1 /* crypto/ecdh/ec_kdf.c */
3 * Written by Stephen Henson for the OpenSSL project.
5 /* ====================================================================
6 * Copyright (c) 2013 The OpenSSL Project. All rights reserved.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * openssl-core@openssl.org.
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
34 * 6. Redistributions of any form whatsoever must retain the following
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
55 #include <openssl/ecdh.h>
56 #include <openssl/evp.h>
58 /* Key derivation function from X9.62/SECG */
59 /* Way more than we will ever need */
60 #define ECDH_KDF_MAX (1 << 30)
62 int ECDH_KDF_X9_62(unsigned char *out, size_t outlen,
63 const unsigned char *Z, size_t Zlen,
64 const unsigned char *sinfo, size_t sinfolen,
72 if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX
73 || Zlen > ECDH_KDF_MAX)
75 mdlen = EVP_MD_size(md);
76 EVP_MD_CTX_init(&mctx);
78 unsigned char mtmp[EVP_MAX_MD_SIZE];
79 EVP_DigestInit_ex(&mctx, md, NULL);
81 ctr[2] = (i >> 8) & 0xFF;
82 ctr[1] = (i >> 16) & 0xFF;
83 ctr[0] = (i >> 24) & 0xFF;
84 if (!EVP_DigestUpdate(&mctx, Z, Zlen))
86 if (!EVP_DigestUpdate(&mctx, ctr, sizeof(ctr)))
88 if (!EVP_DigestUpdate(&mctx, sinfo, sinfolen))
90 if (outlen >= mdlen) {
91 if (!EVP_DigestFinal(&mctx, out, NULL))
98 if (!EVP_DigestFinal(&mctx, mtmp, NULL))
100 memcpy(out, mtmp, outlen);
101 OPENSSL_cleanse(mtmp, mdlen);
107 EVP_MD_CTX_cleanup(&mctx);