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110 lines
4.1 KiB
C
110 lines
4.1 KiB
C
/* crypto/ecdh/ec_kdf.c */
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/*
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* Written by Stephen Henson for the OpenSSL project.
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*/
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/* ====================================================================
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* Copyright (c) 2013 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*/
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#include <string.h>
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#include <openssl/ecdh.h>
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#include <openssl/evp.h>
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/* Key derivation function from X9.62/SECG */
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/* Way more than we will ever need */
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#define ECDH_KDF_MAX (1 << 30)
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int ECDH_KDF_X9_62(unsigned char *out, size_t outlen,
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const unsigned char *Z, size_t Zlen,
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const unsigned char *sinfo, size_t sinfolen,
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const EVP_MD *md)
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{
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EVP_MD_CTX mctx;
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int rv = 0;
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unsigned int i;
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size_t mdlen;
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unsigned char ctr[4];
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if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX
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|| Zlen > ECDH_KDF_MAX)
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return 0;
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mdlen = EVP_MD_size(md);
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EVP_MD_CTX_init(&mctx);
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for (i = 1;; i++) {
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unsigned char mtmp[EVP_MAX_MD_SIZE];
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EVP_DigestInit_ex(&mctx, md, NULL);
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ctr[3] = i & 0xFF;
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ctr[2] = (i >> 8) & 0xFF;
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ctr[1] = (i >> 16) & 0xFF;
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ctr[0] = (i >> 24) & 0xFF;
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if (!EVP_DigestUpdate(&mctx, Z, Zlen))
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goto err;
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if (!EVP_DigestUpdate(&mctx, ctr, sizeof(ctr)))
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goto err;
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if (!EVP_DigestUpdate(&mctx, sinfo, sinfolen))
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goto err;
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if (outlen >= mdlen) {
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if (!EVP_DigestFinal(&mctx, out, NULL))
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goto err;
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outlen -= mdlen;
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if (outlen == 0)
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break;
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out += mdlen;
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} else {
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if (!EVP_DigestFinal(&mctx, mtmp, NULL))
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goto err;
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memcpy(out, mtmp, outlen);
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OPENSSL_cleanse(mtmp, mdlen);
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break;
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}
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}
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rv = 1;
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err:
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EVP_MD_CTX_cleanup(&mctx);
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return rv;
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}
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