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/digest.h> 56 #include <openssl/hmac.h> 57 #include <openssl/mem.h> 58 59 #include "internal.h" 60 #include "../../internal.h" 61 62 63 // tls1_P_hash computes the TLS P_<hash> function as described in RFC 5246, 64 // section 5. It XORs |out_len| bytes to |out|, using |md| as the hash and 65 // |secret| as the secret. |label|, |seed1|, and |seed2| are concatenated to 66 // form the seed parameter. It returns true on success and false on failure. 67 static int tls1_P_hash(uint8_t *out, size_t out_len, 68 const EVP_MD *md, 69 const uint8_t *secret, size_t secret_len, 70 const char *label, size_t label_len, 71 const uint8_t *seed1, size_t seed1_len, 72 const uint8_t *seed2, size_t seed2_len) { 73 HMAC_CTX ctx, ctx_tmp, ctx_init; 74 uint8_t A1[EVP_MAX_MD_SIZE]; 75 unsigned A1_len; 76 int ret = 0; 77 78 const size_t chunk = EVP_MD_size(md); 79 HMAC_CTX_init(&ctx); 80 HMAC_CTX_init(&ctx_tmp); 81 HMAC_CTX_init(&ctx_init); 82 83 if (!HMAC_Init_ex(&ctx_init, secret, secret_len, md, NULL) || 84 !HMAC_CTX_copy_ex(&ctx, &ctx_init) || 85 !HMAC_Update(&ctx, (const uint8_t *) label, label_len) || 86 !HMAC_Update(&ctx, seed1, seed1_len) || 87 !HMAC_Update(&ctx, seed2, seed2_len) || 88 !HMAC_Final(&ctx, A1, &A1_len)) { 89 goto err; 90 } 91 92 for (;;) { 93 unsigned len; 94 uint8_t hmac[EVP_MAX_MD_SIZE]; 95 if (!HMAC_CTX_copy_ex(&ctx, &ctx_init) || 96 !HMAC_Update(&ctx, A1, A1_len) || 97 // Save a copy of |ctx| to compute the next A1 value below. 98 (out_len > chunk && !HMAC_CTX_copy_ex(&ctx_tmp, &ctx)) || 99 !HMAC_Update(&ctx, (const uint8_t *) label, label_len) || 100 !HMAC_Update(&ctx, seed1, seed1_len) || 101 !HMAC_Update(&ctx, seed2, seed2_len) || 102 !HMAC_Final(&ctx, hmac, &len)) { 103 goto err; 104 } 105 assert(len == chunk); 106 107 // XOR the result into |out|. 108 if (len > out_len) { 109 len = out_len; 110 } 111 for (unsigned i = 0; i < len; i++) { 112 out[i] ^= hmac[i]; 113 } 114 out += len; 115 out_len -= len; 116 117 if (out_len == 0) { 118 break; 119 } 120 121 // Calculate the next A1 value. 122 if (!HMAC_Final(&ctx_tmp, A1, &A1_len)) { 123 goto err; 124 } 125 } 126 127 ret = 1; 128 129 err: 130 OPENSSL_cleanse(A1, sizeof(A1)); 131 HMAC_CTX_cleanup(&ctx); 132 HMAC_CTX_cleanup(&ctx_tmp); 133 HMAC_CTX_cleanup(&ctx_init); 134 return ret; 135 } 136 137 int CRYPTO_tls1_prf(const EVP_MD *digest, 138 uint8_t *out, size_t out_len, 139 const uint8_t *secret, size_t secret_len, 140 const char *label, size_t label_len, 141 const uint8_t *seed1, size_t seed1_len, 142 const uint8_t *seed2, size_t seed2_len) { 143 if (out_len == 0) { 144 return 1; 145 } 146 147 OPENSSL_memset(out, 0, out_len); 148 149 if (digest == EVP_md5_sha1()) { 150 // If using the MD5/SHA1 PRF, |secret| is partitioned between MD5 and SHA-1. 151 size_t secret_half = secret_len - (secret_len / 2); 152 if (!tls1_P_hash(out, out_len, EVP_md5(), secret, secret_half, label, 153 label_len, seed1, seed1_len, seed2, seed2_len)) { 154 return 0; 155 } 156 157 // Note that, if |secret_len| is odd, the two halves share a byte. 158 secret += secret_len - secret_half; 159 secret_len = secret_half; 160 digest = EVP_sha1(); 161 } 162 163 return tls1_P_hash(out, out_len, digest, secret, secret_len, label, label_len, 164 seed1, seed1_len, seed2, seed2_len); 165 } 166
