crypto/openssh/hmac.c

   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
  39 ssh_hmac_bytes(int alg)
  40 {
  41         return ssh_digest_bytes(alg);
  42 }
  43
  44 struct ssh_hmac_ctx *
  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
  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
  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
 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
 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
 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
 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
 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