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yuzu/externals/libressl/crypto/dh/dh_check.c

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/* $OpenBSD: dh_check.c,v 1.24 2022/01/10 12:00:52 tb Exp $ */
/* 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 <stdio.h>
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include "bn_lcl.h"
#include "dh_local.h"
#define DH_NUMBER_ITERATIONS_FOR_PRIME 64
/*
* Check that p is odd and 1 < g < p - 1. The _ex version removes the need of
* inspecting flags and pushes errors on the stack instead.
*/
int
DH_check_params_ex(const DH *dh)
{
int flags = 0;
if (!DH_check_params(dh, &flags))
return 0;
if ((flags & DH_CHECK_P_NOT_PRIME) != 0)
DHerror(DH_R_CHECK_P_NOT_PRIME);
if ((flags & DH_NOT_SUITABLE_GENERATOR) != 0)
DHerror(DH_R_NOT_SUITABLE_GENERATOR);
return flags == 0;
}
int
DH_check_params(const DH *dh, int *flags)
{
BIGNUM *max_g = NULL;
int ok = 0;
*flags = 0;
if (!BN_is_odd(dh->p))
*flags |= DH_CHECK_P_NOT_PRIME;
/*
* Check that 1 < dh->g < p - 1
*/
if (BN_cmp(dh->g, BN_value_one()) <= 0)
*flags |= DH_NOT_SUITABLE_GENERATOR;
/* max_g = p - 1 */
if ((max_g = BN_dup(dh->p)) == NULL)
goto err;
if (!BN_sub_word(max_g, 1))
goto err;
/* check that g < max_g */
if (BN_cmp(dh->g, max_g) >= 0)
*flags |= DH_NOT_SUITABLE_GENERATOR;
ok = 1;
err:
BN_free(max_g);
return ok;
}
/*
* Check that p is a safe prime and that g is a suitable generator.
* The _ex version puts errors on the stack instead of returning flags.
*/
int
DH_check_ex(const DH *dh)
{
int flags = 0;
if (!DH_check(dh, &flags))
return 0;
if ((flags & DH_NOT_SUITABLE_GENERATOR) != 0)
DHerror(DH_R_NOT_SUITABLE_GENERATOR);
if ((flags & DH_CHECK_Q_NOT_PRIME) != 0)
DHerror(DH_R_CHECK_Q_NOT_PRIME);
if ((flags & DH_CHECK_INVALID_Q_VALUE) != 0)
DHerror(DH_R_CHECK_INVALID_Q_VALUE);
if ((flags & DH_CHECK_INVALID_J_VALUE) != 0)
DHerror(DH_R_CHECK_INVALID_J_VALUE);
if ((flags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
DHerror(DH_R_UNABLE_TO_CHECK_GENERATOR);
if ((flags & DH_CHECK_P_NOT_PRIME) != 0)
DHerror(DH_R_CHECK_P_NOT_PRIME);
if ((flags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
DHerror(DH_R_CHECK_P_NOT_SAFE_PRIME);
return flags == 0;
}
int
DH_check(const DH *dh, int *flags)
{
BN_CTX *ctx = NULL;
int is_prime;
int ok = 0;
*flags = 0;
if (!DH_check_params(dh, flags))
goto err;
ctx = BN_CTX_new();
if (ctx == NULL)
goto err;
BN_CTX_start(ctx);
if (dh->q != NULL) {
BIGNUM *quotient, *residue;
if ((quotient = BN_CTX_get(ctx)) == NULL)
goto err;
if ((residue = BN_CTX_get(ctx)) == NULL)
goto err;
if ((*flags & DH_NOT_SUITABLE_GENERATOR) == 0) {
/* Check g^q == 1 mod p */
if (!BN_mod_exp_ct(residue, dh->g, dh->q, dh->p, ctx))
goto err;
if (!BN_is_one(residue))
*flags |= DH_NOT_SUITABLE_GENERATOR;
}
is_prime = BN_is_prime_ex(dh->q, DH_NUMBER_ITERATIONS_FOR_PRIME,
ctx, NULL);
if (is_prime < 0)
goto err;
if (is_prime == 0)
*flags |= DH_CHECK_Q_NOT_PRIME;
/* Check p == 1 mod q, i.e., q divides p - 1 */
if (!BN_div_ct(quotient, residue, dh->p, dh->q, ctx))
goto err;
if (!BN_is_one(residue))
*flags |= DH_CHECK_INVALID_Q_VALUE;
if (dh->j != NULL && BN_cmp(dh->j, quotient) != 0)
*flags |= DH_CHECK_INVALID_J_VALUE;
}
is_prime = BN_is_prime_ex(dh->p, DH_NUMBER_ITERATIONS_FOR_PRIME,
ctx, NULL);
if (is_prime < 0)
goto err;
if (is_prime == 0)
*flags |= DH_CHECK_P_NOT_PRIME;
else if (dh->q == NULL) {
BIGNUM *q;
if ((q = BN_CTX_get(ctx)) == NULL)
goto err;
if (!BN_rshift1(q, dh->p))
goto err;
is_prime = BN_is_prime_ex(q, DH_NUMBER_ITERATIONS_FOR_PRIME,
ctx, NULL);
if (is_prime < 0)
goto err;
if (is_prime == 0)
*flags |= DH_CHECK_P_NOT_SAFE_PRIME;
}
ok = 1;
err:
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ok;
}
int
DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
{
int flags = 0;
if (!DH_check_pub_key(dh, pub_key, &flags))
return 0;
if ((flags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
DHerror(DH_R_CHECK_PUBKEY_TOO_SMALL);
if ((flags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
DHerror(DH_R_CHECK_PUBKEY_TOO_LARGE);
if ((flags & DH_CHECK_PUBKEY_INVALID) != 0)
DHerror(DH_R_CHECK_PUBKEY_INVALID);
return flags == 0;
}
int
DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *flags)
{
BN_CTX *ctx = NULL;
BIGNUM *max_pub_key;
int ok = 0;
*flags = 0;
if ((ctx = BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
if ((max_pub_key = BN_CTX_get(ctx)) == NULL)
goto err;
/*
* Check that 1 < pub_key < dh->p - 1
*/
if (BN_cmp(pub_key, BN_value_one()) <= 0)
*flags |= DH_CHECK_PUBKEY_TOO_SMALL;
/* max_pub_key = dh->p - 1 */
if (BN_copy(max_pub_key, dh->p) == NULL)
goto err;
if (!BN_sub_word(max_pub_key, 1))
goto err;
if (BN_cmp(pub_key, max_pub_key) >= 0)
*flags |= DH_CHECK_PUBKEY_TOO_LARGE;
/*
* If dh->q is set, check that pub_key^q == 1 mod p
*/
if (dh->q != NULL) {
BIGNUM *residue;
if ((residue = BN_CTX_get(ctx)) == NULL)
goto err;
if (!BN_mod_exp_ct(residue, pub_key, dh->q, dh->p, ctx))
goto err;
if (!BN_is_one(residue))
*flags = DH_CHECK_PUBKEY_INVALID;
}
ok = 1;
err:
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ok;
}
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