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
|
/*
* cifra - embedded cryptography library
* Written in 2014 by Joseph Birr-Pixton <jpixton@gmail.com>
*
* To the extent possible under law, the author(s) have dedicated all
* copyright and related and neighboring rights to this software to the
* public domain worldwide. This software is distributed without any
* warranty.
*
* You should have received a copy of the CC0 Public Domain Dedication
* along with this software. If not, see
* <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
#include "salsa20.h"
#include "bitops.h"
#include "blockwise.h"
#include <string.h>
#include <stdlib.h>
void cf_salsa20_core(const uint8_t key0[16],
const uint8_t key1[16],
const uint8_t nonce[16],
const uint8_t constant[16],
uint8_t out[64])
{
/* unpack sequence is:
*
* c0
* key0
* c1
* nonce
* c2
* key1
* c3
*
* where c0, c1, c2, c3 = constant
*/
uint32_t z0, z1, z2, z3, z4, z5, z6, z7,
z8, z9, za, zb, zc, zd, ze, zf;
uint32_t x0 = z0 = read32_le(constant + 0),
x1 = z1 = read32_le(key0 + 0),
x2 = z2 = read32_le(key0 + 4),
x3 = z3 = read32_le(key0 + 8),
x4 = z4 = read32_le(key0 + 12),
x5 = z5 = read32_le(constant + 4),
x6 = z6 = read32_le(nonce + 0),
x7 = z7 = read32_le(nonce + 4),
x8 = z8 = read32_le(nonce + 8),
x9 = z9 = read32_le(nonce + 12),
xa = za = read32_le(constant + 8),
xb = zb = read32_le(key1 + 0),
xc = zc = read32_le(key1 + 4),
xd = zd = read32_le(key1 + 8),
xe = ze = read32_le(key1 + 12),
xf = zf = read32_le(constant + 12);
#define QUARTER(v0, v1, v2, v3) \
v1 ^= rotl32(v0 + v3, 7); \
v2 ^= rotl32(v1 + v0, 9); \
v3 ^= rotl32(v2 + v1, 13);\
v0 ^= rotl32(v3 + v2, 18)
#define ROW \
QUARTER(z0, z1, z2, z3); \
QUARTER(z5, z6, z7, z4); \
QUARTER(za, zb, z8, z9); \
QUARTER(zf, zc, zd, ze)
#define COLUMN\
QUARTER(z0, z4, z8, zc); \
QUARTER(z5, z9, zd, z1); \
QUARTER(za, ze, z2, z6); \
QUARTER(zf, z3, z7, zb)
for (int i = 0; i < 10; i++)
{
COLUMN;
ROW;
}
x0 += z0;
x1 += z1;
x2 += z2;
x3 += z3;
x4 += z4;
x5 += z5;
x6 += z6;
x7 += z7;
x8 += z8;
x9 += z9;
xa += za;
xb += zb;
xc += zc;
xd += zd;
xe += ze;
xf += zf;
write32_le(x0, out + 0);
write32_le(x1, out + 4);
write32_le(x2, out + 8);
write32_le(x3, out + 12);
write32_le(x4, out + 16);
write32_le(x5, out + 20);
write32_le(x6, out + 24);
write32_le(x7, out + 28);
write32_le(x8, out + 32);
write32_le(x9, out + 36);
write32_le(xa, out + 40);
write32_le(xb, out + 44);
write32_le(xc, out + 48);
write32_le(xd, out + 52);
write32_le(xe, out + 56);
write32_le(xf, out + 60);
}
static const uint8_t *salsa20_tau = (const uint8_t *) "expand 16-byte k";
static const uint8_t *salsa20_sigma = (const uint8_t *) "expand 32-byte k";
void cf_salsa20_init(cf_salsa20_ctx *ctx, const uint8_t *key, size_t nkey, const uint8_t nonce[8])
{
switch (nkey)
{
case 16:
memcpy(ctx->key0, key, 16);
memcpy(ctx->key1, key, 16);
ctx->constant = salsa20_tau;
break;
case 32:
memcpy(ctx->key0, key, 16);
memcpy(ctx->key1, key + 16, 16);
ctx->constant = salsa20_sigma;
break;
default:
abort();
}
memset(ctx->nonce, 0, sizeof ctx->nonce);
memcpy(ctx->nonce + 8, nonce, 8);
ctx->nblock = 0;
ctx->ncounter = 8;
}
static void cf_salsa20_next_block(void *vctx, uint8_t *out)
{
cf_salsa20_ctx *ctx = vctx;
cf_salsa20_core(ctx->key0,
ctx->key1,
ctx->nonce,
ctx->constant,
out);
incr_le(ctx->nonce, ctx->ncounter);
}
void cf_salsa20_cipher(cf_salsa20_ctx *ctx, const uint8_t *input, uint8_t *output, size_t bytes)
{
cf_blockwise_xor(ctx->block, &ctx->nblock, 64,
input, output, bytes,
cf_salsa20_next_block,
ctx);
}
|
