summaryrefslogtreecommitdiff
path: root/sys/crypto/gmac.c
blob: 33843d08fbe291d8d7a111c53f519e438c75bd4e (plain)
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
/*	$OpenBSD: gmac.c,v 1.9 2016/09/19 18:09:40 tedu Exp $	*/

/*
 * Copyright (c) 2010 Mike Belopuhov
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * This code implements the Message Authentication part of the
 * Galois/Counter Mode (as being described in the RFC 4543) using
 * the AES cipher.  FIPS SP 800-38D describes the algorithm details.
 */

#include <sys/param.h>
#include <sys/systm.h>

#include <crypto/rijndael.h>
#include <crypto/gmac.h>

void	ghash_gfmul(uint32_t *, uint32_t *, uint32_t *);
void	ghash_update_mi(GHASH_CTX *, uint8_t *, size_t);

/* Allow overriding with optimized MD function */
void	(*ghash_update)(GHASH_CTX *, uint8_t *, size_t) = ghash_update_mi;

/* Computes a block multiplication in the GF(2^128) */
void
ghash_gfmul(uint32_t *X, uint32_t *Y, uint32_t *product)
{
	uint32_t	v[4];
	uint32_t	z[4] = { 0, 0, 0, 0};
	uint8_t		*x = (uint8_t *)X;
	uint32_t	mask;
	int		i;

	v[0] = betoh32(Y[0]);
	v[1] = betoh32(Y[1]);
	v[2] = betoh32(Y[2]);
	v[3] = betoh32(Y[3]);

	for (i = 0; i < GMAC_BLOCK_LEN * 8; i++) {
		/* update Z */
		mask = !!(x[i >> 3] & (1 << (~i & 7)));
		mask = ~(mask - 1);
		z[0] ^= v[0] & mask;
		z[1] ^= v[1] & mask;
		z[2] ^= v[2] & mask;
		z[3] ^= v[3] & mask;

		/* update V */
		mask = ~((v[3] & 1) - 1);
		v[3] = (v[2] << 31) | (v[3] >> 1);
		v[2] = (v[1] << 31) | (v[2] >> 1);
		v[1] = (v[0] << 31) | (v[1] >> 1);
		v[0] = (v[0] >> 1) ^ (0xe1000000 & mask);
	}

	product[0] = htobe32(z[0]);
	product[1] = htobe32(z[1]);
	product[2] = htobe32(z[2]);
	product[3] = htobe32(z[3]);
}

void
ghash_update_mi(GHASH_CTX *ctx, uint8_t *X, size_t len)
{
	uint32_t	*x = (uint32_t *)X;
	uint32_t	*s = (uint32_t *)ctx->S;
	uint32_t	*y = (uint32_t *)ctx->Z;
	int		i;

	for (i = 0; i < len / GMAC_BLOCK_LEN; i++) {
		s[0] = y[0] ^ x[0];
		s[1] = y[1] ^ x[1];
		s[2] = y[2] ^ x[2];
		s[3] = y[3] ^ x[3];

		ghash_gfmul((uint32_t *)ctx->S, (uint32_t *)ctx->H,
		    (uint32_t *)ctx->S);

		y = s;
		x += 4;
	}

	bcopy(ctx->S, ctx->Z, GMAC_BLOCK_LEN);
}

#define AESCTR_NONCESIZE	4

void
AES_GMAC_Init(void *xctx)
{
	AES_GMAC_CTX	*ctx = xctx;

	bzero(ctx->ghash.H, GMAC_BLOCK_LEN);
	bzero(ctx->ghash.S, GMAC_BLOCK_LEN);
	bzero(ctx->ghash.Z, GMAC_BLOCK_LEN);
	bzero(ctx->J, GMAC_BLOCK_LEN);
}

void
AES_GMAC_Setkey(void *xctx, const uint8_t *key, uint16_t klen)
{
	AES_GMAC_CTX	*ctx = xctx;

	ctx->rounds = rijndaelKeySetupEnc(ctx->K, (u_char *)key,
	    (klen - AESCTR_NONCESIZE) * 8);
	/* copy out salt to the counter block */
	bcopy(key + klen - AESCTR_NONCESIZE, ctx->J, AESCTR_NONCESIZE);
	/* prepare a hash subkey */
	rijndaelEncrypt(ctx->K, ctx->rounds, ctx->ghash.H, ctx->ghash.H);
}

void
AES_GMAC_Reinit(void *xctx, const uint8_t *iv, uint16_t ivlen)
{
	AES_GMAC_CTX	*ctx = xctx;

	/* copy out IV to the counter block */
	bcopy(iv, ctx->J + AESCTR_NONCESIZE, ivlen);
}

int
AES_GMAC_Update(void *xctx, const uint8_t *data, uint16_t len)
{
	AES_GMAC_CTX	*ctx = xctx;
	uint32_t	blk[4] = { 0, 0, 0, 0 };
	int		plen;

	if (len > 0) {
		plen = len % GMAC_BLOCK_LEN;
		if (len >= GMAC_BLOCK_LEN)
			(*ghash_update)(&ctx->ghash, (uint8_t *)data,
			    len - plen);
		if (plen) {
			memcpy((uint8_t *)blk, (uint8_t *)data + (len - plen),
			    plen);
			(*ghash_update)(&ctx->ghash, (uint8_t *)blk,
			    GMAC_BLOCK_LEN);
		}
	}
	return (0);
}

void
AES_GMAC_Final(uint8_t digest[GMAC_DIGEST_LEN], void *xctx)
{
	AES_GMAC_CTX	*ctx = xctx;
	uint8_t		keystream[GMAC_BLOCK_LEN];
	int		i;

	/* do one round of GCTR */
	ctx->J[GMAC_BLOCK_LEN - 1] = 1;
	rijndaelEncrypt(ctx->K, ctx->rounds, ctx->J, keystream);
	for (i = 0; i < GMAC_DIGEST_LEN; i++)
		digest[i] = ctx->ghash.S[i] ^ keystream[i];
	explicit_bzero(keystream, sizeof(keystream));
}