/*

 * Copyright 1995-2024 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

 */

/*

 * DSA low level APIs are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#include <stdio.h>

#include "internal/cryptlib.h"

#include <openssl/bn.h>

#include "dsa_local.h"

#include "crypto/dsa.h"

static int dsa_precheck_params(const DSA *dsa, int *ret)

{

    if (dsa->params.p == NULL || dsa->params.q == NULL) {

        ERR_raise(ERR_LIB_DSA, DSA_R_BAD_FFC_PARAMETERS);

        *ret = FFC_CHECK_INVALID_PQ;

        return 0;

    }

    if (BN_num_bits(dsa->params.p) > OPENSSL_DSA_MAX_MODULUS_BITS) {

        ERR_raise(ERR_LIB_DSA, DSA_R_MODULUS_TOO_LARGE);

        *ret = FFC_CHECK_INVALID_PQ;

        return 0;

    }

    if (BN_num_bits(dsa->params.q) >= BN_num_bits(dsa->params.p)) {

        ERR_raise(ERR_LIB_DSA, DSA_R_BAD_Q_VALUE);

        *ret = FFC_CHECK_INVALID_PQ;

        return 0;

    }

    return 1;

}

int ossl_dsa_check_params(const DSA *dsa, int checktype, int *ret)

{

    if (!dsa_precheck_params(dsa, ret))

        return 0;

    if (checktype == OSSL_KEYMGMT_VALIDATE_QUICK_CHECK)

        return ossl_ffc_params_simple_validate(dsa->libctx, &dsa->params,

                                               FFC_PARAM_TYPE_DSA, ret);

    else

        /*

         * Do full FFC domain params validation according to FIPS-186-4

         *  - always in FIPS_MODULE

         *  - only if possible (i.e., seed is set) in default provider

         */

        return ossl_ffc_params_full_validate(dsa->libctx, &dsa->params,

                                             FFC_PARAM_TYPE_DSA, ret);

}

/*

 * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation.

 */

int ossl_dsa_check_pub_key(const DSA *dsa, const BIGNUM *pub_key, int *ret)

{

    if (!dsa_precheck_params(dsa, ret))

        return 0;

    return ossl_ffc_validate_public_key(&dsa->params, pub_key, ret)

           && *ret == 0;

}

/*

 * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation.

 * To only be used with ephemeral FFC public keys generated using the approved

 * safe-prime groups.

 */

int ossl_dsa_check_pub_key_partial(const DSA *dsa, const BIGNUM *pub_key, int *ret)

{

    if (!dsa_precheck_params(dsa, ret))

        return 0;

    return ossl_ffc_validate_public_key_partial(&dsa->params, pub_key, ret)

           && *ret == 0;

}

int ossl_dsa_check_priv_key(const DSA *dsa, const BIGNUM *priv_key, int *ret)

{

    *ret = 0;

    if (!dsa_precheck_params(dsa, ret))

        return 0;

    return ossl_ffc_validate_private_key(dsa->params.q, priv_key, ret);

}

/*

 * FFC pairwise check from SP800-56A R3.

 *    Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency

 */

int ossl_dsa_check_pairwise(const DSA *dsa)

{

    int ret = 0;

    BN_CTX *ctx = NULL;

    BIGNUM *pub_key = NULL;

    if (!dsa_precheck_params(dsa, &ret))

        return 0;

    if (dsa->params.g == NULL

        || dsa->priv_key == NULL

        || dsa->pub_key == NULL)

        return 0;

    ctx = BN_CTX_new_ex(dsa->libctx);

    if (ctx == NULL)

        goto err;

    pub_key = BN_new();

    if (pub_key == NULL)

        goto err;

    /* recalculate the public key = (g ^ priv) mod p */

    if (!ossl_dsa_generate_public_key(ctx, dsa, dsa->priv_key, pub_key))

        goto err;

    /* check it matches the existing public_key */

    ret = BN_cmp(pub_key, dsa->pub_key) == 0;

err:

    BN_free(pub_key);

    BN_CTX_free(ctx);

    return ret;

}