1 /* $OpenBSD: pkcs5_pbkdf2.c,v 1.6 2014/01/31 16:56:32 tedu Exp $ */ 2 3 /*- 4 * Copyright (c) 2008 Damien Bergamini <damien.bergamini@free.fr> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 #include <sys/param.h> 21 22 #include <string.h> 23 #include <limits.h> 24 #include <stdlib.h> 25 #include <util.h> 26 27 #include <sha1.h> 28 29 /* 30 * HMAC-SHA-1 (from RFC 2202). 31 */ 32 static void 33 hmac_sha1(const u_int8_t *text, size_t text_len, const u_int8_t *key, 34 size_t key_len, u_int8_t digest[SHA1_DIGEST_LENGTH]) 35 { 36 SHA1_CTX ctx; 37 u_int8_t k_pad[SHA1_BLOCK_LENGTH]; 38 u_int8_t tk[SHA1_DIGEST_LENGTH]; 39 int i; 40 41 if (key_len > SHA1_BLOCK_LENGTH) { 42 SHA1Init(&ctx); 43 SHA1Update(&ctx, key, key_len); 44 SHA1Final(tk, &ctx); 45 46 key = tk; 47 key_len = SHA1_DIGEST_LENGTH; 48 } 49 50 bzero(k_pad, sizeof k_pad); 51 bcopy(key, k_pad, key_len); 52 for (i = 0; i < SHA1_BLOCK_LENGTH; i++) 53 k_pad[i] ^= 0x36; 54 55 SHA1Init(&ctx); 56 SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH); 57 SHA1Update(&ctx, text, text_len); 58 SHA1Final(digest, &ctx); 59 60 bzero(k_pad, sizeof k_pad); 61 bcopy(key, k_pad, key_len); 62 for (i = 0; i < SHA1_BLOCK_LENGTH; i++) 63 k_pad[i] ^= 0x5c; 64 65 SHA1Init(&ctx); 66 SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH); 67 SHA1Update(&ctx, digest, SHA1_DIGEST_LENGTH); 68 SHA1Final(digest, &ctx); 69 } 70 71 /* 72 * Password-Based Key Derivation Function 2 (PKCS #5 v2.0). 73 * Code based on IEEE Std 802.11-2007, Annex H.4.2. 74 */ 75 int 76 pkcs5_pbkdf2(const char *pass, size_t pass_len, const uint8_t *salt, 77 size_t salt_len, uint8_t *key, size_t key_len, unsigned int rounds) 78 { 79 uint8_t *asalt, obuf[SHA1_DIGEST_LENGTH]; 80 uint8_t d1[SHA1_DIGEST_LENGTH], d2[SHA1_DIGEST_LENGTH]; 81 unsigned int i, j; 82 unsigned int count; 83 size_t r; 84 85 if (rounds < 1 || key_len == 0) 86 return -1; 87 if (salt_len == 0 || salt_len > SIZE_MAX - 4) 88 return -1; 89 if ((asalt = malloc(salt_len + 4)) == NULL) 90 return -1; 91 92 memcpy(asalt, salt, salt_len); 93 94 for (count = 1; key_len > 0; count++) { 95 asalt[salt_len + 0] = (count >> 24) & 0xff; 96 asalt[salt_len + 1] = (count >> 16) & 0xff; 97 asalt[salt_len + 2] = (count >> 8) & 0xff; 98 asalt[salt_len + 3] = count & 0xff; 99 hmac_sha1(asalt, salt_len + 4, pass, pass_len, d1); 100 memcpy(obuf, d1, sizeof(obuf)); 101 102 for (i = 1; i < rounds; i++) { 103 hmac_sha1(d1, sizeof(d1), pass, pass_len, d2); 104 memcpy(d1, d2, sizeof(d1)); 105 for (j = 0; j < sizeof(obuf); j++) 106 obuf[j] ^= d1[j]; 107 } 108 109 r = MIN(key_len, SHA1_DIGEST_LENGTH); 110 memcpy(key, obuf, r); 111 key += r; 112 key_len -= r; 113 }; 114 explicit_bzero(asalt, salt_len + 4); 115 free(asalt); 116 explicit_bzero(d1, sizeof(d1)); 117 explicit_bzero(d2, sizeof(d2)); 118 explicit_bzero(obuf, sizeof(obuf)); 119 120 return 0; 121 } 122