1/* $OpenBSD: hmac.c,v 1.14 2020/02/26 13:40:09 jsg Exp $ */
2/*
3 * Copyright (c) 2014 Markus Friedl.  All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include "includes.h"
19
20#include <sys/types.h>
21
22#include <stdlib.h>
23#include <string.h>
24
25#include "sshbuf.h"
26#include "digest.h"
27#include "hmac.h"
28
29struct ssh_hmac_ctx {
30	int			 alg;
31	struct ssh_digest_ctx	*ictx;
32	struct ssh_digest_ctx	*octx;
33	struct ssh_digest_ctx	*digest;
34	u_char			*buf;
35	size_t			 buf_len;
36};
37
38size_t
39ssh_hmac_bytes(int alg)
40{
41	return ssh_digest_bytes(alg);
42}
43
44struct ssh_hmac_ctx *
45ssh_hmac_start(int alg)
46{
47	struct ssh_hmac_ctx	*ret;
48
49	if ((ret = calloc(1, sizeof(*ret))) == NULL)
50		return NULL;
51	ret->alg = alg;
52	if ((ret->ictx = ssh_digest_start(alg)) == NULL ||
53	    (ret->octx = ssh_digest_start(alg)) == NULL ||
54	    (ret->digest = ssh_digest_start(alg)) == NULL)
55		goto fail;
56	ret->buf_len = ssh_digest_blocksize(ret->ictx);
57	if ((ret->buf = calloc(1, ret->buf_len)) == NULL)
58		goto fail;
59	return ret;
60fail:
61	ssh_hmac_free(ret);
62	return NULL;
63}
64
65int
66ssh_hmac_init(struct ssh_hmac_ctx *ctx, const void *key, size_t klen)
67{
68	size_t i;
69
70	/* reset ictx and octx if no is key given */
71	if (key != NULL) {
72		/* truncate long keys */
73		if (klen <= ctx->buf_len)
74			memcpy(ctx->buf, key, klen);
75		else if (ssh_digest_memory(ctx->alg, key, klen, ctx->buf,
76		    ctx->buf_len) < 0)
77			return -1;
78		for (i = 0; i < ctx->buf_len; i++)
79			ctx->buf[i] ^= 0x36;
80		if (ssh_digest_update(ctx->ictx, ctx->buf, ctx->buf_len) < 0)
81			return -1;
82		for (i = 0; i < ctx->buf_len; i++)
83			ctx->buf[i] ^= 0x36 ^ 0x5c;
84		if (ssh_digest_update(ctx->octx, ctx->buf, ctx->buf_len) < 0)
85			return -1;
86		explicit_bzero(ctx->buf, ctx->buf_len);
87	}
88	/* start with ictx */
89	if (ssh_digest_copy_state(ctx->ictx, ctx->digest) < 0)
90		return -1;
91	return 0;
92}
93
94int
95ssh_hmac_update(struct ssh_hmac_ctx *ctx, const void *m, size_t mlen)
96{
97	return ssh_digest_update(ctx->digest, m, mlen);
98}
99
100int
101ssh_hmac_update_buffer(struct ssh_hmac_ctx *ctx, const struct sshbuf *b)
102{
103	return ssh_digest_update_buffer(ctx->digest, b);
104}
105
106int
107ssh_hmac_final(struct ssh_hmac_ctx *ctx, u_char *d, size_t dlen)
108{
109	size_t len;
110
111	len = ssh_digest_bytes(ctx->alg);
112	if (dlen < len ||
113	    ssh_digest_final(ctx->digest, ctx->buf, len))
114		return -1;
115	/* switch to octx */
116	if (ssh_digest_copy_state(ctx->octx, ctx->digest) < 0 ||
117	    ssh_digest_update(ctx->digest, ctx->buf, len) < 0 ||
118	    ssh_digest_final(ctx->digest, d, dlen) < 0)
119		return -1;
120	return 0;
121}
122
123void
124ssh_hmac_free(struct ssh_hmac_ctx *ctx)
125{
126	if (ctx != NULL) {
127		ssh_digest_free(ctx->ictx);
128		ssh_digest_free(ctx->octx);
129		ssh_digest_free(ctx->digest);
130		if (ctx->buf) {
131			explicit_bzero(ctx->buf, ctx->buf_len);
132			free(ctx->buf);
133		}
134		freezero(ctx, sizeof(*ctx));
135	}
136}
137
138#ifdef TEST
139
140/* cc -DTEST hmac.c digest.c buffer.c cleanup.c fatal.c log.c xmalloc.c -lcrypto */
141static void
142hmac_test(void *key, size_t klen, void *m, size_t mlen, u_char *e, size_t elen)
143{
144	struct ssh_hmac_ctx	*ctx;
145	size_t			 i;
146	u_char			 digest[16];
147
148	if ((ctx = ssh_hmac_start(SSH_DIGEST_MD5)) == NULL)
149		printf("ssh_hmac_start failed");
150	if (ssh_hmac_init(ctx, key, klen) < 0 ||
151	    ssh_hmac_update(ctx, m, mlen) < 0 ||
152	    ssh_hmac_final(ctx, digest, sizeof(digest)) < 0)
153		printf("ssh_hmac_xxx failed");
154	ssh_hmac_free(ctx);
155
156	if (memcmp(e, digest, elen)) {
157		for (i = 0; i < elen; i++)
158			printf("[%zu] %2.2x %2.2x\n", i, e[i], digest[i]);
159		printf("mismatch\n");
160	} else
161		printf("ok\n");
162}
163
164int
165main(int argc, char **argv)
166{
167	/* try test vectors from RFC 2104 */
168
169	u_char key1[16] = {
170	    0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb,
171	    0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb };
172	u_char *data1 = "Hi There";
173	u_char dig1[16] = {
174	    0x92, 0x94, 0x72, 0x7a, 0x36, 0x38, 0xbb, 0x1c,
175	    0x13, 0xf4, 0x8e, 0xf8, 0x15, 0x8b, 0xfc, 0x9d };
176
177	u_char *key2 = "Jefe";
178	u_char *data2 = "what do ya want for nothing?";
179	u_char dig2[16] = {
180	    0x75, 0x0c, 0x78, 0x3e, 0x6a, 0xb0, 0xb5, 0x03,
181	    0xea, 0xa8, 0x6e, 0x31, 0x0a, 0x5d, 0xb7, 0x38 };
182
183	u_char key3[16];
184	u_char data3[50];
185	u_char dig3[16] = {
186	    0x56, 0xbe, 0x34, 0x52, 0x1d, 0x14, 0x4c, 0x88,
187	    0xdb, 0xb8, 0xc7, 0x33, 0xf0, 0xe8, 0xb3, 0xf6 };
188	memset(key3, 0xaa, sizeof(key3));
189	memset(data3, 0xdd, sizeof(data3));
190
191	hmac_test(key1, sizeof(key1), data1, strlen(data1), dig1, sizeof(dig1));
192	hmac_test(key2, strlen(key2), data2, strlen(data2), dig2, sizeof(dig2));
193	hmac_test(key3, sizeof(key3), data3, sizeof(data3), dig3, sizeof(dig3));
194
195	return 0;
196}
197
198#endif
199