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
218
219
220
221
222
|
/*
* Simple implementation of chacha20 used as a CSPRNG.
*
* Copyright (c) 2016 NORDUnet A/S
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
* 3. Neither the name of the NORDUnet nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "cc20_prng.h"
/* "expand 32-byte k" */
#define CHACHA20_CONSTANT0 0x61707865
#define CHACHA20_CONSTANT1 0x3320646e
#define CHACHA20_CONSTANT2 0x79622d32
#define CHACHA20_CONSTANT3 0x6b206574
#ifdef CHACHA20_PRNG_DEBUG
void _dump(struct cc20_state *cc, char *str);
#endif
inline uint32_t rotl32(uint32_t x, uint32_t n)
{
return (x << n) | (x >> (32 - n));
}
inline void _qr(struct cc20_state *cc, uint32_t a, uint32_t b, uint32_t c,
uint32_t d)
{
cc->i[a] += cc->i[b];
cc->i[d] ^= cc->i[a];
cc->i[d] = rotl32(cc->i[d], 16);
cc->i[c] += cc->i[d];
cc->i[b] ^= cc->i[c];
cc->i[b] = rotl32(cc->i[b], 12);
cc->i[a] += cc->i[b];
cc->i[d] ^= cc->i[a];
cc->i[d] = rotl32(cc->i[d], 8);
cc->i[c] += cc->i[d];
cc->i[b] ^= cc->i[c];
cc->i[b] = rotl32(cc->i[b], 7);
}
void chacha20_prng_reseed(struct cc20_state *cc, uint32_t *entropy)
{
uint32_t i = 256 / 8 / 4;
while (i--) {
cc->i[i] = entropy[i];
}
}
void chacha20_prng_block(struct cc20_state *cc, uint32_t block_counter,
struct cc20_state *out)
{
uint32_t i;
out->i[0] = CHACHA20_CONSTANT0;
out->i[1] = CHACHA20_CONSTANT1;
out->i[2] = CHACHA20_CONSTANT2;
out->i[3] = CHACHA20_CONSTANT3;
cc->i[12] = block_counter;
for (i = 4; i < CHACHA20_NUM_WORDS; i++) {
out->i[i] = cc->i[i];
}
for (i = 10; i; i--) {
_qr(out, 0, 4, 8, 12);
_qr(out, 1, 5, 9, 13);
_qr(out, 2, 6, 10, 14);
_qr(out, 3, 7, 11, 15);
_qr(out, 0, 5, 10, 15);
_qr(out, 1, 6, 11, 12);
_qr(out, 2, 7, 8, 13);
_qr(out, 3, 4, 9, 14);
}
for (i = 0; i < CHACHA20_NUM_WORDS; i++) {
out->i[i] += cc->i[i];
}
}
int chacha20_prng_self_test1()
{
/* Test vector from RFC7539, section 2.3.2.
* https://tools.ietf.org/html/rfc7539#section-2.3.2
*/
struct cc20_state test = {
{0x61707865, 0x3320646e, 0x79622d32, 0x6b206574,
0x03020100, 0x07060504, 0x0b0a0908, 0x0f0e0d0c,
0x13121110, 0x17161514, 0x1b1a1918, 0x1f1e1d1c,
0x00000001, 0x09000000, 0x4a000000, 0x00000000,
}};
struct cc20_state expected = {
{0xe4e7f110, 0x15593bd1, 0x1fdd0f50, 0xc47120a3,
0xc7f4d1c7, 0x0368c033, 0x9aaa2204, 0x4e6cd4c3,
0x466482d2, 0x09aa9f07, 0x05d7c214, 0xa2028bd9,
0xd19c12b5, 0xb94e16de, 0xe883d0cb, 0x4e3c50a2,
}};
uint32_t i;
struct cc20_state out;
#ifdef CHACHA20_PRNG_DEBUG
_dump(&test, "Test vector from RFC7539, section 2.3.2. Input:");
#endif
chacha20_prng_block(&test, 1, &out);
#ifdef CHACHA20_PRNG_DEBUG
_dump(&out, "Test vector from RFC7539, section 2.3.2. Output:");
#endif
for (i = 0; i < CHACHA20_NUM_WORDS; i++) {
if (out.i[i] != expected.i[i])
return 0;
}
return 1;
}
int chacha20_prng_self_test2()
{
/* Two-block test vector from RFC7539, section 2.4.2.
* https://tools.ietf.org/html/rfc7539#section-2.4.2
*/
struct cc20_state test = {
{0x61707865, 0x3320646e, 0x79622d32, 0x6b206574,
0x03020100, 0x07060504, 0x0b0a0908, 0x0f0e0d0c,
0x13121110, 0x17161514, 0x1b1a1918, 0x1f1e1d1c,
0x00000001, 0x00000000, 0x4a000000, 0x00000000,
}};
struct cc20_state expected1 = {
{0xf3514f22, 0xe1d91b40, 0x6f27de2f, 0xed1d63b8,
0x821f138c, 0xe2062c3d, 0xecca4f7e, 0x78cff39e,
0xa30a3b8a, 0x920a6072, 0xcd7479b5, 0x34932bed,
0x40ba4c79, 0xcd343ec6, 0x4c2c21ea, 0xb7417df0,
}};
struct cc20_state expected2 = {
{0x9f74a669, 0x410f633f, 0x28feca22, 0x7ec44dec,
0x6d34d426, 0x738cb970, 0x3ac5e9f3, 0x45590cc4,
0xda6e8b39, 0x892c831a, 0xcdea67c1, 0x2b7e1d90,
0x037463f3, 0xa11a2073, 0xe8bcfb88, 0xedc49139,
}};
struct cc20_state out;
uint32_t i;
#ifdef CHACHA20_PRNG_DEBUG
_dump(&test, "Test vector from RFC7539, section 2.4.2. Input:");
#endif
chacha20_prng_block(&test, 1, &out);
#ifdef CHACHA20_PRNG_DEBUG
_dump(&out, "First block");
#endif
for (i = 0; i < CHACHA20_NUM_WORDS; i++) {
if (out.i[i] != expected1.i[i])
return 0;
}
chacha20_prng_block(&test, 2, &out);
#ifdef CHACHA20_PRNG_DEBUG
_dump(&out, "Second block");
#endif
for (i = 0; i < CHACHA20_NUM_WORDS; i++) {
if (out.i[i] != expected2.i[i])
return 0;
}
return 1;
}
#ifdef CHACHA20_PRNG_DEBUG
#include <stdio.h>
void _dump(struct cc20_state *cc, char *str)
{
uint32_t i;
printf("%s\n", str);
for (i = 0; i < 4; i++) {
printf("%02i %08x %08x %08x %08x\n", i * 4, cc->i[i * 4 + 0],
cc->i[i * 4 + 1], cc->i[i * 4 + 2], cc->i[i * 4 + 3]);
}
printf("\n");
}
#endif
/* Test vector from RFC, used as simple power-on self-test of ability to compute
* a block correctly.
*/
int chacha20_prng_self_test()
{
return chacha20_prng_self_test1() && chacha20_prng_self_test2();
}
|
