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142 lines
4.3 KiB
142 lines
4.3 KiB
<?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 Andreas Fischer <bantu@owncloud.com> |
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* @author Lukas Reschke <lukas@statuscode.ch> |
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* @author Morris Jobke <hey@morrisjobke.de> |
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* @author Roeland Jago Douma <roeland@famdouma.nl> |
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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; |
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use phpseclib\Crypt\AES; |
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use phpseclib\Crypt\Hash; |
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use OCP\Security\ICrypto; |
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use OCP\Security\ISecureRandom; |
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use OCP\IConfig; |
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/** |
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* Class Crypto provides a high-level encryption layer using AES-CBC. If no key has been provided |
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* it will use the secret defined in config.php as key. Additionally the message will be HMAC'd. |
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* |
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* Usage: |
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* $encryptWithDefaultPassword = \OC::$server->getCrypto()->encrypt('EncryptedText'); |
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* $encryptWithCustompassword = \OC::$server->getCrypto()->encrypt('EncryptedText', 'password'); |
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* |
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* @package OC\Security |
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*/ |
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class Crypto implements ICrypto { |
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/** @var AES $cipher */ |
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private $cipher; |
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/** @var int */ |
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private $ivLength = 16; |
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/** @var IConfig */ |
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private $config; |
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/** @var ISecureRandom */ |
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private $random; |
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/** |
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* @param IConfig $config |
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* @param ISecureRandom $random |
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*/ |
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public function __construct(IConfig $config, ISecureRandom $random) { |
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$this->cipher = new AES(); |
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$this->config = $config; |
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$this->random = $random; |
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} |
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/** |
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* @param string $message The message to authenticate |
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* @param string $password Password to use (defaults to `secret` in config.php) |
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* @return string Calculated HMAC |
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*/ |
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public function calculateHMAC(string $message, string $password = ''): string { |
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if($password === '') { |
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$password = $this->config->getSystemValue('secret'); |
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} |
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// Append an "a" behind the password and hash it to prevent reusing the same password as for encryption |
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$password = hash('sha512', $password . 'a'); |
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$hash = new Hash('sha512'); |
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$hash->setKey($password); |
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return $hash->hash($message); |
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} |
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/** |
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* Encrypts a value and adds an HMAC (Encrypt-Then-MAC) |
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* @param string $plaintext |
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* @param string $password Password to encrypt, if not specified the secret from config.php will be taken |
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* @return string Authenticated ciphertext |
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*/ |
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public function encrypt(string $plaintext, string $password = ''): string { |
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if($password === '') { |
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$password = $this->config->getSystemValue('secret'); |
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} |
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$this->cipher->setPassword($password); |
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$iv = $this->random->generate($this->ivLength); |
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$this->cipher->setIV($iv); |
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$ciphertext = bin2hex($this->cipher->encrypt($plaintext)); |
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$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, $password)); |
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return $ciphertext.'|'.$iv.'|'.$hmac; |
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} |
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/** |
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* Decrypts a value and verifies the HMAC (Encrypt-Then-Mac) |
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* @param string $authenticatedCiphertext |
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* @param string $password Password to encrypt, if not specified the secret from config.php will be taken |
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* @return string plaintext |
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* @throws \Exception If the HMAC does not match |
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* @throws \Exception If the decryption failed |
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*/ |
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public function decrypt(string $authenticatedCiphertext, string $password = ''): string { |
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if ($password === '') { |
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$password = $this->config->getSystemValue('secret'); |
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} |
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$this->cipher->setPassword($password); |
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$parts = explode('|', $authenticatedCiphertext); |
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if (\count($parts) !== 3) { |
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throw new \Exception('Authenticated ciphertext could not be decoded.'); |
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} |
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$ciphertext = hex2bin($parts[0]); |
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$iv = $parts[1]; |
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$hmac = hex2bin($parts[2]); |
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$this->cipher->setIV($iv); |
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if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $password), $hmac)) { |
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throw new \Exception('HMAC does not match.'); |
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} |
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$result = $this->cipher->decrypt($ciphertext); |
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if ($result === false) { |
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throw new \Exception('Decryption failed'); |
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} |
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return $result; |
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} |
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}
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