algorithms_rsa_verify.c

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/*
 * algorithms_rsa_verify.c
 *
 *  Created on: 28-07-2015
 *      Author: franchoco
 */

#include <gmp.h>
#include <stdlib.h>

#include "tc.h"
#include "tc_internal.h"

int tc_rsa_verify(bytes_t * signature, bytes_t * doc, key_metainfo_t * info, tc_hash_type_t hashtype) {

    bytes_t * doc_pkcs1 = tc_prepare_document(doc, hashtype, info);

    mpz_t c, x, e, n, new_x;
    mpz_inits(c, x, e, n, new_x, NULL);
    TC_BYTES_TO_MPZ(x, doc_pkcs1);
    TC_BYTES_TO_MPZ(c, signature);
    TC_BYTES_TO_MPZ(e, info->public_key->e);
    TC_BYTES_TO_MPZ(n, info->public_key->n);

    mpz_powm(new_x, c, e, n);
    int cmp = mpz_cmp(x, new_x);

    tc_clear_bytes(doc_pkcs1);
    mpz_clears(c, x, e, n, new_x, NULL);

    return cmp == 0;
}