xref: /openssh-portable/hmac.c (revision d5ba1c03)
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 
29 struct 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 
38 size_t
ssh_hmac_bytes(int alg)39 ssh_hmac_bytes(int alg)
40 {
41 	return ssh_digest_bytes(alg);
42 }
43 
44 struct ssh_hmac_ctx *
ssh_hmac_start(int alg)45 ssh_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;
60 fail:
61 	ssh_hmac_free(ret);
62 	return NULL;
63 }
64 
65 int
ssh_hmac_init(struct ssh_hmac_ctx * ctx,const void * key,size_t klen)66 ssh_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 
94 int
ssh_hmac_update(struct ssh_hmac_ctx * ctx,const void * m,size_t mlen)95 ssh_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 
100 int
ssh_hmac_update_buffer(struct ssh_hmac_ctx * ctx,const struct sshbuf * b)101 ssh_hmac_update_buffer(struct ssh_hmac_ctx *ctx, const struct sshbuf *b)
102 {
103 	return ssh_digest_update_buffer(ctx->digest, b);
104 }
105 
106 int
ssh_hmac_final(struct ssh_hmac_ctx * ctx,u_char * d,size_t dlen)107 ssh_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 
123 void
ssh_hmac_free(struct ssh_hmac_ctx * ctx)124 ssh_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 */
141 static void
hmac_test(void * key,size_t klen,void * m,size_t mlen,u_char * e,size_t elen)142 hmac_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 
164 int
main(int argc,char ** argv)165 main(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