Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [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 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 69 | #include <limits.h> |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 70 | #include <string.h> |
| 71 | |
| 72 | #include <openssl/bn.h> |
| 73 | #include <openssl/digest.h> |
| 74 | #include <openssl/err.h> |
| 75 | #include <openssl/mem.h> |
| 76 | |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 77 | #include "../internal.h" |
| 78 | |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 79 | |
| 80 | int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, |
David Benjamin | 95add82 | 2016-10-19 01:09:12 -0400 | [diff] [blame] | 81 | const EC_KEY *priv_key, |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 82 | void *(*kdf)(const void *in, size_t inlen, void *out, |
| 83 | size_t *outlen)) { |
| 84 | const BIGNUM *const priv = EC_KEY_get0_private_key(priv_key); |
Kenny Root | 03bcf61 | 2015-11-05 20:20:27 +0000 | [diff] [blame] | 85 | if (priv == NULL) { |
| 86 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE); |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 87 | return -1; |
Kenny Root | 03bcf61 | 2015-11-05 20:20:27 +0000 | [diff] [blame] | 88 | } |
| 89 | |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 90 | BN_CTX *ctx = BN_CTX_new(); |
| 91 | if (ctx == NULL) { |
| 92 | return -1; |
| 93 | } |
| 94 | BN_CTX_start(ctx); |
Kenny Root | 03bcf61 | 2015-11-05 20:20:27 +0000 | [diff] [blame] | 95 | |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 96 | int ret = -1; |
| 97 | size_t buflen = 0; |
| 98 | uint8_t *buf = NULL; |
| 99 | |
| 100 | const EC_GROUP *const group = EC_KEY_get0_group(priv_key); |
| 101 | EC_POINT *tmp = EC_POINT_new(group); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 102 | if (tmp == NULL) { |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 103 | OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 104 | goto err; |
| 105 | } |
| 106 | |
| 107 | if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv, ctx)) { |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 108 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 109 | goto err; |
| 110 | } |
| 111 | |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 112 | BIGNUM *x = BN_CTX_get(ctx); |
| 113 | if (!x) { |
| 114 | OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE); |
| 115 | goto err; |
| 116 | } |
| 117 | |
| 118 | if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, NULL, ctx)) { |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 119 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 120 | goto err; |
| 121 | } |
| 122 | |
| 123 | buflen = (EC_GROUP_get_degree(group) + 7) / 8; |
| 124 | buf = OPENSSL_malloc(buflen); |
| 125 | if (buf == NULL) { |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 126 | OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 127 | goto err; |
| 128 | } |
| 129 | |
| 130 | if (!BN_bn2bin_padded(buf, buflen, x)) { |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 131 | OPENSSL_PUT_ERROR(ECDH, ERR_R_INTERNAL_ERROR); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 132 | goto err; |
| 133 | } |
| 134 | |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 135 | if (kdf != NULL) { |
| 136 | if (kdf(buf, buflen, out, &outlen) == NULL) { |
Kenny Root | b849459 | 2015-09-25 02:29:14 +0000 | [diff] [blame] | 137 | OPENSSL_PUT_ERROR(ECDH, ECDH_R_KDF_FAILED); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 138 | goto err; |
| 139 | } |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 140 | } else { |
Robert Sloan | 8f860b1 | 2017-08-28 07:37:06 -0700 | [diff] [blame] | 141 | // no KDF, just copy as much as we can |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 142 | if (buflen < outlen) { |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 143 | outlen = buflen; |
| 144 | } |
Robert Sloan | 69939df | 2017-01-09 10:53:07 -0800 | [diff] [blame] | 145 | OPENSSL_memcpy(out, buf, outlen); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 146 | } |
| 147 | |
David Benjamin | c895d6b | 2016-08-11 13:26:41 -0400 | [diff] [blame] | 148 | if (outlen > INT_MAX) { |
| 149 | OPENSSL_PUT_ERROR(ECDH, ERR_R_OVERFLOW); |
| 150 | goto err; |
| 151 | } |
| 152 | |
| 153 | ret = (int)outlen; |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 154 | |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 155 | err: |
Kenny Root | e99801b | 2015-11-06 15:31:15 -0800 | [diff] [blame] | 156 | OPENSSL_free(buf); |
| 157 | EC_POINT_free(tmp); |
| 158 | BN_CTX_end(ctx); |
| 159 | BN_CTX_free(ctx); |
Adam Langley | d9e397b | 2015-01-22 14:27:53 -0800 | [diff] [blame] | 160 | return ret; |
| 161 | } |