ^= rotate_left(x02 + x14, 13);
x10 ^= rotate_left(x06 + x02, 18);
x03 ^= rotate_left(x15 + x11, 7);
x07 ^= rotate_left(x03 + x15, 9);
x11 ^= rotate_left(x07 + x03, 13);
x15 ^= rotate_left(x11 + x07, 18);
x01 ^= rotate_left(x00 + x03, 7);
x02 ^= rotate_left(x01 + x00, 9);
x03 ^= rotate_left(x02 + x01, 13);
x00 ^= rotate_left(x03 + x02, 18);
x06 ^= rotate_left(x05 + x04, 7);
x07 ^= rotate_left(x06 + x05, 9);
x04 ^= rotate_left(x07 + x06, 13);
x05 ^= rotate_left(x04 + x07, 18);
x11 ^= rotate_left(x10 + x09, 7);
x08 ^= rotate_left(x11 + x10, 9);
x09 ^= rotate_left(x08 + x11, 13);
x10 ^= rotate_left(x09 + x08, 18);
x12 ^= rotate_left(x15 + x14, 7);
x13 ^= rotate_left(x12 + x15, 9);
x14 ^= rotate_left(x13 + x12, 13);
x15 ^= rotate_left(x14 + x13, 18);
}
store_le(x00 + input[ 0], output + 4 * 0);
store_le(x01 + input[ 1], output + 4 * 1);
store_le(x02 + input[ 2], output + 4 * 2);
store_le(x03 + input[ 3], output + 4 * 3);
store_le(x04 + input[ 4], output + 4 * 4);
store_le(x05 + input[ 5], output + 4 * 5);
store_le(x06 + input[ 6], output + 4 * 6);
store_le(x07 + input[ 7], output + 4 * 7);
store_le(x08 + input[ 8], output + 4 * 8);
store_le(x09 + input[ 9], output + 4 * 9);
store_le(x10 + input[10], output + 4 * 10);
store_le(x11 + input[11], output + 4 * 11);
store_le(x12 + input[12], output + 4 * 12);
store_le(x13 + input[13], output + 4 * 13);
store_le(x14 + input[14], output + 4 * 14);
store_le(x15 + input[15], output + 4 * 15);
}
}
/*
* Combine cipher stream with message
*/
void Salsa20::cipher(const byte in[], byte out[], u32bit length)
{
while(length >= buffer.size() - position)
{
xor_buf(out, in, buffer.begin() + position, buffer.size() - position);
length -= (buffer.size() - position);
in += (buffer.size() - position);
out += (buffer.size() - position);
salsa20(buffer.begin(), state);
++state[8];
if(!state[8]) // if overflow in state[8]
++state[9]; // carry to state[9]
position = 0;
}
xor_buf(out, in, buffer.begin() + position, length);
position += length;
}
/*
* Salsa20 Key Schedule
*/
void Salsa20::key_schedule(const byte key[], u32bit length)
{
static const u32bit TAU[] =
{ 0x61707865, 0x3120646e, 0x79622d36, 0x6b206574 };
static const u32bit SIGMA[] =
{ 0x61707865, 0x3320646e, 0x79622d32, 0x6b206574 };
clear();
if(length == 16)
{
state[0] = TAU[0];
state[1] = load_le<u32bit>(key, 0);
state[2] = load_le<u32bit>(key, 1);
state[3] = load_le<u32bit>(key, 2);
state[4] = load_le<u32bit>(key, 3);
state[5] = TAU[1];
state[10] = TAU[2];
state[11] = load_le<u32bit>(key, 0);
state[12] = load_le<u32bit>(key, 1);
state[13] = load_le<u32bit>(key, 2);
state[14] = load_le<u32bit>(key, 3);
state[15] = TAU[3];
}
else if(length == 32)
{
state[0] = SIGMA[0];
state[1] = load_le<u32bit>(key, 0);
state[2] = load_le<u32bit>(key, 1);
state[3] = load_le<u32bit>(key, 2);
state[4] = load_le<u32bit>(key, 3);
state[5] = SIGMA[1];
state[10] = SIGMA[2];
state[11] = load_le<u32bit>(key, 4);
state[12] = load_le<u32bit>(key, 5);
state[13] = load_le<u32bit>(key, 6);
state[14] = load_le<u32bit>(key, 7);
state[15] = SIGMA[3];
}
const byte ZERO[8] = { 0 };
resync(ZERO, sizeof(ZERO));
}
/*
* Return the name of this type
*/
void Salsa20::resync(const byte iv[], u32bit length)
{
if(length != IV_LENGTH)
throw Invalid_IV_Length(name(), length);
state[6] = load_le<u32bit>(iv, 0);
state[7] = load_le<u32bit>(iv, 1);
state[8] = 0;
state[9] = 0;
salsa20(buffer.begin(), state);
++state[8];
if(!state[8]) // if overflow in state[8]
++state[9]; // carry to state[9]
position = 0;
}
/*
* Return the name of this type
*/
std::string Salsa20::name() const
{
return "Salsa20";
}
/*
* Clear memory of sensitive data
*/
void Salsa20::clear() throw()
{
state.clear();
buffer.clear();
position = 0;
}
/*
* Salsa20 Constructor
*/
Salsa20::Salsa20() : StreamCipher(16, 32, 16, 8)
{
clear();
}
}
|
