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