PHP Decode

<?php
/**
 * Copyright 2010-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 * http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

namespace Aws\Common\Signature;

use Aws\Common\Credentials\CredentialsInterface;
use Aws\Common\Enum\DateFormat;
use Guzzle\Http\Message\RequestInterface;

/**
 * Implementation of Signature Version 3 HTTPS
 * @link http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/RESTAuthentication.html
 */
class SignatureV3Https extends AbstractSignature
{
    public function signRequest(RequestInterface $request, CredentialsInterface $credentials)
    {
        // Add a date header if one is not set
        if (!$request->hasHeader('date') && !$request->hasHeader('x-amz-date')) {
            $request->setHeader('Date', gmdate(DateFormat::RFC1123, $this->getTimestamp()));
        }

        // Add the security token if one is present
        if ($credentials->getSecurityToken()) {
            $request->setHeader('x-amz-security-token', $credentials->getSecurityToken());
        }

        // Determine the string to sign
        $stringToSign = (string) ($request->getHeader('Date') ?: $request->getHeader('x-amz-date'));
        $request->getParams()->set('aws.string_to_sign', $stringToSign);

        // Calculate the signature
        $signature = base64_encode(hash_hmac('sha256', $stringToSign, $credentials->getSecretKey(), true));

        // Add the authorization header to the request
        $headerFormat = 'AWS3-HTTPS AWSAccessKeyId=%s,Algorithm=HmacSHA256,Signature=%s';
        $request->setHeader('X-Amzn-Authorization', sprintf($headerFormat, $credentials->getAccessKeyId(), $signature));
    }
}
 ?>