1 /* ==================================================================== 2 * Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in 13 * the documentation and/or other materials provided with the 14 * distribution. 15 * 16 * 3. All advertising materials mentioning features or use of this 17 * software must display the following acknowledgment: 18 * "This product includes software developed by the OpenSSL Project 19 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 20 * 21 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 22 * endorse or promote products derived from this software without 23 * prior written permission. For written permission, please contact 24 * openssl-core (at) openssl.org. 25 * 26 * 5. Products derived from this software may not be called "OpenSSL" 27 * nor may "OpenSSL" appear in their names without prior written 28 * permission of the OpenSSL Project. 29 * 30 * 6. Redistributions of any form whatsoever must retain the following 31 * acknowledgment: 32 * "This product includes software developed by the OpenSSL Project 33 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 34 * 35 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 36 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 37 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 38 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 39 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 40 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 41 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 42 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 43 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 44 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 45 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 46 * OF THE POSSIBILITY OF SUCH DAMAGE. 47 * ==================================================================== 48 * 49 * This product includes cryptographic software written by Eric Young 50 * (eay (at) cryptsoft.com). This product includes software written by Tim 51 * Hudson (tjh (at) cryptsoft.com). */ 52 53 #include <assert.h> 54 55 #include <openssl/hmac.h> 56 #include <openssl/mem.h> 57 58 #include "internal.h" 59 #include "../crypto/internal.h" 60 61 62 // tls1_P_hash computes the TLS P_<hash> function as described in RFC 5246, 63 // section 5. It XORs |out_len| bytes to |out|, using |md| as the hash and 64 // |secret| as the secret. |label|, |seed1|, and |seed2| are concatenated to 65 // form the seed parameter. It returns true on success and false on failure. 66 static int tls1_P_hash(uint8_t *out, size_t out_len, 67 const EVP_MD *md, 68 const uint8_t *secret, size_t secret_len, 69 const char *label, size_t label_len, 70 const uint8_t *seed1, size_t seed1_len, 71 const uint8_t *seed2, size_t seed2_len) { 72 HMAC_CTX ctx, ctx_tmp, ctx_init; 73 uint8_t A1[EVP_MAX_MD_SIZE]; 74 unsigned A1_len; 75 int ret = 0; 76 77 const size_t chunk = EVP_MD_size(md); 78 HMAC_CTX_init(&ctx); 79 HMAC_CTX_init(&ctx_tmp); 80 HMAC_CTX_init(&ctx_init); 81 82 if (!HMAC_Init_ex(&ctx_init, secret, secret_len, md, NULL) || 83 !HMAC_CTX_copy_ex(&ctx, &ctx_init) || 84 !HMAC_Update(&ctx, (const uint8_t *) label, label_len) || 85 !HMAC_Update(&ctx, seed1, seed1_len) || 86 !HMAC_Update(&ctx, seed2, seed2_len) || 87 !HMAC_Final(&ctx, A1, &A1_len)) { 88 goto err; 89 } 90 91 for (;;) { 92 unsigned len; 93 uint8_t hmac[EVP_MAX_MD_SIZE]; 94 if (!HMAC_CTX_copy_ex(&ctx, &ctx_init) || 95 !HMAC_Update(&ctx, A1, A1_len) || 96 // Save a copy of |ctx| to compute the next A1 value below. 97 (out_len > chunk && !HMAC_CTX_copy_ex(&ctx_tmp, &ctx)) || 98 !HMAC_Update(&ctx, (const uint8_t *) label, label_len) || 99 !HMAC_Update(&ctx, seed1, seed1_len) || 100 !HMAC_Update(&ctx, seed2, seed2_len) || 101 !HMAC_Final(&ctx, hmac, &len)) { 102 goto err; 103 } 104 assert(len == chunk); 105 106 // XOR the result into |out|. 107 if (len > out_len) { 108 len = out_len; 109 } 110 for (unsigned i = 0; i < len; i++) { 111 out[i] ^= hmac[i]; 112 } 113 out += len; 114 out_len -= len; 115 116 if (out_len == 0) { 117 break; 118 } 119 120 // Calculate the next A1 value. 121 if (!HMAC_Final(&ctx_tmp, A1, &A1_len)) { 122 goto err; 123 } 124 } 125 126 ret = 1; 127 128 err: 129 OPENSSL_cleanse(A1, sizeof(A1)); 130 HMAC_CTX_cleanup(&ctx); 131 HMAC_CTX_cleanup(&ctx_tmp); 132 HMAC_CTX_cleanup(&ctx_init); 133 return ret; 134 } 135 136 int CRYPTO_tls1_prf(const EVP_MD *digest, 137 uint8_t *out, size_t out_len, 138 const uint8_t *secret, size_t secret_len, 139 const char *label, size_t label_len, 140 const uint8_t *seed1, size_t seed1_len, 141 const uint8_t *seed2, size_t seed2_len) { 142 if (out_len == 0) { 143 return 1; 144 } 145 146 OPENSSL_memset(out, 0, out_len); 147 148 if (digest == EVP_md5_sha1()) { 149 // If using the MD5/SHA1 PRF, |secret| is partitioned between MD5 and SHA-1. 150 size_t secret_half = secret_len - (secret_len / 2); 151 if (!tls1_P_hash(out, out_len, EVP_md5(), secret, secret_half, label, 152 label_len, seed1, seed1_len, seed2, seed2_len)) { 153 return 0; 154 } 155 156 // Note that, if |secret_len| is odd, the two halves share a byte. 157 secret += secret_len - secret_half; 158 secret_len = secret_half; 159 digest = EVP_sha1(); 160 } 161 162 return tls1_P_hash(out, out_len, digest, secret, secret_len, label, label_len, 163 seed1, seed1_len, seed2, seed2_len); 164 } 165
