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<?php
/**
* @copyright Copyright (c) 2016, ownCloud, Inc.
*
* @author Lukas Reschke <lukas@statuscode.ch>
*
* @license AGPL-3.0
*
* This code is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License, version 3,
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
namespace OC\Security\CSRF;
/**
* Class CsrfToken represents the stored or provided CSRF token. To mitigate
* BREACH alike vulnerabilities the token is returned in an encrypted value as
* well in an unencrypted value. For display measures to the user always the
* unencrypted one should be chosen.
*
* @package OC\Security\CSRF
*/
class CsrfToken {
/** @var string */
private $value;
/** @var string */
private $encryptedValue = '';
/**
* @param string $value Value of the token. Can be encrypted or not encrypted.
*/
public function __construct($value) {
$this->value = $value;
}
/**
* Encrypted value of the token. This is used to mitigate BREACH alike
* vulnerabilities. For display measures do use this functionality.
*
* @return string
*/
public function getEncryptedValue() {
if($this->encryptedValue === '') {
$sharedSecret = random_bytes(strlen($this->value));
$this->encryptedValue = base64_encode($this->value ^ $sharedSecret) . ':' . base64_encode($sharedSecret);
}
return $this->encryptedValue;
}
/**
* The unencrypted value of the token. Used for decrypting an already
* encrypted token.
*
* @return string
*/
public function getDecryptedValue() {
$token = explode(':', $this->value);
if (count($token) !== 2) {
return '';
}
$obfuscatedToken = $token[0];
$secret = $token[1];
return base64_decode($obfuscatedToken) ^ base64_decode($secret);
}
}
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