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@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@cryptsoft.com). This product includes software written by Tim
51 * Hudson (tjh@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.
67static 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
129err:
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
137int 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