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/*
* Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* Finite Field cryptography (FFC) is used for DSA and DH.
* This file contains methods for validation of FFC parameters.
* It calls the same functions as the generation as the code is very similar.
*/
#include "internal/ffc.h"
/* FIPS186-4 A.2.2 Unverifiable partial validation of Generator g */
int ffc_params_validate_unverifiable_g(BN_CTX *ctx, BN_MONT_CTX *mont,
const BIGNUM *p, const BIGNUM *q,
const BIGNUM *g, BIGNUM *tmp, int *ret)
{
/*
* A.2.2 Step (1) AND
* A.2.4 Step (2)
* Verify that 2 <= g <= (p - 1)
*/
if (BN_cmp(g, BN_value_one()) <= 0 || BN_cmp(g, p) >= 0) {
*ret |= FFC_ERROR_NOT_SUITABLE_GENERATOR;
return 0;
}
/*
* A.2.2 Step (2) AND
* A.2.4 Step (3)
* Check g^q mod p = 1
*/
if (!BN_mod_exp_mont(tmp, g, q, p, ctx, mont))
return 0;
if (BN_cmp(tmp, BN_value_one()) != 0) {
*ret |= FFC_ERROR_NOT_SUITABLE_GENERATOR;
return 0;
}
return 1;
}
int ffc_params_FIPS186_4_validate(OPENSSL_CTX *libctx, const FFC_PARAMS *params,
int type, int *res, BN_GENCB *cb)
{
size_t L, N;
if (params == NULL || params->p == NULL || params->q == NULL)
return FFC_PARAM_RET_STATUS_FAILED;
/* A.1.1.3 Step (1..2) : L = len(p), N = len(q) */
L = BN_num_bits(params->p);
N = BN_num_bits(params->q);
return ffc_params_FIPS186_4_gen_verify(libctx, (FFC_PARAMS *)params,
FFC_PARAM_MODE_VERIFY, type,
L, N, res, cb);
}
/* This may be used in FIPS mode to validate deprecated FIPS-186-2 Params */
int ffc_params_FIPS186_2_validate(OPENSSL_CTX *libctx, const FFC_PARAMS *params,
int type, int *res, BN_GENCB *cb)
{
size_t L, N;
if (params->p == NULL || params->q == NULL) {
*res = FFC_CHECK_INVALID_PQ;
return FFC_PARAM_RET_STATUS_FAILED;
}
/* A.1.1.3 Step (1..2) : L = len(p), N = len(q) */
L = BN_num_bits(params->p);
N = BN_num_bits(params->q);
return ffc_params_FIPS186_2_gen_verify(libctx, (FFC_PARAMS *)params,
FFC_PARAM_MODE_VERIFY, type,
L, N, res, cb);
}
/*
* This does a simple check of L and N and partial g.
* It makes no attempt to do a full validation of p, q or g since these require
* extra parameters such as the digest and seed, which may not be available for
* this test.
*/
int ffc_params_simple_validate(OPENSSL_CTX *libctx, FFC_PARAMS *params, int type)
{
int ret, res = 0;
int save_gindex;
unsigned int save_flags;
if (params == NULL)
return 0;
save_flags = params->flags;
save_gindex = params->gindex;
params->flags = FFC_PARAM_FLAG_VALIDATE_G;
params->gindex = FFC_UNVERIFIABLE_GINDEX;
ret = ffc_params_FIPS186_4_validate(libctx, params, type, &res, NULL);
params->flags = save_flags;
params->gindex = save_gindex;
return ret != FFC_PARAM_RET_STATUS_FAILED;
}
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