| /* ==================================================================== |
| * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. |
| * |
| * The Elliptic Curve Public-Key Crypto Library (ECC Code) included |
| * herein is developed by SUN MICROSYSTEMS, INC., and is contributed |
| * to the OpenSSL project. |
| * |
| * The ECC Code is licensed pursuant to the OpenSSL open source |
| * license provided below. |
| * |
| * The ECDH software is originally written by Douglas Stebila of |
| * Sun Microsystems Laboratories. |
| * |
| */ |
| /* ==================================================================== |
| * Copyright (c) 2000-2002 The OpenSSL Project. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. All advertising materials mentioning features or use of this |
| * software must display the following acknowledgment: |
| * "This product includes software developed by the OpenSSL Project |
| * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" |
| * |
| * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to |
| * endorse or promote products derived from this software without |
| * prior written permission. For written permission, please contact |
| * licensing@OpenSSL.org. |
| * |
| * 5. Products derived from this software may not be called "OpenSSL" |
| * nor may "OpenSSL" appear in their names without prior written |
| * permission of the OpenSSL Project. |
| * |
| * 6. Redistributions of any form whatsoever must retain the following |
| * acknowledgment: |
| * "This product includes software developed by the OpenSSL Project |
| * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY |
| * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| * OF THE POSSIBILITY OF SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This product includes cryptographic software written by Eric Young |
| * (eay@cryptsoft.com). This product includes software written by Tim |
| * Hudson (tjh@cryptsoft.com). */ |
| |
| #include <openssl/ecdh.h> |
| |
| #include <openssl/bn.h> |
| #include <openssl/digest.h> |
| #include <openssl/err.h> |
| #include <openssl/mem.h> |
| |
| |
| int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, |
| EC_KEY *priv_key, void *(*KDF)(const void *in, size_t inlen, |
| void *out, size_t *outlen)) { |
| BN_CTX *ctx; |
| EC_POINT *tmp = NULL; |
| BIGNUM *x = NULL, *y = NULL; |
| const BIGNUM *priv; |
| const EC_GROUP *group; |
| int ret = -1; |
| size_t buflen, len; |
| uint8_t *buf = NULL; |
| |
| if ((ctx = BN_CTX_new()) == NULL) { |
| goto err; |
| } |
| BN_CTX_start(ctx); |
| x = BN_CTX_get(ctx); |
| y = BN_CTX_get(ctx); |
| |
| priv = EC_KEY_get0_private_key(priv_key); |
| if (priv == NULL) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ECDH_R_NO_PRIVATE_VALUE); |
| goto err; |
| } |
| |
| group = EC_KEY_get0_group(priv_key); |
| |
| tmp = EC_POINT_new(group); |
| if (tmp == NULL) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv, ctx)) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ECDH_R_POINT_ARITHMETIC_FAILURE); |
| goto err; |
| } |
| |
| if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ECDH_R_POINT_ARITHMETIC_FAILURE); |
| goto err; |
| } |
| |
| buflen = (EC_GROUP_get_degree(group) + 7) / 8; |
| len = BN_num_bytes(x); |
| if (len > buflen) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| buf = OPENSSL_malloc(buflen); |
| if (buf == NULL) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| |
| memset(buf, 0, buflen - len); |
| if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ERR_R_BN_LIB); |
| goto err; |
| } |
| |
| if (KDF != 0) { |
| if (KDF(buf, buflen, out, &outlen) == NULL) { |
| OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ECDH_R_KDF_FAILED); |
| goto err; |
| } |
| ret = outlen; |
| } else { |
| /* no KDF, just copy as much as we can */ |
| if (outlen > buflen) { |
| outlen = buflen; |
| } |
| memcpy(out, buf, outlen); |
| ret = outlen; |
| } |
| |
| err: |
| if (tmp) |
| EC_POINT_free(tmp); |
| if (ctx) |
| BN_CTX_end(ctx); |
| if (ctx) |
| BN_CTX_free(ctx); |
| if (buf) |
| OPENSSL_free(buf); |
| return ret; |
| } |
| |
| /* Key derivation function from X9.62/SECG */ |
| /* Way more than we will ever need */ |
| #define ECDH_KDF_MAX (1 << 30) |
| |
| int ECDH_KDF_X9_62(uint8_t *out, size_t outlen, const uint8_t *Z, |
| size_t Zlen, const uint8_t *sinfo, size_t sinfolen, |
| const EVP_MD *md) { |
| EVP_MD_CTX mctx; |
| int rv = 0; |
| unsigned int i; |
| size_t mdlen; |
| uint8_t ctr[4]; |
| |
| if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX || Zlen > ECDH_KDF_MAX) { |
| return 0; |
| } |
| mdlen = EVP_MD_size(md); |
| EVP_MD_CTX_init(&mctx); |
| |
| for (i = 1;; i++) { |
| uint8_t mtmp[EVP_MAX_MD_SIZE]; |
| EVP_DigestInit_ex(&mctx, md, NULL); |
| ctr[3] = i & 0xFF; |
| ctr[2] = (i >> 8) & 0xFF; |
| ctr[1] = (i >> 16) & 0xFF; |
| ctr[0] = (i >> 24) & 0xFF; |
| if (!EVP_DigestUpdate(&mctx, Z, Zlen) || |
| !EVP_DigestUpdate(&mctx, ctr, sizeof(ctr)) || |
| !EVP_DigestUpdate(&mctx, sinfo, sinfolen)) { |
| goto err; |
| } |
| |
| if (outlen >= mdlen) { |
| if (!EVP_DigestFinal(&mctx, out, NULL)) { |
| goto err; |
| } |
| outlen -= mdlen; |
| if (outlen == 0) { |
| break; |
| } |
| out += mdlen; |
| } else { |
| if (!EVP_DigestFinal(&mctx, mtmp, NULL)) { |
| goto err; |
| } |
| memcpy(out, mtmp, outlen); |
| OPENSSL_cleanse(mtmp, mdlen); |
| break; |
| } |
| } |
| rv = 1; |
| |
| err: |
| EVP_MD_CTX_cleanup(&mctx); |
| return rv; |
| } |