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/*
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* Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <stdio.h>
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#include "internal/cryptlib.h"
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#include <openssl/bn.h>
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#include <openssl/obj_mac.h>
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#include "dh_local.h"
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# define DH_NUMBER_ITERATIONS_FOR_PRIME 64
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/*-
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* Check that p and g are suitable enough
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*
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* p is odd
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* 1 < g < p - 1
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*/
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int DH_check_params_ex(const DH *dh)
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{
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int errflags = 0;
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if (!DH_check_params(dh, &errflags))
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return 0;
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if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
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DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_CHECK_P_NOT_PRIME);
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if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
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DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_NOT_SUITABLE_GENERATOR);
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return errflags == 0;
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}
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int DH_check_params(const DH *dh, int *ret)
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{
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int ok = 0;
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BIGNUM *tmp = NULL;
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BN_CTX *ctx = NULL;
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if (FIPS_mode()) {
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int nid = dh->nid == NID_undef ? DH_get_nid(dh) : dh->nid;
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return nid != NID_undef;
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}
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*ret = 0;
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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tmp = BN_CTX_get(ctx);
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if (tmp == NULL)
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goto err;
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if (!BN_is_odd(dh->p))
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*ret |= DH_CHECK_P_NOT_PRIME;
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if (BN_is_negative(dh->g) || BN_is_zero(dh->g) || BN_is_one(dh->g))
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
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goto err;
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if (BN_cmp(dh->g, tmp) >= 0)
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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ok = 1;
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err:
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ok;
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}
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/*-
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* Check that p is a safe prime and
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* g is a suitable generator.
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*/
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int DH_check_ex(const DH *dh)
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{
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int errflags = 0;
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if (!DH_check(dh, &errflags))
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return 0;
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if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
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DHerr(DH_F_DH_CHECK_EX, DH_R_NOT_SUITABLE_GENERATOR);
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if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
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DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_Q_NOT_PRIME);
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if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
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DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_Q_VALUE);
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if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
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DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_J_VALUE);
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if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
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DHerr(DH_F_DH_CHECK_EX, DH_R_UNABLE_TO_CHECK_GENERATOR);
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if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
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DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_PRIME);
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if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
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DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_SAFE_PRIME);
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return errflags == 0;
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}
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/* Note: according to documentation - this only checks the params */
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int DH_check(const DH *dh, int *ret)
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{
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int ok = 0, r;
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BN_CTX *ctx = NULL;
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BIGNUM *t1 = NULL, *t2 = NULL;
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if (!DH_check_params(dh, ret))
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return 0;
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if (FIPS_mode()) /* we allow only well-known params */
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return 1;
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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t1 = BN_CTX_get(ctx);
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t2 = BN_CTX_get(ctx);
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if (t2 == NULL)
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goto err;
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if (dh->q) {
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if (BN_cmp(dh->g, BN_value_one()) <= 0)
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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else if (BN_cmp(dh->g, dh->p) >= 0)
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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else {
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/* Check g^q == 1 mod p */
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if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx))
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goto err;
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if (!BN_is_one(t1))
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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}
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r = BN_is_prime_ex(dh->q, DH_NUMBER_ITERATIONS_FOR_PRIME, ctx, NULL);
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if (r < 0)
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goto err;
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if (!r)
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*ret |= DH_CHECK_Q_NOT_PRIME;
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/* Check p == 1 mod q i.e. q divides p - 1 */
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if (!BN_div(t1, t2, dh->p, dh->q, ctx))
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goto err;
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if (!BN_is_one(t2))
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*ret |= DH_CHECK_INVALID_Q_VALUE;
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if (dh->j && BN_cmp(dh->j, t1))
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*ret |= DH_CHECK_INVALID_J_VALUE;
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}
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r = BN_is_prime_ex(dh->p, DH_NUMBER_ITERATIONS_FOR_PRIME, ctx, NULL);
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if (r < 0)
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goto err;
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if (!r)
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*ret |= DH_CHECK_P_NOT_PRIME;
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else if (!dh->q) {
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if (!BN_rshift1(t1, dh->p))
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goto err;
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r = BN_is_prime_ex(t1, DH_NUMBER_ITERATIONS_FOR_PRIME, ctx, NULL);
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if (r < 0)
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goto err;
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if (!r)
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*ret |= DH_CHECK_P_NOT_SAFE_PRIME;
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}
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ok = 1;
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err:
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ok;
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}
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int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
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{
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int errflags = 0;
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if (!DH_check_pub_key(dh, pub_key, &errflags))
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return 0;
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if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
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DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_SMALL);
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if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
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DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_LARGE);
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if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
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DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_INVALID);
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return errflags == 0;
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}
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static int dh_check_pub_key_int(const DH *dh, const BIGNUM *q, const BIGNUM *pub_key, int *ret)
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{
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int ok = 0;
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BIGNUM *tmp = NULL;
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BN_CTX *ctx = NULL;
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*ret = 0;
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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tmp = BN_CTX_get(ctx);
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if (tmp == NULL || !BN_set_word(tmp, 1))
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goto err;
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if (BN_cmp(pub_key, tmp) <= 0)
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*ret |= DH_CHECK_PUBKEY_TOO_SMALL;
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if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
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goto err;
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if (BN_cmp(pub_key, tmp) >= 0)
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*ret |= DH_CHECK_PUBKEY_TOO_LARGE;
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if (q != NULL) {
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/* Check pub_key^q == 1 mod p */
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if (!BN_mod_exp(tmp, pub_key, q, dh->p, ctx))
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goto err;
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if (!BN_is_one(tmp))
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*ret |= DH_CHECK_PUBKEY_INVALID;
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}
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ok = 1;
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err:
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ok;
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}
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int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
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{
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return dh_check_pub_key_int(dh, dh->q, pub_key, ret);
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}
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int dh_check_pub_key_full(const DH *dh, const BIGNUM *pub_key, int *ret)
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{
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BIGNUM *q = dh->q;
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if (q == NULL) {
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if (dh_get_known_q(dh, &q) == 0) {
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*ret |= DH_CHECK_INVALID_Q_VALUE;
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return 0;
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}
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}
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c4476c |
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return dh_check_pub_key_int(dh, q, pub_key, ret);
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}
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