xref: /openssh-portable/hmac.c (revision df100be5)
1 /* $OpenBSD: hmac.c,v 1.12 2015/03/24 20:03:44 markus 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 #include <string.h>
22 
23 #include "sshbuf.h"
24 #include "digest.h"
25 #include "hmac.h"
26 
27 struct ssh_hmac_ctx {
28 	int			 alg;
29 	struct ssh_digest_ctx	*ictx;
30 	struct ssh_digest_ctx	*octx;
31 	struct ssh_digest_ctx	*digest;
32 	u_char			*buf;
33 	size_t			 buf_len;
34 };
35 
36 size_t
ssh_hmac_bytes(int alg)37 ssh_hmac_bytes(int alg)
38 {
39 	return ssh_digest_bytes(alg);
40 }
41 
42 struct ssh_hmac_ctx *
ssh_hmac_start(int alg)43 ssh_hmac_start(int alg)
44 {
45 	struct ssh_hmac_ctx	*ret;
46 
47 	if ((ret = calloc(1, sizeof(*ret))) == NULL)
48 		return NULL;
49 	ret->alg = alg;
50 	if ((ret->ictx = ssh_digest_start(alg)) == NULL ||
51 	    (ret->octx = ssh_digest_start(alg)) == NULL ||
52 	    (ret->digest = ssh_digest_start(alg)) == NULL)
53 		goto fail;
54 	ret->buf_len = ssh_digest_blocksize(ret->ictx);
55 	if ((ret->buf = calloc(1, ret->buf_len)) == NULL)
56 		goto fail;
57 	return ret;
58 fail:
59 	ssh_hmac_free(ret);
60 	return NULL;
61 }
62 
63 int
ssh_hmac_init(struct ssh_hmac_ctx * ctx,const void * key,size_t klen)64 ssh_hmac_init(struct ssh_hmac_ctx *ctx, const void *key, size_t klen)
65 {
66 	size_t i;
67 
68 	/* reset ictx and octx if no is key given */
69 	if (key != NULL) {
70 		/* truncate long keys */
71 		if (klen <= ctx->buf_len)
72 			memcpy(ctx->buf, key, klen);
73 		else if (ssh_digest_memory(ctx->alg, key, klen, ctx->buf,
74 		    ctx->buf_len) < 0)
75 			return -1;
76 		for (i = 0; i < ctx->buf_len; i++)
77 			ctx->buf[i] ^= 0x36;
78 		if (ssh_digest_update(ctx->ictx, ctx->buf, ctx->buf_len) < 0)
79 			return -1;
80 		for (i = 0; i < ctx->buf_len; i++)
81 			ctx->buf[i] ^= 0x36 ^ 0x5c;
82 		if (ssh_digest_update(ctx->octx, ctx->buf, ctx->buf_len) < 0)
83 			return -1;
84 		explicit_bzero(ctx->buf, ctx->buf_len);
85 	}
86 	/* start with ictx */
87 	if (ssh_digest_copy_state(ctx->ictx, ctx->digest) < 0)
88 		return -1;
89 	return 0;
90 }
91 
92 int
ssh_hmac_update(struct ssh_hmac_ctx * ctx,const void * m,size_t mlen)93 ssh_hmac_update(struct ssh_hmac_ctx *ctx, const void *m, size_t mlen)
94 {
95 	return ssh_digest_update(ctx->digest, m, mlen);
96 }
97 
98 int
ssh_hmac_update_buffer(struct ssh_hmac_ctx * ctx,const struct sshbuf * b)99 ssh_hmac_update_buffer(struct ssh_hmac_ctx *ctx, const struct sshbuf *b)
100 {
101 	return ssh_digest_update_buffer(ctx->digest, b);
102 }
103 
104 int
ssh_hmac_final(struct ssh_hmac_ctx * ctx,u_char * d,size_t dlen)105 ssh_hmac_final(struct ssh_hmac_ctx *ctx, u_char *d, size_t dlen)
106 {
107 	size_t len;
108 
109 	len = ssh_digest_bytes(ctx->alg);
110 	if (dlen < len ||
111 	    ssh_digest_final(ctx->digest, ctx->buf, len))
112 		return -1;
113 	/* switch to octx */
114 	if (ssh_digest_copy_state(ctx->octx, ctx->digest) < 0 ||
115 	    ssh_digest_update(ctx->digest, ctx->buf, len) < 0 ||
116 	    ssh_digest_final(ctx->digest, d, dlen) < 0)
117 		return -1;
118 	return 0;
119 }
120 
121 void
ssh_hmac_free(struct ssh_hmac_ctx * ctx)122 ssh_hmac_free(struct ssh_hmac_ctx *ctx)
123 {
124 	if (ctx != NULL) {
125 		ssh_digest_free(ctx->ictx);
126 		ssh_digest_free(ctx->octx);
127 		ssh_digest_free(ctx->digest);
128 		if (ctx->buf) {
129 			explicit_bzero(ctx->buf, ctx->buf_len);
130 			free(ctx->buf);
131 		}
132 		explicit_bzero(ctx, sizeof(*ctx));
133 		free(ctx);
134 	}
135 }
136 
137 #ifdef TEST
138 
139 /* cc -DTEST hmac.c digest.c buffer.c cleanup.c fatal.c log.c xmalloc.c -lcrypto */
140 static void
hmac_test(void * key,size_t klen,void * m,size_t mlen,u_char * e,size_t elen)141 hmac_test(void *key, size_t klen, void *m, size_t mlen, u_char *e, size_t elen)
142 {
143 	struct ssh_hmac_ctx	*ctx;
144 	size_t			 i;
145 	u_char			 digest[16];
146 
147 	if ((ctx = ssh_hmac_start(SSH_DIGEST_MD5)) == NULL)
148 		printf("ssh_hmac_start failed");
149 	if (ssh_hmac_init(ctx, key, klen) < 0 ||
150 	    ssh_hmac_update(ctx, m, mlen) < 0 ||
151 	    ssh_hmac_final(ctx, digest, sizeof(digest)) < 0)
152 		printf("ssh_hmac_xxx failed");
153 	ssh_hmac_free(ctx);
154 
155 	if (memcmp(e, digest, elen)) {
156 		for (i = 0; i < elen; i++)
157 			printf("[%zu] %2.2x %2.2x\n", i, e[i], digest[i]);
158 		printf("mismatch\n");
159 	} else
160 		printf("ok\n");
161 }
162 
163 int
main(int argc,char ** argv)164 main(int argc, char **argv)
165 {
166 	/* try test vectors from RFC 2104 */
167 
168 	u_char key1[16] = {
169 	    0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb,
170 	    0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb, 0xb };
171 	u_char *data1 = "Hi There";
172 	u_char dig1[16] = {
173 	    0x92, 0x94, 0x72, 0x7a, 0x36, 0x38, 0xbb, 0x1c,
174 	    0x13, 0xf4, 0x8e, 0xf8, 0x15, 0x8b, 0xfc, 0x9d };
175 
176 	u_char *key2 = "Jefe";
177 	u_char *data2 = "what do ya want for nothing?";
178 	u_char dig2[16] = {
179 	    0x75, 0x0c, 0x78, 0x3e, 0x6a, 0xb0, 0xb5, 0x03,
180 	    0xea, 0xa8, 0x6e, 0x31, 0x0a, 0x5d, 0xb7, 0x38 };
181 
182 	u_char key3[16];
183 	u_char data3[50];
184 	u_char dig3[16] = {
185 	    0x56, 0xbe, 0x34, 0x52, 0x1d, 0x14, 0x4c, 0x88,
186 	    0xdb, 0xb8, 0xc7, 0x33, 0xf0, 0xe8, 0xb3, 0xf6 };
187 	memset(key3, 0xaa, sizeof(key3));
188 	memset(data3, 0xdd, sizeof(data3));
189 
190 	hmac_test(key1, sizeof(key1), data1, strlen(data1), dig1, sizeof(dig1));
191 	hmac_test(key2, strlen(key2), data2, strlen(data2), dig2, sizeof(dig2));
192 	hmac_test(key3, sizeof(key3), data3, sizeof(data3), dig3, sizeof(dig3));
193 
194 	return 0;
195 }
196 
197 #endif
198