Backport \OC\Security\Crypto to ownCloud 7

Conflicts:
	lib/repair/repairconfig.php

2 files changed, 176 insertions, 0 deletions

diff --git a/lib/private/security/crypto.php b/lib/private/security/crypto.php
new file mode 100644
index 00000000000..44fe2fc0326
--- /dev/null
+++ b/lib/private/security/crypto.php
@@ -0,0 +1,130 @@
+<?php
+/**
+ * Copyright (c) 2014 Lukas Reschke <lukas@owncloud.com>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+
+namespace OC\Security;
+
+use Crypt_AES;
+use Crypt_Hash;
+use OCP\Security\ICrypto;
+use OCP\Security\StringUtils;
+use OCP\IConfig;
+
+/**
+ * Class Crypto provides a high-level encryption layer using AES-CBC. If no key has been provided
+ * it will use the secret defined in config.php as key. Additionally the message will be HMAC'd.
+ *
+ * Usage:
+ * $encryptWithDefaultPassword = \OC::$server->getCrypto()->encrypt('EncryptedText');
+ * $encryptWithCustompassword = \OC::$server->getCrypto()->encrypt('EncryptedText', 'password');
+ *
+ * @package OC\Security
+ */
+class Crypto implements ICrypto {
+	/** @var Crypt_AES $cipher */
+	private $cipher;
+	/** @var int */
+	private $ivLength = 16;
+	/** @var IConfig */
+	private $config;
+
+	/**
+	 * @param IConfig $config
+	 */
+	function __construct(IConfig $config) {
+		$this->cipher = new Crypt_AES();
+		$this->config = $config;
+	}
+
+	/**
+	 * Custom implementation of hex2bin since the function is only available starting
+	 * with PHP 5.4
+	 *
+	 * @TODO Remove this once 5.3 support for ownCloud is dropped
+	 * @param $message
+	 * @return string
+	 */
+	protected static function hexToBin($message) {
+		if (function_exists('hex2bin')) {
+			return hex2bin($message);
+		}
+
+		return pack("H*", $message);
+	}
+
+	/**
+	 * @param string $message The message to authenticate
+	 * @param string $password Password to use (defaults to `secret` in config.php)
+	 * @return string Calculated HMAC
+	 */
+	public function calculateHMAC($message, $password = '') {
+		if($password === '') {
+			$password = $this->config->getSystemValue('secret');
+		}
+
+		// Append an "a" behind the password and hash it to prevent reusing the same password as for encryption
+		$password = hash('sha512', $password . 'a');
+
+		$hash = new Crypt_Hash('sha512');
+		$hash->setKey($password);
+		return $hash->hash($message);
+	}
+
+	/**
+	 * Encrypts a value and adds an HMAC (Encrypt-Then-MAC)
+	 * @param string $plaintext
+	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
+	 * @return string Authenticated ciphertext
+	 */
+	public function encrypt($plaintext, $password = '') {
+		if($password === '') {
+			$password = $this->config->getSystemValue('secret');
+		}
+		$this->cipher->setPassword($password);
+
+		$iv = \OC_Util::generateRandomBytes($this->ivLength);
+		$this->cipher->setIV($iv);
+
+		$ciphertext = bin2hex($this->cipher->encrypt($plaintext));
+		$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, $password));
+
+		return $ciphertext.'|'.$iv.'|'.$hmac;
+	}
+
+	/**
+	 * Decrypts a value and verifies the HMAC (Encrypt-Then-Mac)
+	 * @param string $authenticatedCiphertext
+	 * @param string $password Password to encrypt, if not specified the secret from config.php will be taken
+	 * @return string plaintext
+	 * @throws \Exception If the HMAC does not match
+	 */
+	public function decrypt($authenticatedCiphertext, $password = '') {
+		if($password === '') {
+			$password = $this->config->getSystemValue('secret');
+		}
+		$this->cipher->setPassword($password);
+
+		$parts = explode('|', $authenticatedCiphertext);
+		if(sizeof($parts) !== 3) {
+			throw new \Exception('Authenticated ciphertext could not be decoded.');
+		}
+
+		$ciphertext = self::hexToBin($parts[0]);
+		$iv = $parts[1];
+		$hmac = self::hexToBin($parts[2]);
+
+		$this->cipher->setIV($iv);
+
+		if(!StringUtils::equals($this->calculateHMAC($parts[0].$parts[1], $password), $hmac)) {
+			throw new \Exception('HMAC does not match.');
+		}
+
+		return $this->cipher->decrypt($ciphertext);
+	}
+
+}
\ No newline at end of file
diff --git a/lib/private/security/stringutils.php b/lib/private/security/stringutils.php
new file mode 100644
index 00000000000..449883b634f
--- /dev/null
+++ b/lib/private/security/stringutils.php
@@ -0,0 +1,46 @@
+<?php
+/**
+ * Copyright (c) 2014 Lukas Reschke <lukas@owncloud.com>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+namespace OC\Security;
+
+class StringUtils {
+
+	/**
+	 * Compares whether two strings are equal. To prevent guessing of the string
+	 * length this is done by comparing two hashes against each other and afterwards
+	 * a comparison of the real string to prevent against the unlikely chance of
+	 * collisions.
+	 *
+	 * Be aware that this function may leak whether the string to compare have a different
+	 * length.
+	 *
+	 * @param string $expected The expected value
+	 * @param string $input The input to compare against
+	 * @return bool True if the two strings are equal, otherwise false.
+	 */
+	public static function equals($expected, $input) {
+
+		if(!is_string($expected) || !is_string($input)) {
+			return false;
+		}
+
+		if(function_exists('hash_equals')) {
+			return hash_equals($expected, $input);
+		}
+
+		$randomString = \OC_Util::generateRandomBytes(10);
+
+		if(hash('sha512', $expected.$randomString) === hash('sha512', $input.$randomString)) {
+			if($expected === $input) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+}
\ No newline at end of file