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25af7a5d DSH |
1 | /* |
2 | * Written by Stephen Henson for the OpenSSL project. | |
3 | */ | |
4 | /* ==================================================================== | |
5 | * Copyright (c) 2013 The OpenSSL Project. All rights reserved. | |
6 | * | |
7 | * Redistribution and use in source and binary forms, with or without | |
8 | * modification, are permitted provided that the following conditions | |
9 | * are met: | |
10 | * | |
11 | * 1. Redistributions of source code must retain the above copyright | |
0f113f3e | 12 | * notice, this list of conditions and the following disclaimer. |
25af7a5d DSH |
13 | * |
14 | * 2. Redistributions in binary form must reproduce the above copyright | |
15 | * notice, this list of conditions and the following disclaimer in | |
16 | * the documentation and/or other materials provided with the | |
17 | * distribution. | |
18 | * | |
19 | * 3. All advertising materials mentioning features or use of this | |
20 | * software must display the following acknowledgment: | |
21 | * "This product includes software developed by the OpenSSL Project | |
22 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
23 | * | |
24 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
25 | * endorse or promote products derived from this software without | |
26 | * prior written permission. For written permission, please contact | |
27 | * openssl-core@openssl.org. | |
28 | * | |
29 | * 5. Products derived from this software may not be called "OpenSSL" | |
30 | * nor may "OpenSSL" appear in their names without prior written | |
31 | * permission of the OpenSSL Project. | |
32 | * | |
33 | * 6. Redistributions of any form whatsoever must retain the following | |
34 | * acknowledgment: | |
35 | * "This product includes software developed by the OpenSSL Project | |
36 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
37 | * | |
38 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
39 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
40 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
41 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
42 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
43 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
44 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
45 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
46 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
47 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
48 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
49 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
50 | * ==================================================================== | |
51 | */ | |
52 | ||
25af7a5d | 53 | #include <string.h> |
768c53e1 | 54 | #include <openssl/ec.h> |
25af7a5d DSH |
55 | #include <openssl/evp.h> |
56 | ||
25af7a5d | 57 | /* Key derivation function from X9.62/SECG */ |
579a7590 | 58 | /* Way more than we will ever need */ |
0f113f3e | 59 | #define ECDH_KDF_MAX (1 << 30) |
25af7a5d | 60 | |
0f113f3e MC |
61 | int ECDH_KDF_X9_62(unsigned char *out, size_t outlen, |
62 | const unsigned char *Z, size_t Zlen, | |
63 | const unsigned char *sinfo, size_t sinfolen, | |
64 | const EVP_MD *md) | |
65 | { | |
6e59a892 | 66 | EVP_MD_CTX *mctx = NULL; |
0f113f3e MC |
67 | int rv = 0; |
68 | unsigned int i; | |
69 | size_t mdlen; | |
70 | unsigned char ctr[4]; | |
71 | if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX | |
72 | || Zlen > ECDH_KDF_MAX) | |
73 | return 0; | |
bfb0641f | 74 | mctx = EVP_MD_CTX_new(); |
6e59a892 RL |
75 | if (mctx == NULL) |
76 | return 0; | |
0f113f3e | 77 | mdlen = EVP_MD_size(md); |
0f113f3e MC |
78 | for (i = 1;; i++) { |
79 | unsigned char mtmp[EVP_MAX_MD_SIZE]; | |
6e59a892 | 80 | EVP_DigestInit_ex(mctx, md, NULL); |
0f113f3e MC |
81 | ctr[3] = i & 0xFF; |
82 | ctr[2] = (i >> 8) & 0xFF; | |
83 | ctr[1] = (i >> 16) & 0xFF; | |
84 | ctr[0] = (i >> 24) & 0xFF; | |
6e59a892 | 85 | if (!EVP_DigestUpdate(mctx, Z, Zlen)) |
0f113f3e | 86 | goto err; |
6e59a892 | 87 | if (!EVP_DigestUpdate(mctx, ctr, sizeof(ctr))) |
0f113f3e | 88 | goto err; |
6e59a892 | 89 | if (!EVP_DigestUpdate(mctx, sinfo, sinfolen)) |
0f113f3e MC |
90 | goto err; |
91 | if (outlen >= mdlen) { | |
6e59a892 | 92 | if (!EVP_DigestFinal(mctx, out, NULL)) |
0f113f3e MC |
93 | goto err; |
94 | outlen -= mdlen; | |
95 | if (outlen == 0) | |
96 | break; | |
97 | out += mdlen; | |
98 | } else { | |
6e59a892 | 99 | if (!EVP_DigestFinal(mctx, mtmp, NULL)) |
0f113f3e MC |
100 | goto err; |
101 | memcpy(out, mtmp, outlen); | |
102 | OPENSSL_cleanse(mtmp, mdlen); | |
103 | break; | |
104 | } | |
105 | } | |
106 | rv = 1; | |
107 | err: | |
bfb0641f | 108 | EVP_MD_CTX_free(mctx); |
0f113f3e MC |
109 | return rv; |
110 | } |