1 /* umac32.c
2
3 Copyright (C) 2013 Niels Möller
4
5 This file is part of GNU Nettle.
6
7 GNU Nettle is free software: you can redistribute it and/or
8 modify it under the terms of either:
9
10 * the GNU Lesser General Public License as published by the Free
11 Software Foundation; either version 3 of the License, or (at your
12 option) any later version.
13
14 or
15
16 * the GNU General Public License as published by the Free
17 Software Foundation; either version 2 of the License, or (at your
18 option) any later version.
19
20 or both in parallel, as here.
21
22 GNU Nettle is distributed in the hope that it will be useful,
23 but WITHOUT ANY WARRANTY; without even the implied warranty of
24 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
25 General Public License for more details.
26
27 You should have received copies of the GNU General Public License and
28 the GNU Lesser General Public License along with this program. If
29 not, see http://www.gnu.org/licenses/.
30 */
31
32 #if HAVE_CONFIG_H
33 # include "config.h"
34 #endif
35
36 #include <assert.h>
37 #include <string.h>
38
39 #include "umac.h"
40 #include "umac-internal.h"
41
42 #include "macros.h"
43
44 void
umac32_set_key(struct umac32_ctx * ctx,const uint8_t * key)45 umac32_set_key (struct umac32_ctx *ctx, const uint8_t *key)
46 {
47 _umac_set_key (ctx->l1_key, ctx->l2_key, ctx->l3_key1, ctx->l3_key2,
48 &ctx->pdf_key, key, 1);
49
50 /* Clear nonce */
51 memset (ctx->nonce, 0, sizeof(ctx->nonce));
52 ctx->nonce_low = 0;
53 ctx->nonce_length = sizeof(ctx->nonce);
54
55 /* Initialize buffer */
56 ctx->count = ctx->index = 0;
57 }
58
59 void
umac32_set_nonce(struct umac32_ctx * ctx,size_t nonce_length,const uint8_t * nonce)60 umac32_set_nonce (struct umac32_ctx *ctx,
61 size_t nonce_length, const uint8_t *nonce)
62 {
63 assert (nonce_length > 0);
64 assert (nonce_length <= AES_BLOCK_SIZE);
65
66 memcpy (ctx->nonce, nonce, nonce_length);
67 memset (ctx->nonce + nonce_length, 0, AES_BLOCK_SIZE - nonce_length);
68
69 ctx->nonce_low = ctx->nonce[nonce_length - 1] & 3;
70 ctx->nonce[nonce_length - 1] &= ~3;
71 ctx->nonce_length = nonce_length;
72 }
73
74 #define UMAC32_BLOCK(ctx, block) do { \
75 uint64_t __umac32_y \
76 = _umac_nh (ctx->l1_key, UMAC_BLOCK_SIZE, block) \
77 + 8*UMAC_BLOCK_SIZE ; \
78 _umac_l2 (ctx->l2_key, ctx->l2_state, 1, ctx->count++, &__umac32_y); \
79 } while (0)
80
81 void
umac32_update(struct umac32_ctx * ctx,size_t length,const uint8_t * data)82 umac32_update (struct umac32_ctx *ctx,
83 size_t length, const uint8_t *data)
84 {
85 MD_UPDATE (ctx, length, data, UMAC32_BLOCK, (void)0);
86 }
87
88
89 void
umac32_digest(struct umac32_ctx * ctx,size_t length,uint8_t * digest)90 umac32_digest (struct umac32_ctx *ctx,
91 size_t length, uint8_t *digest)
92 {
93 uint32_t pad;
94
95 assert (length > 0);
96 assert (length <= 4);
97
98 if (ctx->index > 0 || ctx->count == 0)
99 {
100 /* Zero pad to multiple of 32 */
101 uint64_t y;
102 unsigned pad = (ctx->index > 0) ? 31 & - ctx->index : 32;
103 memset (ctx->block + ctx->index, 0, pad);
104
105 y = _umac_nh (ctx->l1_key, ctx->index + pad, ctx->block)
106 + 8 * ctx->index;
107 _umac_l2 (ctx->l2_key, ctx->l2_state, 1, ctx->count++, &y);
108 }
109 assert (ctx->count > 0);
110 if ( !(ctx->nonce_low & _UMAC_NONCE_CACHED))
111 {
112 aes128_encrypt (&ctx->pdf_key, AES_BLOCK_SIZE,
113 (uint8_t *) ctx->pad_cache, ctx->nonce);
114 ctx->nonce_low |= _UMAC_NONCE_CACHED;
115 }
116
117 pad = ctx->pad_cache[ctx->nonce_low & 3];
118
119 /* Increment nonce */
120 ctx->nonce_low++;
121 if ( !(ctx->nonce_low & 3))
122 {
123 unsigned i = ctx->nonce_length - 1;
124
125 ctx->nonce_low = 0;
126 ctx->nonce[i] += 4;
127
128 if (ctx->nonce[i] == 0 && i > 0)
129 INCREMENT (i, ctx->nonce);
130 }
131
132 _umac_l2_final (ctx->l2_key, ctx->l2_state, 1, ctx->count);
133 pad ^= ctx->l3_key2[0] ^ _umac_l3 (ctx->l3_key1, ctx->l2_state);
134 memcpy (digest, &pad, length);
135
136 /* Reinitialize */
137 ctx->count = ctx->index = 0;
138 }
139