pigweed / third_party / boringssl / boringssl / 8fb19217a0946cc9f9e7cae21e2708e5dc026e46 / . / crypto / dh / check.c

/* 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; | |

} |