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<?php
declare(strict_types=1);
/**
* SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
* SPDX-FileCopyrightText: 2016 ownCloud, Inc.
* SPDX-License-Identifier: AGPL-3.0-only
*/
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 {
private string $encryptedValue = '';
/**
* @param string $value Value of the token. Can be encrypted or not encrypted.
*/
public function __construct(
private string $value,
) {
}
/**
* Encrypted value of the token. This is used to mitigate BREACH alike
* vulnerabilities. For display measures do use this functionality.
*/
public function getEncryptedValue(): string {
if ($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.
*/
public function getDecryptedValue(): string {
$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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