proxmark3/client/crypto/asn1utils.c

//-----------------------------------------------------------------------------
// Copyright (C) 2018 Merlok
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// asn.1 utils
//-----------------------------------------------------------------------------

#include "asn1utils.h"
#include <mbedtls/asn1.h>

int ecdsa_asn1_get_signature(uint8_t *signature, size_t signaturelen, uint8_t *rval, uint8_t *sval) {
	if (!signature || !signaturelen || !rval || !sval)
		return 1;

	int res = 0;
	unsigned char *p = signature;
	const unsigned char *end = p + signaturelen;
	size_t len;
	mbedtls_mpi xmpi;

	if ((res = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) == 0) {
		mbedtls_mpi_init(&xmpi);
		res = mbedtls_asn1_get_mpi(&p, end, &xmpi);
		if (res) {
			mbedtls_mpi_free(&xmpi);
			goto exit;
		}
		
		res = mbedtls_mpi_write_binary(&xmpi, rval, 32);
		mbedtls_mpi_free(&xmpi);
		if (res) 
			goto exit;

		mbedtls_mpi_init(&xmpi);
		res = mbedtls_asn1_get_mpi(&p, end, &xmpi);
		if (res) {
			mbedtls_mpi_free(&xmpi);
			goto exit;
		}
		
		res = mbedtls_mpi_write_binary(&xmpi, sval, 32);
		mbedtls_mpi_free(&xmpi);
		if (res) 
			goto exit;

		// check size
		if (end != p)
			return 2;
		}

exit:
	return res;
}

int asn1_print(uint8_t *asn1buf, size_t asn1buflen, char *indent) {
	
	return 0;
}