<?php
// vim: foldmethod=marker
/**
 * The MIT License
 *
 * Copyright (c) 2007 Andy Smith
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files ( the "Software" ), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

namespace MediaWiki\Extension\OAuth\Lib;

/**
 * The RSA-SHA1 signature method uses the RSASSA-PKCS1-v1_5 signature algorithm as defined in
 * [RFC3447] section 8.2 ( more simply known as PKCS#1 ), using SHA-1 as the hash function for
 * EMSA-PKCS1-v1_5. It is assumed that the Consumer has provided its RSA public key in a
 * verified way to the Service Provider, in a manner which is beyond the scope of this
 * specification.
 *     - Chapter 9.3 ( "RSA-SHA1" )
 */
abstract class OAuthSignatureMethodRsaSha1 extends OAuthSignatureMethod {
	public function get_name() {
		return "RSA-SHA1";
	}

	// Up to the SP to implement this lookup of keys. Possible ideas are:
	// ( 1 ) do a lookup in a table of trusted certs keyed off of consumer
	// ( 2 ) fetch via http using a url provided by the requester
	// ( 3 ) some sort of specific discovery code based on request
	//
	// Either way should return a string representation of the certificate
	protected abstract function fetch_public_cert( &$request );

	// Up to the SP to implement this lookup of keys. Possible ideas are:
	// ( 1 ) do a lookup in a table of trusted certs keyed off of consumer
	//
	// Either way should return a string representation of the certificate
	protected abstract function fetch_private_cert( &$request );

	public function build_signature( $request, $consumer, $token ) {
		$base_string = $request->get_signature_base_string();
		$request->base_string = $base_string;

		// Fetch the private key cert based on the request
		$cert = $this->fetch_private_cert( $request );

		// Pull the private key ID from the certificate
		$privatekeyid = openssl_get_privatekey( $cert );

		// Sign using the key
		$ok = openssl_sign( $base_string, $signature, $privatekeyid );

		return base64_encode( $signature );
	}

	public function check_signature( $request, $consumer, $token, $signature ) {
		$decoded_sig = base64_decode( $signature );

		$base_string = $request->get_signature_base_string();

		// Fetch the public key cert based on the request
		$cert = $this->fetch_public_cert( $request );

		// Pull the public key ID from the certificate
		$publickeyid = openssl_get_publickey( $cert );

		// Check the computed signature against the one passed in the query
		$ok = openssl_verify( $base_string, $decoded_sig, $publickeyid );

		return $ok == 1;
	}
}