1 /* $OpenBSD: pkcs5_pbkdf2.c,v 1.9 2015/02/05 12:59:57 millert 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 21 #include <string.h> 22 #include <stdint.h> 23 #include <stdlib.h> 24 #include <util.h> 25 26 #include <sha1.h> 27 28 #define MINIMUM(a,b) (((a) < (b)) ? (a) : (b)) 29 30 /* 31 * HMAC-SHA-1 (from RFC 2202). 32 */ 33 static void 34 hmac_sha1(const u_int8_t *text, size_t text_len, const u_int8_t *key, 35 size_t key_len, u_int8_t digest[SHA1_DIGEST_LENGTH]) 36 { 37 SHA1_CTX ctx; 38 u_int8_t k_pad[SHA1_BLOCK_LENGTH]; 39 u_int8_t tk[SHA1_DIGEST_LENGTH]; 40 int i; 41 42 if (key_len > SHA1_BLOCK_LENGTH) { 43 SHA1Init(&ctx); 44 SHA1Update(&ctx, key, key_len); 45 SHA1Final(tk, &ctx); 46 47 key = tk; 48 key_len = SHA1_DIGEST_LENGTH; 49 } 50 51 bzero(k_pad, sizeof k_pad); 52 bcopy(key, k_pad, key_len); 53 for (i = 0; i < SHA1_BLOCK_LENGTH; i++) 54 k_pad[i] ^= 0x36; 55 56 SHA1Init(&ctx); 57 SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH); 58 SHA1Update(&ctx, text, text_len); 59 SHA1Final(digest, &ctx); 60 61 bzero(k_pad, sizeof k_pad); 62 bcopy(key, k_pad, key_len); 63 for (i = 0; i < SHA1_BLOCK_LENGTH; i++) 64 k_pad[i] ^= 0x5c; 65 66 SHA1Init(&ctx); 67 SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH); 68 SHA1Update(&ctx, digest, SHA1_DIGEST_LENGTH); 69 SHA1Final(digest, &ctx); 70 } 71 72 /* 73 * Password-Based Key Derivation Function 2 (PKCS #5 v2.0). 74 * Code based on IEEE Std 802.11-2007, Annex H.4.2. 75 */ 76 int 77 pkcs5_pbkdf2(const char *pass, size_t pass_len, const uint8_t *salt, 78 size_t salt_len, uint8_t *key, size_t key_len, unsigned int rounds) 79 { 80 uint8_t *asalt, obuf[SHA1_DIGEST_LENGTH]; 81 uint8_t d1[SHA1_DIGEST_LENGTH], d2[SHA1_DIGEST_LENGTH]; 82 unsigned int i, j; 83 unsigned int count; 84 size_t r; 85 86 if (rounds < 1 || key_len == 0) 87 return -1; 88 if (salt_len == 0 || salt_len > SIZE_MAX - 4) 89 return -1; 90 if ((asalt = malloc(salt_len + 4)) == NULL) 91 return -1; 92 93 memcpy(asalt, salt, salt_len); 94 95 for (count = 1; key_len > 0; count++) { 96 asalt[salt_len + 0] = (count >> 24) & 0xff; 97 asalt[salt_len + 1] = (count >> 16) & 0xff; 98 asalt[salt_len + 2] = (count >> 8) & 0xff; 99 asalt[salt_len + 3] = count & 0xff; 100 hmac_sha1(asalt, salt_len + 4, pass, pass_len, d1); 101 memcpy(obuf, d1, sizeof(obuf)); 102 103 for (i = 1; i < rounds; i++) { 104 hmac_sha1(d1, sizeof(d1), pass, pass_len, d2); 105 memcpy(d1, d2, sizeof(d1)); 106 for (j = 0; j < sizeof(obuf); j++) 107 obuf[j] ^= d1[j]; 108 } 109 110 r = MINIMUM(key_len, SHA1_DIGEST_LENGTH); 111 memcpy(key, obuf, r); 112 key += r; 113 key_len -= r; 114 }; 115 explicit_bzero(asalt, salt_len + 4); 116 free(asalt); 117 explicit_bzero(d1, sizeof(d1)); 118 explicit_bzero(d2, sizeof(d2)); 119 explicit_bzero(obuf, sizeof(obuf)); 120 121 return 0; 122 } 123