2 * Written by Stephen Henson for the OpenSSL project.
4 /* ====================================================================
5 * Copyright (c) 2013 The OpenSSL Project. All rights reserved.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
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
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/)"
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.
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.
33 * 6. Redistributions of any form whatsoever must retain the following
35 * "This product includes software developed by the OpenSSL Project
36 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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 * ====================================================================
54 #include <openssl/ec.h>
55 #include <openssl/evp.h>
57 /* Key derivation function from X9.62/SECG */
58 /* Way more than we will ever need */
59 #define ECDH_KDF_MAX (1 << 30)
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,
66 EVP_MD_CTX *mctx = NULL;
71 if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX
72 || Zlen > ECDH_KDF_MAX)
74 mctx = EVP_MD_CTX_new();
77 mdlen = EVP_MD_size(md);
79 unsigned char mtmp[EVP_MAX_MD_SIZE];
80 EVP_DigestInit_ex(mctx, md, NULL);
82 ctr[2] = (i >> 8) & 0xFF;
83 ctr[1] = (i >> 16) & 0xFF;
84 ctr[0] = (i >> 24) & 0xFF;
85 if (!EVP_DigestUpdate(mctx, Z, Zlen))
87 if (!EVP_DigestUpdate(mctx, ctr, sizeof(ctr)))
89 if (!EVP_DigestUpdate(mctx, sinfo, sinfolen))
91 if (outlen >= mdlen) {
92 if (!EVP_DigestFinal(mctx, out, NULL))
99 if (!EVP_DigestFinal(mctx, mtmp, NULL))
101 memcpy(out, mtmp, outlen);
102 OPENSSL_cleanse(mtmp, mdlen);
108 EVP_MD_CTX_free(mctx);