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