Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 1 | /* crypto/ecdh/ech_ossl.c */ |
| 2 | /* ==================================================================== |
| 3 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. |
| 4 | * |
| 5 | * The Elliptic Curve Public-Key Crypto Library (ECC Code) included |
| 6 | * herein is developed by SUN MICROSYSTEMS, INC., and is contributed |
| 7 | * to the OpenSSL project. |
| 8 | * |
| 9 | * The ECC Code is licensed pursuant to the OpenSSL open source |
| 10 | * license provided below. |
| 11 | * |
| 12 | * The ECDH software is originally written by Douglas Stebila of |
| 13 | * Sun Microsystems Laboratories. |
| 14 | * |
| 15 | */ |
| 16 | /* ==================================================================== |
| 17 | * Copyright (c) 1998-2003 The OpenSSL Project. All rights reserved. |
| 18 | * |
| 19 | * Redistribution and use in source and binary forms, with or without |
| 20 | * modification, are permitted provided that the following conditions |
| 21 | * are met: |
| 22 | * |
| 23 | * 1. Redistributions of source code must retain the above copyright |
| 24 | * notice, this list of conditions and the following disclaimer. |
| 25 | * |
| 26 | * 2. Redistributions in binary form must reproduce the above copyright |
| 27 | * notice, this list of conditions and the following disclaimer in |
| 28 | * the documentation and/or other materials provided with the |
| 29 | * distribution. |
| 30 | * |
| 31 | * 3. All advertising materials mentioning features or use of this |
| 32 | * software must display the following acknowledgment: |
| 33 | * "This product includes software developed by the OpenSSL Project |
| 34 | * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" |
| 35 | * |
| 36 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to |
| 37 | * endorse or promote products derived from this software without |
| 38 | * prior written permission. For written permission, please contact |
| 39 | * openssl-core@OpenSSL.org. |
| 40 | * |
| 41 | * 5. Products derived from this software may not be called "OpenSSL" |
| 42 | * nor may "OpenSSL" appear in their names without prior written |
| 43 | * permission of the OpenSSL Project. |
| 44 | * |
| 45 | * 6. Redistributions of any form whatsoever must retain the following |
| 46 | * acknowledgment: |
| 47 | * "This product includes software developed by the OpenSSL Project |
| 48 | * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" |
| 49 | * |
| 50 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY |
| 51 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 52 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 53 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR |
| 54 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 55 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 56 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 57 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 58 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 59 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 60 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 61 | * OF THE POSSIBILITY OF SUCH DAMAGE. |
| 62 | * ==================================================================== |
| 63 | * |
| 64 | * This product includes cryptographic software written by Eric Young |
| 65 | * (eay@cryptsoft.com). This product includes software written by Tim |
| 66 | * Hudson (tjh@cryptsoft.com). |
| 67 | * |
| 68 | */ |
| 69 | |
| 70 | |
| 71 | #include <string.h> |
| 72 | #include <limits.h> |
| 73 | |
| 74 | #include "cryptlib.h" |
| 75 | |
| 76 | #include "ech_locl.h" |
| 77 | #include <openssl/err.h> |
| 78 | #include <openssl/sha.h> |
| 79 | #include <openssl/obj_mac.h> |
| 80 | #include <openssl/bn.h> |
| 81 | |
| 82 | static int ecdh_compute_key(void *out, size_t len, const EC_POINT *pub_key, |
| 83 | EC_KEY *ecdh, |
| 84 | void *(*KDF)(const void *in, size_t inlen, void *out, size_t *outlen)); |
| 85 | |
| 86 | static ECDH_METHOD openssl_ecdh_meth = { |
| 87 | "OpenSSL ECDH method", |
| 88 | ecdh_compute_key, |
| 89 | #if 0 |
| 90 | NULL, /* init */ |
| 91 | NULL, /* finish */ |
| 92 | #endif |
| 93 | 0, /* flags */ |
| 94 | NULL /* app_data */ |
| 95 | }; |
| 96 | |
| 97 | const ECDH_METHOD *ECDH_OpenSSL(void) |
| 98 | { |
| 99 | return &openssl_ecdh_meth; |
| 100 | } |
| 101 | |
| 102 | |
| 103 | /* This implementation is based on the following primitives in the IEEE 1363 standard: |
| 104 | * - ECKAS-DH1 |
| 105 | * - ECSVDP-DH |
| 106 | * Finally an optional KDF is applied. |
| 107 | */ |
| 108 | static int ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, |
| 109 | EC_KEY *ecdh, |
| 110 | void *(*KDF)(const void *in, size_t inlen, void *out, size_t *outlen)) |
| 111 | { |
| 112 | BN_CTX *ctx; |
| 113 | EC_POINT *tmp=NULL; |
| 114 | BIGNUM *x=NULL, *y=NULL; |
| 115 | const BIGNUM *priv_key; |
| 116 | const EC_GROUP* group; |
| 117 | int ret= -1; |
| 118 | size_t buflen, len; |
| 119 | unsigned char *buf=NULL; |
| 120 | |
| 121 | if (outlen > INT_MAX) |
| 122 | { |
| 123 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE); /* sort of, anyway */ |
| 124 | return -1; |
| 125 | } |
| 126 | |
| 127 | if ((ctx = BN_CTX_new()) == NULL) goto err; |
| 128 | BN_CTX_start(ctx); |
| 129 | x = BN_CTX_get(ctx); |
| 130 | y = BN_CTX_get(ctx); |
| 131 | |
| 132 | priv_key = EC_KEY_get0_private_key(ecdh); |
| 133 | if (priv_key == NULL) |
| 134 | { |
| 135 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_NO_PRIVATE_VALUE); |
| 136 | goto err; |
| 137 | } |
| 138 | |
| 139 | group = EC_KEY_get0_group(ecdh); |
| 140 | if ((tmp=EC_POINT_new(group)) == NULL) |
| 141 | { |
| 142 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE); |
| 143 | goto err; |
| 144 | } |
| 145 | |
| 146 | if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) |
| 147 | { |
| 148 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE); |
| 149 | goto err; |
| 150 | } |
| 151 | |
| 152 | if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) |
| 153 | { |
| 154 | if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) |
| 155 | { |
| 156 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE); |
| 157 | goto err; |
| 158 | } |
| 159 | } |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 160 | else |
| 161 | { |
| 162 | if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) |
| 163 | { |
| 164 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE); |
| 165 | goto err; |
| 166 | } |
| 167 | } |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 168 | |
| 169 | buflen = (EC_GROUP_get_degree(group) + 7)/8; |
| 170 | len = BN_num_bytes(x); |
| 171 | if (len > buflen) |
| 172 | { |
| 173 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_INTERNAL_ERROR); |
| 174 | goto err; |
| 175 | } |
| 176 | if ((buf = OPENSSL_malloc(buflen)) == NULL) |
| 177 | { |
| 178 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE); |
| 179 | goto err; |
| 180 | } |
| 181 | |
| 182 | memset(buf, 0, buflen - len); |
| 183 | if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) |
| 184 | { |
| 185 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_BN_LIB); |
| 186 | goto err; |
| 187 | } |
| 188 | |
| 189 | if (KDF != 0) |
| 190 | { |
| 191 | if (KDF(buf, buflen, out, &outlen) == NULL) |
| 192 | { |
| 193 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_KDF_FAILED); |
| 194 | goto err; |
| 195 | } |
| 196 | ret = outlen; |
| 197 | } |
| 198 | else |
| 199 | { |
| 200 | /* no KDF, just copy as much as we can */ |
| 201 | if (outlen > buflen) |
| 202 | outlen = buflen; |
| 203 | memcpy(out, buf, outlen); |
| 204 | ret = outlen; |
| 205 | } |
| 206 | |
| 207 | err: |
| 208 | if (tmp) EC_POINT_free(tmp); |
| 209 | if (ctx) BN_CTX_end(ctx); |
| 210 | if (ctx) BN_CTX_free(ctx); |
| 211 | if (buf) OPENSSL_free(buf); |
| 212 | return(ret); |
| 213 | } |