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 #include "includes.h"
18 __RCSID("$NetBSD: hmac.c,v 1.8 2020/05/28 17:05:49 christos Exp $");
19
20 #include <sys/types.h>
21 #include <string.h>
22 #include <stdlib.h>
23
24 #include "sshbuf.h"
25 #include "digest.h"
26 #include "hmac.h"
27
28 struct ssh_hmac_ctx {
29 int alg;
30 struct ssh_digest_ctx *ictx;
31 struct ssh_digest_ctx *octx;
32 struct ssh_digest_ctx *digest;
33 u_char *buf;
34 size_t buf_len;
35 };
36
37 size_t
ssh_hmac_bytes(int alg)38 ssh_hmac_bytes(int alg)
39 {
40 return ssh_digest_bytes(alg);
41 }
42
43 struct ssh_hmac_ctx *
ssh_hmac_start(int alg)44 ssh_hmac_start(int alg)
45 {
46 struct ssh_hmac_ctx *ret;
47
48 if ((ret = calloc(1, sizeof(*ret))) == NULL)
49 return NULL;
50 ret->alg = alg;
51 if ((ret->ictx = ssh_digest_start(alg)) == NULL ||
52 (ret->octx = ssh_digest_start(alg)) == NULL ||
53 (ret->digest = ssh_digest_start(alg)) == NULL)
54 goto fail;
55 ret->buf_len = ssh_digest_blocksize(ret->ictx);
56 if ((ret->buf = calloc(1, ret->buf_len)) == NULL)
57 goto fail;
58 return ret;
59 fail:
60 ssh_hmac_free(ret);
61 return NULL;
62 }
63
64 int
ssh_hmac_init(struct ssh_hmac_ctx * ctx,const void * key,size_t klen)65 ssh_hmac_init(struct ssh_hmac_ctx *ctx, const void *key, size_t klen)
66 {
67 size_t i;
68
69 /* reset ictx and octx if no is key given */
70 if (key != NULL) {
71 /* truncate long keys */
72 if (klen <= ctx->buf_len)
73 memcpy(ctx->buf, key, klen);
74 else if (ssh_digest_memory(ctx->alg, key, klen, ctx->buf,
75 ctx->buf_len) < 0)
76 return -1;
77 for (i = 0; i < ctx->buf_len; i++)
78 ctx->buf[i] ^= 0x36;
79 if (ssh_digest_update(ctx->ictx, ctx->buf, ctx->buf_len) < 0)
80 return -1;
81 for (i = 0; i < ctx->buf_len; i++)
82 ctx->buf[i] ^= 0x36 ^ 0x5c;
83 if (ssh_digest_update(ctx->octx, ctx->buf, ctx->buf_len) < 0)
84 return -1;
85 explicit_bzero(ctx->buf, ctx->buf_len);
86 }
87 /* start with ictx */
88 if (ssh_digest_copy_state(ctx->ictx, ctx->digest) < 0)
89 return -1;
90 return 0;
91 }
92
93 int
ssh_hmac_update(struct ssh_hmac_ctx * ctx,const void * m,size_t mlen)94 ssh_hmac_update(struct ssh_hmac_ctx *ctx, const void *m, size_t mlen)
95 {
96 return ssh_digest_update(ctx->digest, m, mlen);
97 }
98
99 int
ssh_hmac_update_buffer(struct ssh_hmac_ctx * ctx,const struct sshbuf * b)100 ssh_hmac_update_buffer(struct ssh_hmac_ctx *ctx, const struct sshbuf *b)
101 {
102 return ssh_digest_update_buffer(ctx->digest, b);
103 }
104
105 int
ssh_hmac_final(struct ssh_hmac_ctx * ctx,u_char * d,size_t dlen)106 ssh_hmac_final(struct ssh_hmac_ctx *ctx, u_char *d, size_t dlen)
107 {
108 size_t len;
109
110 len = ssh_digest_bytes(ctx->alg);
111 if (dlen < len ||
112 ssh_digest_final(ctx->digest, ctx->buf, len))
113 return -1;
114 /* switch to octx */
115 if (ssh_digest_copy_state(ctx->octx, ctx->digest) < 0 ||
116 ssh_digest_update(ctx->digest, ctx->buf, len) < 0 ||
117 ssh_digest_final(ctx->digest, d, dlen) < 0)
118 return -1;
119 return 0;
120 }
121
122 void
ssh_hmac_free(struct ssh_hmac_ctx * ctx)123 ssh_hmac_free(struct ssh_hmac_ctx *ctx)
124 {
125 if (ctx != NULL) {
126 ssh_digest_free(ctx->ictx);
127 ssh_digest_free(ctx->octx);
128 ssh_digest_free(ctx->digest);
129 if (ctx->buf) {
130 explicit_bzero(ctx->buf, ctx->buf_len);
131 free(ctx->buf);
132 }
133 freezero(ctx, sizeof(*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