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 199