mirror of
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synced 2026-04-15 22:11:17 -04:00
59ebad0b53
The previous IV was actually 12 byte extended to 16 byte using base64. As the encrypted file should be fine with containing binary data as well we can simply remove the encoding like that here.
591 lines
14 KiB
PHP
591 lines
14 KiB
PHP
<?php
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/**
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* @author Björn Schießle <schiessle@owncloud.com>
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* @author Clark Tomlinson <fallen013@gmail.com>
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* @author Joas Schilling <nickvergessen@owncloud.com>
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* @author Lukas Reschke <lukas@owncloud.com>
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* @author Scrutinizer Auto-Fixer <auto-fixer@scrutinizer-ci.com>
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* @author Thomas Müller <thomas.mueller@tmit.eu>
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*
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* @copyright Copyright (c) 2016, ownCloud, Inc.
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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 OCA\Encryption\Crypto;
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use OC\Encryption\Exceptions\DecryptionFailedException;
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use OC\Encryption\Exceptions\EncryptionFailedException;
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use OCA\Encryption\Exceptions\MultiKeyDecryptException;
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use OCA\Encryption\Exceptions\MultiKeyEncryptException;
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use OCP\Encryption\Exceptions\GenericEncryptionException;
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use OCP\IConfig;
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use OCP\ILogger;
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use OCP\IUserSession;
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/**
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* Class Crypt provides the encryption implementation of the default ownCloud
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* encryption module. As default AES-256-CTR is used, it does however offer support
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* for the following modes:
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*
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* - AES-256-CTR
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* - AES-128-CTR
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* - AES-256-CFB
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* - AES-128-CFB
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*
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* @package OCA\Encryption\Crypto
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*/
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class Crypt {
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const DEFAULT_CIPHER = 'AES-256-CTR';
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// default cipher from old ownCloud versions
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const LEGACY_CIPHER = 'AES-128-CFB';
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// default key format, old ownCloud version encrypted the private key directly
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// with the user password
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const LEGACY_KEY_FORMAT = 'password';
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const HEADER_START = 'HBEGIN';
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const HEADER_END = 'HEND';
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/** @var ILogger */
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private $logger;
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/** @var string */
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private $user;
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/** @var IConfig */
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private $config;
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/** @var array */
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private $supportedKeyFormats;
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/** @var array */
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private $supportedCiphersAndKeySize = [
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'AES-256-CTR' => 32,
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'AES-128-CTR' => 16,
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'AES-256-CFB' => 32,
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'AES-128-CFB' => 16,
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];
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/**
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* @param ILogger $logger
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* @param IUserSession $userSession
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* @param IConfig $config
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*/
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public function __construct(ILogger $logger, IUserSession $userSession, IConfig $config) {
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$this->logger = $logger;
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$this->user = $userSession && $userSession->isLoggedIn() ? $userSession->getUser()->getUID() : '"no user given"';
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$this->config = $config;
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$this->supportedKeyFormats = ['hash', 'password'];
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}
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/**
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* create new private/public key-pair for user
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*
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* @return array|bool
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*/
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public function createKeyPair() {
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$log = $this->logger;
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$res = $this->getOpenSSLPKey();
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if (!$res) {
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$log->error("Encryption Library couldn't generate users key-pair for {$this->user}",
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['app' => 'encryption']);
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if (openssl_error_string()) {
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$log->error('Encryption library openssl_pkey_new() fails: ' . openssl_error_string(),
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['app' => 'encryption']);
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}
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} elseif (openssl_pkey_export($res,
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$privateKey,
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null,
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$this->getOpenSSLConfig())) {
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$keyDetails = openssl_pkey_get_details($res);
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$publicKey = $keyDetails['key'];
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return [
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'publicKey' => $publicKey,
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'privateKey' => $privateKey
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];
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}
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$log->error('Encryption library couldn\'t export users private key, please check your servers OpenSSL configuration.' . $this->user,
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['app' => 'encryption']);
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if (openssl_error_string()) {
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$log->error('Encryption Library:' . openssl_error_string(),
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['app' => 'encryption']);
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}
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return false;
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}
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/**
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* Generates a new private key
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*
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* @return resource
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*/
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public function getOpenSSLPKey() {
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$config = $this->getOpenSSLConfig();
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return openssl_pkey_new($config);
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}
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/**
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* get openSSL Config
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*
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* @return array
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*/
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private function getOpenSSLConfig() {
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$config = ['private_key_bits' => 4096];
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$config = array_merge(
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$config,
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$this->config->getSystemValue('openssl', [])
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);
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return $config;
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}
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/**
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* @param string $plainContent
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* @param string $passPhrase
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* @return false|string
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* @throws EncryptionFailedException
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*/
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public function symmetricEncryptFileContent($plainContent, $passPhrase) {
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if (!$plainContent) {
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$this->logger->error('Encryption Library, symmetrical encryption failed no content given',
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['app' => 'encryption']);
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return false;
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}
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$iv = $this->generateIv();
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$encryptedContent = $this->encrypt($plainContent,
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$iv,
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$passPhrase,
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$this->getCipher());
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// combine content to encrypt the IV identifier and actual IV
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$catFile = $this->concatIV($encryptedContent, $iv);
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$padded = $this->addPadding($catFile);
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return $padded;
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}
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/**
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* generate header for encrypted file
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*
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* @param string $keyFormat (can be 'hash' or 'password')
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* @return string
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* @throws \InvalidArgumentException
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*/
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public function generateHeader($keyFormat = 'hash') {
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if (in_array($keyFormat, $this->supportedKeyFormats, true) === false) {
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throw new \InvalidArgumentException('key format "' . $keyFormat . '" is not supported');
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}
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$cipher = $this->getCipher();
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$header = self::HEADER_START
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. ':cipher:' . $cipher
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. ':keyFormat:' . $keyFormat
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. ':' . self::HEADER_END;
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return $header;
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}
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/**
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* @param string $plainContent
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* @param string $iv
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* @param string $passPhrase
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* @param string $cipher
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* @return string
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* @throws EncryptionFailedException
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*/
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private function encrypt($plainContent, $iv, $passPhrase = '', $cipher = self::DEFAULT_CIPHER) {
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$encryptedContent = openssl_encrypt($plainContent,
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$cipher,
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$passPhrase,
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false,
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$iv);
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if (!$encryptedContent) {
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$error = 'Encryption (symmetric) of content failed';
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$this->logger->error($error . openssl_error_string(),
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['app' => 'encryption']);
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throw new EncryptionFailedException($error);
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}
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return $encryptedContent;
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}
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/**
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* return Cipher either from config.php or the default cipher defined in
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* this class
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*
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* @return string
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*/
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public function getCipher() {
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$cipher = $this->config->getSystemValue('cipher', self::DEFAULT_CIPHER);
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if (!isset($this->supportedCiphersAndKeySize[$cipher])) {
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$this->logger->warning(
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sprintf(
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'Unsupported cipher (%s) defined in config.php supported. Falling back to %s',
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$cipher,
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self::DEFAULT_CIPHER
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),
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['app' => 'encryption']);
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$cipher = self::DEFAULT_CIPHER;
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}
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return $cipher;
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}
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/**
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* get key size depending on the cipher
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*
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* @param string $cipher
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* @return int
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* @throws \InvalidArgumentException
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*/
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protected function getKeySize($cipher) {
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if(isset($this->supportedCiphersAndKeySize[$cipher])) {
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return $this->supportedCiphersAndKeySize[$cipher];
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}
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throw new \InvalidArgumentException(
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sprintf(
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'Unsupported cipher (%s) defined.',
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$cipher
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)
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);
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}
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/**
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* get legacy cipher
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*
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* @return string
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*/
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public function getLegacyCipher() {
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return self::LEGACY_CIPHER;
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}
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/**
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* @param string $encryptedContent
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* @param string $iv
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* @return string
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*/
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private function concatIV($encryptedContent, $iv) {
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return $encryptedContent . '00iv00' . $iv;
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}
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/**
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* @param string $data
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* @return string
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*/
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private function addPadding($data) {
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return $data . 'xx';
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}
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/**
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* generate password hash used to encrypt the users private key
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*
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* @param string $password
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* @param string $cipher
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* @param string $uid only used for user keys
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* @return string
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*/
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protected function generatePasswordHash($password, $cipher, $uid = '') {
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$instanceId = $this->config->getSystemValue('instanceid');
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$instanceSecret = $this->config->getSystemValue('secret');
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$salt = hash('sha256', $uid . $instanceId . $instanceSecret, true);
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$keySize = $this->getKeySize($cipher);
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$hash = hash_pbkdf2(
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'sha256',
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$password,
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$salt,
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100000,
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$keySize,
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true
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);
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return $hash;
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}
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/**
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* encrypt private key
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*
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* @param string $privateKey
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* @param string $password
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* @param string $uid for regular users, empty for system keys
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* @return false|string
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*/
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public function encryptPrivateKey($privateKey, $password, $uid = '') {
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$cipher = $this->getCipher();
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$hash = $this->generatePasswordHash($password, $cipher, $uid);
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$encryptedKey = $this->symmetricEncryptFileContent(
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$privateKey,
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$hash
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);
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return $encryptedKey;
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}
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/**
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* @param string $privateKey
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* @param string $password
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* @param string $uid for regular users, empty for system keys
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* @return false|string
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*/
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public function decryptPrivateKey($privateKey, $password = '', $uid = '') {
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$header = $this->parseHeader($privateKey);
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if (isset($header['cipher'])) {
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$cipher = $header['cipher'];
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} else {
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$cipher = self::LEGACY_CIPHER;
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}
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if (isset($header['keyFormat'])) {
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$keyFormat = $header['keyFormat'];
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} else {
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$keyFormat = self::LEGACY_KEY_FORMAT;
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}
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if ($keyFormat === 'hash') {
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$password = $this->generatePasswordHash($password, $cipher, $uid);
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}
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// If we found a header we need to remove it from the key we want to decrypt
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if (!empty($header)) {
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$privateKey = substr($privateKey,
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strpos($privateKey,
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self::HEADER_END) + strlen(self::HEADER_END));
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}
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$plainKey = $this->symmetricDecryptFileContent($privateKey,
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$password,
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$cipher);
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if ($this->isValidPrivateKey($plainKey) === false) {
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return false;
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}
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return $plainKey;
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}
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/**
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* check if it is a valid private key
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*
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* @param string $plainKey
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* @return bool
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*/
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protected function isValidPrivateKey($plainKey) {
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$res = openssl_get_privatekey($plainKey);
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if (is_resource($res)) {
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$sslInfo = openssl_pkey_get_details($res);
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if (isset($sslInfo['key'])) {
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return true;
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}
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}
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return false;
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}
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/**
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* @param string $keyFileContents
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* @param string $passPhrase
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* @param string $cipher
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* @return string
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* @throws DecryptionFailedException
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*/
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public function symmetricDecryptFileContent($keyFileContents, $passPhrase, $cipher = self::DEFAULT_CIPHER) {
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// Remove Padding
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$noPadding = $this->removePadding($keyFileContents);
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$catFile = $this->splitIv($noPadding);
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return $this->decrypt($catFile['encrypted'],
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$catFile['iv'],
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$passPhrase,
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$cipher);
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}
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/**
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* remove padding
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*
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* @param $padded
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* @return string|false
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*/
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private function removePadding($padded) {
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if (substr($padded, -2) === 'xx') {
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return substr($padded, 0, -2);
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}
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return false;
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}
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/**
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* split iv from encrypted content
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*
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* @param string|false $catFile
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* @return string
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*/
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private function splitIv($catFile) {
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// Fetch encryption metadata from end of file
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$meta = substr($catFile, -22);
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// Fetch IV from end of file
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$iv = substr($meta, -16);
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// Remove IV and IV Identifier text to expose encrypted content
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$encrypted = substr($catFile, 0, -22);
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return [
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'encrypted' => $encrypted,
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'iv' => $iv
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];
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}
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/**
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* @param string $encryptedContent
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* @param string $iv
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* @param string $passPhrase
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* @param string $cipher
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* @return string
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* @throws DecryptionFailedException
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*/
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private function decrypt($encryptedContent, $iv, $passPhrase = '', $cipher = self::DEFAULT_CIPHER) {
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$plainContent = openssl_decrypt($encryptedContent,
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$cipher,
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$passPhrase,
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false,
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$iv);
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if ($plainContent) {
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return $plainContent;
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} else {
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throw new DecryptionFailedException('Encryption library: Decryption (symmetric) of content failed: ' . openssl_error_string());
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}
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}
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/**
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* @param string $data
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* @return array
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*/
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protected function parseHeader($data) {
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$result = [];
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if (substr($data, 0, strlen(self::HEADER_START)) === self::HEADER_START) {
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$endAt = strpos($data, self::HEADER_END);
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$header = substr($data, 0, $endAt + strlen(self::HEADER_END));
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// +1 not to start with an ':' which would result in empty element at the beginning
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$exploded = explode(':',
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substr($header, strlen(self::HEADER_START) + 1));
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$element = array_shift($exploded);
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while ($element != self::HEADER_END) {
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$result[$element] = array_shift($exploded);
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$element = array_shift($exploded);
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}
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}
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return $result;
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}
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/**
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* generate initialization vector
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*
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* @return string
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* @throws GenericEncryptionException
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*/
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private function generateIv() {
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return random_bytes(16);
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}
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/**
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* Generate a cryptographically secure pseudo-random base64 encoded 256-bit
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* ASCII key, used as file key
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*
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* @return string
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* @throws \Exception
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*/
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public function generateFileKey() {
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// Generate key
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$key = base64_encode(openssl_random_pseudo_bytes(32, $strong));
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if (!$key || !$strong) {
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// If OpenSSL indicates randomness is insecure, log error
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throw new \Exception('Encryption library, Insecure symmetric key was generated using openssl_random_pseudo_bytes()');
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}
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return $key;
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}
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/**
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* @param $encKeyFile
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* @param $shareKey
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* @param $privateKey
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* @return string
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* @throws MultiKeyDecryptException
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*/
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public function multiKeyDecrypt($encKeyFile, $shareKey, $privateKey) {
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if (!$encKeyFile) {
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throw new MultiKeyDecryptException('Cannot multikey decrypt empty plain content');
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}
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if (openssl_open($encKeyFile, $plainContent, $shareKey, $privateKey)) {
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return $plainContent;
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} else {
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throw new MultiKeyDecryptException('multikeydecrypt with share key failed:' . openssl_error_string());
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}
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}
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/**
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* @param string $plainContent
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* @param array $keyFiles
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* @return array
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* @throws MultiKeyEncryptException
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*/
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public function multiKeyEncrypt($plainContent, array $keyFiles) {
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// openssl_seal returns false without errors if plaincontent is empty
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// so trigger our own error
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if (empty($plainContent)) {
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throw new MultiKeyEncryptException('Cannot multikeyencrypt empty plain content');
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}
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// Set empty vars to be set by openssl by reference
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$sealed = '';
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$shareKeys = [];
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$mappedShareKeys = [];
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if (openssl_seal($plainContent, $sealed, $shareKeys, $keyFiles)) {
|
|
$i = 0;
|
|
|
|
// Ensure each shareKey is labelled with its corresponding key id
|
|
foreach ($keyFiles as $userId => $publicKey) {
|
|
$mappedShareKeys[$userId] = $shareKeys[$i];
|
|
$i++;
|
|
}
|
|
|
|
return [
|
|
'keys' => $mappedShareKeys,
|
|
'data' => $sealed
|
|
];
|
|
} else {
|
|
throw new MultiKeyEncryptException('multikeyencryption failed ' . openssl_error_string());
|
|
}
|
|
}
|
|
}
|
|
|