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
|
/* skein512.c
Copyright (C) 2016, 2017, 2018 Niels Möller
This file is part of GNU Nettle.
GNU Nettle is free software: you can redistribute it and/or
modify it under the terms of either:
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
or
* the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.
or both in parallel, as here.
GNU Nettle is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see http://www.gnu.org/licenses/.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <string.h>
#include "skein.h"
#include "nettle-write.h"
void
_skein512_expand(uint64_t keys[_SKEIN512_NKEYS])
{
uint64_t sum;
unsigned i;
for (i = 0, sum = _SKEIN_C240; i < _SKEIN512_LENGTH; i++)
sum ^= keys[i];
keys[_SKEIN512_LENGTH] = sum;
/* Repeat keys, for simpler indexing. */
for (i = _SKEIN512_LENGTH + 1; i < _SKEIN512_NKEYS; i++)
keys[i] = keys[i-9];
}
void
skein512_init(struct skein512_ctx *ctx)
{
static const uint64_t G0[_SKEIN512_LENGTH] = {
0x4903ADFF749C51CEull, 0x0D95DE399746DF03ull,
0x8FD1934127C79BCEull, 0x9A255629FF352CB1ull,
0x5DB62599DF6CA7B0ull, 0xEABE394CA9D5C3F4ull,
0x991112C71A75B523ull, 0xAE18A40B660FCC33ull,
};
memcpy (ctx->state, G0, sizeof(G0));
ctx->count = 0;
ctx->index = 0;
}
static void
skein512_process_block(struct skein512_ctx *ctx,
unsigned tag, unsigned length,
const uint8_t *data)
{
/* Expand key */
uint64_t tweak[_SKEIN_NTWEAK];
tag |= ((ctx->count == 0) << 6);
tweak[0] = (ctx->count << 6) + length;
tweak[1] = (ctx->count >> 58) | ((uint64_t) tag << 56);
_skein512_expand(ctx->state);
_skein512_block(ctx->state, ctx->state, tweak, data);
ctx->count++;
/* Wraparound not handled (limited message size). */
assert (ctx->count > 0);
}
void
skein512_update(struct skein512_ctx *ctx,
size_t length,
const uint8_t *data)
{
if (ctx->index > 0)
{
unsigned left = SKEIN512_BLOCK_SIZE - ctx->index;
if (length <= left)
{
memcpy (ctx->block + ctx->index, data, length);
ctx->index += length;
return;
}
memcpy (ctx->block + ctx->index, data, left);
data += left;
length -= left;
assert (length > 0);
skein512_process_block(ctx, 0x30, SKEIN512_BLOCK_SIZE, ctx->block);
}
while (length > SKEIN512_BLOCK_SIZE)
{
skein512_process_block(ctx, 0x30, SKEIN512_BLOCK_SIZE, data);
data += SKEIN512_BLOCK_SIZE;
length -= SKEIN512_BLOCK_SIZE;
}
assert (length <= SKEIN512_BLOCK_SIZE);
memcpy (ctx->block, data, length);
ctx->index = length;
}
void
skein512_digest(struct skein512_ctx *ctx,
size_t length,
uint8_t *digest)
{
static const uint8_t zeros[SKEIN512_BLOCK_SIZE];
/* FIXME: Should be always true. */
if (ctx->index > 0 || ctx->count == 0)
{
memset (ctx->block + ctx->index, 0,
SKEIN512_BLOCK_SIZE - ctx->index);
skein512_process_block(ctx, 0xb0, ctx->index, ctx->block);
}
/* Reset count for output processing. */
ctx->count = 0;
skein512_process_block(ctx, 0xff, 8, zeros);
_nettle_write_le64(length, digest, ctx->state);
skein512_init(ctx);
}
|
