Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 1 | /* ==================================================================== |
| 2 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. |
| 3 | * |
| 4 | * The Elliptic Curve Public-Key Crypto Library (ECC Code) included |
| 5 | * herein is developed by SUN MICROSYSTEMS, INC., and is contributed |
| 6 | * to the OpenSSL project. |
| 7 | * |
| 8 | * The ECC Code is licensed pursuant to the OpenSSL open source |
| 9 | * license provided below. |
| 10 | * |
| 11 | * The ECDH software is originally written by Douglas Stebila of |
| 12 | * Sun Microsystems Laboratories. |
| 13 | * |
| 14 | */ |
| 15 | /* ==================================================================== |
| 16 | * Copyright (c) 2000-2002 The OpenSSL Project. All rights reserved. |
| 17 | * |
| 18 | * Redistribution and use in source and binary forms, with or without |
| 19 | * modification, are permitted provided that the following conditions |
| 20 | * are met: |
| 21 | * |
| 22 | * 1. Redistributions of source code must retain the above copyright |
| 23 | * notice, this list of conditions and the following disclaimer. |
| 24 | * |
| 25 | * 2. Redistributions in binary form must reproduce the above copyright |
| 26 | * notice, this list of conditions and the following disclaimer in |
| 27 | * the documentation and/or other materials provided with the |
| 28 | * distribution. |
| 29 | * |
| 30 | * 3. All advertising materials mentioning features or use of this |
| 31 | * software must display the following acknowledgment: |
| 32 | * "This product includes software developed by the OpenSSL Project |
| 33 | * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" |
| 34 | * |
| 35 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to |
| 36 | * endorse or promote products derived from this software without |
| 37 | * prior written permission. For written permission, please contact |
| 38 | * licensing@OpenSSL.org. |
| 39 | * |
| 40 | * 5. Products derived from this software may not be called "OpenSSL" |
| 41 | * nor may "OpenSSL" appear in their names without prior written |
| 42 | * permission of the OpenSSL Project. |
| 43 | * |
| 44 | * 6. Redistributions of any form whatsoever must retain the following |
| 45 | * acknowledgment: |
| 46 | * "This product includes software developed by the OpenSSL Project |
| 47 | * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" |
| 48 | * |
| 49 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY |
| 50 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 51 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 52 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR |
| 53 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 54 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 55 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 56 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 57 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 58 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 59 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| 60 | * OF THE POSSIBILITY OF SUCH DAMAGE. |
| 61 | * ==================================================================== |
| 62 | * |
| 63 | * This product includes cryptographic software written by Eric Young |
| 64 | * (eay@cryptsoft.com). This product includes software written by Tim |
| 65 | * Hudson (tjh@cryptsoft.com). */ |
| 66 | |
| 67 | #include <openssl/ecdh.h> |
| 68 | |
Adam Langley | 2b2d66d | 2015-01-30 17:08:37 -0800 | [diff] [blame] | 69 | #include <string.h> |
| 70 | |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 71 | #include <openssl/bn.h> |
| 72 | #include <openssl/digest.h> |
| 73 | #include <openssl/err.h> |
| 74 | #include <openssl/mem.h> |
| 75 | |
| 76 | |
| 77 | int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 78 | EC_KEY *priv_key, |
| 79 | void *(*kdf)(const void *in, size_t inlen, void *out, |
| 80 | size_t *outlen)) { |
| 81 | const BIGNUM *const priv = EC_KEY_get0_private_key(priv_key); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 82 | if (priv == NULL) { |
David Benjamin | 3570d73 | 2015-06-29 00:28:17 -0400 | [diff] [blame] | 83 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE); |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 84 | return -1; |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 85 | } |
| 86 | |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 87 | BN_CTX *ctx = BN_CTX_new(); |
| 88 | if (ctx == NULL) { |
| 89 | return -1; |
| 90 | } |
| 91 | BN_CTX_start(ctx); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 92 | |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 93 | int ret = -1; |
| 94 | size_t buflen = 0; |
| 95 | uint8_t *buf = NULL; |
| 96 | |
| 97 | const EC_GROUP *const group = EC_KEY_get0_group(priv_key); |
| 98 | EC_POINT *tmp = EC_POINT_new(group); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 99 | if (tmp == NULL) { |
David Benjamin | 3570d73 | 2015-06-29 00:28:17 -0400 | [diff] [blame] | 100 | OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 101 | goto err; |
| 102 | } |
| 103 | |
| 104 | if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv, ctx)) { |
David Benjamin | 3570d73 | 2015-06-29 00:28:17 -0400 | [diff] [blame] | 105 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 106 | goto err; |
| 107 | } |
| 108 | |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 109 | BIGNUM *x = BN_CTX_get(ctx); |
| 110 | if (!x) { |
| 111 | OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE); |
| 112 | goto err; |
| 113 | } |
| 114 | |
| 115 | if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, NULL, ctx)) { |
David Benjamin | 3570d73 | 2015-06-29 00:28:17 -0400 | [diff] [blame] | 116 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 117 | goto err; |
| 118 | } |
| 119 | |
| 120 | buflen = (EC_GROUP_get_degree(group) + 7) / 8; |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 121 | buf = OPENSSL_malloc(buflen); |
| 122 | if (buf == NULL) { |
David Benjamin | 3570d73 | 2015-06-29 00:28:17 -0400 | [diff] [blame] | 123 | OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 124 | goto err; |
| 125 | } |
| 126 | |
David Benjamin | f2f3cfe | 2014-11-10 17:28:53 -0500 | [diff] [blame] | 127 | if (!BN_bn2bin_padded(buf, buflen, x)) { |
David Benjamin | 3570d73 | 2015-06-29 00:28:17 -0400 | [diff] [blame] | 128 | OPENSSL_PUT_ERROR(ECDH, ERR_R_INTERNAL_ERROR); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 129 | goto err; |
| 130 | } |
| 131 | |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 132 | if (kdf != NULL) { |
| 133 | if (kdf(buf, buflen, out, &outlen) == NULL) { |
David Benjamin | 3570d73 | 2015-06-29 00:28:17 -0400 | [diff] [blame] | 134 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_KDF_FAILED); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 135 | goto err; |
| 136 | } |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 137 | } else { |
| 138 | /* no KDF, just copy as much as we can */ |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 139 | if (buflen < outlen) { |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 140 | outlen = buflen; |
| 141 | } |
| 142 | memcpy(out, buf, outlen); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 143 | } |
| 144 | |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 145 | ret = outlen; |
| 146 | |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 147 | err: |
Brian Smith | 0dc2a8a | 2015-10-08 11:52:56 -1000 | [diff] [blame^] | 148 | OPENSSL_free(buf); |
| 149 | EC_POINT_free(tmp); |
| 150 | BN_CTX_end(ctx); |
| 151 | BN_CTX_free(ctx); |
Adam Langley | 95c29f3 | 2014-06-20 12:00:00 -0700 | [diff] [blame] | 152 | return ret; |
| 153 | } |