| /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
| * All rights reserved. |
| * |
| * This package is an SSL implementation written |
| * by Eric Young (eay@cryptsoft.com). |
| * The implementation was written so as to conform with Netscapes SSL. |
| * |
| * This library is free for commercial and non-commercial use as long as |
| * the following conditions are aheared to. The following conditions |
| * apply to all code found in this distribution, be it the RC4, RSA, |
| * lhash, DES, etc., code; not just the SSL code. The SSL documentation |
| * included with this distribution is covered by the same copyright terms |
| * except that the holder is Tim Hudson (tjh@cryptsoft.com). |
| * |
| * Copyright remains Eric Young's, and as such any Copyright notices in |
| * the code are not to be removed. |
| * If this package is used in a product, Eric Young should be given attribution |
| * as the author of the parts of the library used. |
| * This can be in the form of a textual message at program startup or |
| * in documentation (online or textual) provided with the package. |
| * |
| * 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 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 acknowledgement: |
| * "This product includes cryptographic software written by |
| * Eric Young (eay@cryptsoft.com)" |
| * The word 'cryptographic' can be left out if the rouines from the library |
| * being used are not cryptographic related :-). |
| * 4. If you include any Windows specific code (or a derivative thereof) from |
| * the apps directory (application code) you must include an acknowledgement: |
| * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" |
| * |
| * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
| * ANY EXPRESS 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 AUTHOR OR 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. |
| * |
| * The licence and distribution terms for any publically available version or |
| * derivative of this code cannot be changed. i.e. this code cannot simply be |
| * copied and put under another distribution licence |
| * [including the GNU Public Licence.] */ |
| |
| #include <openssl/dh.h> |
| |
| #include <openssl/bn.h> |
| |
| |
| int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *out_flags) { |
| *out_flags = 0; |
| |
| BN_CTX *ctx = BN_CTX_new(); |
| if (ctx == NULL) { |
| return 0; |
| } |
| BN_CTX_start(ctx); |
| |
| int ok = 0; |
| |
| /* Check |pub_key| is greater than 1. */ |
| BIGNUM *tmp = BN_CTX_get(ctx); |
| if (tmp == NULL || |
| !BN_set_word(tmp, 1)) { |
| goto err; |
| } |
| if (BN_cmp(pub_key, tmp) <= 0) { |
| *out_flags |= DH_CHECK_PUBKEY_TOO_SMALL; |
| } |
| |
| /* Check |pub_key| is less than |dh->p| - 1. */ |
| if (!BN_copy(tmp, dh->p) || |
| !BN_sub_word(tmp, 1)) { |
| goto err; |
| } |
| if (BN_cmp(pub_key, tmp) >= 0) { |
| *out_flags |= DH_CHECK_PUBKEY_TOO_LARGE; |
| } |
| |
| if (dh->q != NULL) { |
| /* Check |pub_key|^|dh->q| is 1 mod |dh->p|. This is necessary for RFC 5114 |
| * groups which are not safe primes but pick a generator on a prime-order |
| * subgroup of size |dh->q|. */ |
| if (!BN_mod_exp_mont(tmp, pub_key, dh->q, dh->p, ctx, NULL)) { |
| goto err; |
| } |
| if (!BN_is_one(tmp)) { |
| *out_flags |= DH_CHECK_PUBKEY_INVALID; |
| } |
| } |
| |
| ok = 1; |
| |
| err: |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| return ok; |
| } |
| |
| |
| int DH_check(const DH *dh, int *out_flags) { |
| /* Check that p is a safe prime and if g is 2, 3 or 5, check that it is a |
| * suitable generator where: |
| * for 2, p mod 24 == 11 |
| * for 3, p mod 12 == 5 |
| * for 5, p mod 10 == 3 or 7 |
| * should hold. |
| */ |
| int ok = 0, r; |
| BN_CTX *ctx = NULL; |
| BN_ULONG l; |
| BIGNUM *t1 = NULL, *t2 = NULL; |
| |
| *out_flags = 0; |
| ctx = BN_CTX_new(); |
| if (ctx == NULL) { |
| goto err; |
| } |
| BN_CTX_start(ctx); |
| t1 = BN_CTX_get(ctx); |
| if (t1 == NULL) { |
| goto err; |
| } |
| t2 = BN_CTX_get(ctx); |
| if (t2 == NULL) { |
| goto err; |
| } |
| |
| if (dh->q) { |
| if (BN_cmp(dh->g, BN_value_one()) <= 0) { |
| *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; |
| } else if (BN_cmp(dh->g, dh->p) >= 0) { |
| *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; |
| } else { |
| /* Check g^q == 1 mod p */ |
| if (!BN_mod_exp_mont(t1, dh->g, dh->q, dh->p, ctx, NULL)) { |
| goto err; |
| } |
| if (!BN_is_one(t1)) { |
| *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; |
| } |
| } |
| r = BN_is_prime_ex(dh->q, BN_prime_checks, ctx, NULL); |
| if (r < 0) { |
| goto err; |
| } |
| if (!r) { |
| *out_flags |= DH_CHECK_Q_NOT_PRIME; |
| } |
| /* Check p == 1 mod q i.e. q divides p - 1 */ |
| if (!BN_div(t1, t2, dh->p, dh->q, ctx)) { |
| goto err; |
| } |
| if (!BN_is_one(t2)) { |
| *out_flags |= DH_CHECK_INVALID_Q_VALUE; |
| } |
| if (dh->j && BN_cmp(dh->j, t1)) { |
| *out_flags |= DH_CHECK_INVALID_J_VALUE; |
| } |
| } else if (BN_is_word(dh->g, DH_GENERATOR_2)) { |
| l = BN_mod_word(dh->p, 24); |
| if (l == (BN_ULONG)-1) { |
| goto err; |
| } |
| if (l != 11) { |
| *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; |
| } |
| } else if (BN_is_word(dh->g, DH_GENERATOR_5)) { |
| l = BN_mod_word(dh->p, 10); |
| if (l == (BN_ULONG)-1) { |
| goto err; |
| } |
| if (l != 3 && l != 7) { |
| *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; |
| } |
| } else { |
| *out_flags |= DH_CHECK_UNABLE_TO_CHECK_GENERATOR; |
| } |
| |
| r = BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL); |
| if (r < 0) { |
| goto err; |
| } |
| if (!r) { |
| *out_flags |= DH_CHECK_P_NOT_PRIME; |
| } else if (!dh->q) { |
| if (!BN_rshift1(t1, dh->p)) { |
| goto err; |
| } |
| r = BN_is_prime_ex(t1, BN_prime_checks, ctx, NULL); |
| if (r < 0) { |
| goto err; |
| } |
| if (!r) { |
| *out_flags |= DH_CHECK_P_NOT_SAFE_PRIME; |
| } |
| } |
| ok = 1; |
| |
| err: |
| if (ctx != NULL) { |
| BN_CTX_end(ctx); |
| BN_CTX_free(ctx); |
| } |
| return ok; |
| } |