diff options
Diffstat (limited to 'src/crypto/dh/check.c')
| -rw-r--r-- | src/crypto/dh/check.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/src/crypto/dh/check.c b/src/crypto/dh/check.c new file mode 100644 index 0000000..06af6f2 --- /dev/null +++ b/src/crypto/dh/check.c @@ -0,0 +1,180 @@ +/* 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> + +#include "internal.h" + + +int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret) { + int ok = 0; + BIGNUM q; + + *ret = 0; + BN_init(&q); + if (!BN_set_word(&q, 1)) { + goto err; + } + + if (BN_cmp(pub_key, &q) <= 0) { + *ret |= DH_CHECK_PUBKEY_TOO_SMALL; + } + if (!BN_copy(&q, dh->p) || + !BN_sub_word(&q, 1)) { + goto err; + } + if (BN_cmp(pub_key, &q) >= 0) { + *ret |= DH_CHECK_PUBKEY_TOO_LARGE; + } + + ok = 1; + +err: + BN_free(&q); + return ok; +} + + +int DH_check(const DH *dh, int *ret) { + /* 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; + BN_CTX *ctx = NULL; + BN_ULONG l; + BIGNUM *t1 = NULL, *t2 = NULL; + + *ret = 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) { + *ret |= DH_CHECK_NOT_SUITABLE_GENERATOR; + } else if (BN_cmp(dh->g, dh->p) >= 0) { + *ret |= DH_CHECK_NOT_SUITABLE_GENERATOR; + } else { + /* Check g^q == 1 mod p */ + if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx)) { + goto err; + } + if (!BN_is_one(t1)) { + *ret |= DH_CHECK_NOT_SUITABLE_GENERATOR; + } + } + if (!BN_is_prime_ex(dh->q, BN_prime_checks, ctx, NULL)) { + *ret |= 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)) { + *ret |= DH_CHECK_INVALID_Q_VALUE; + } + if (dh->j && BN_cmp(dh->j, t1)) { + *ret |= DH_CHECK_INVALID_J_VALUE; + } + } else if (BN_is_word(dh->g, DH_GENERATOR_2)) { + l = BN_mod_word(dh->p, 24); + if (l != 11) { + *ret |= DH_CHECK_NOT_SUITABLE_GENERATOR; + } + } else if (BN_is_word(dh->g, DH_GENERATOR_5)) { + l = BN_mod_word(dh->p, 10); + if (l != 3 && l != 7) { + *ret |= DH_CHECK_NOT_SUITABLE_GENERATOR; + } + } else { + *ret |= DH_CHECK_UNABLE_TO_CHECK_GENERATOR; + } + + if (!BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL)) { + *ret |= DH_CHECK_P_NOT_PRIME; + } else if (!dh->q) { + if (!BN_rshift1(t1, dh->p)) { + goto err; + } + if (!BN_is_prime_ex(t1, BN_prime_checks, ctx, NULL)) { + *ret |= DH_CHECK_P_NOT_SAFE_PRIME; + } + } + ok = 1; + +err: + if (ctx != NULL) { + BN_CTX_end(ctx); + BN_CTX_free(ctx); + } + return ok; +} |