From 24ca2d858f9cc020b2ca7310977cd4272a6809fb Mon Sep 17 00:00:00 2001
From: Lukas Reschke <lukas@owncloud.com>
Date: Tue, 4 Nov 2014 16:05:31 +0100
Subject: Add OCP\Security\IHasher

Public interface for hashing which also works with legacy ownCloud hashes and supports updating the legacy hash via a passed reference.

Follow-up of https://github.com/owncloud/core/pull/10219#issuecomment-61624662
Requires https://github.com/owncloud/3rdparty/pull/136
---
 lib/private/security/hasher.php | 146 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 lib/private/security/hasher.php

(limited to 'lib/private/security')

diff --git a/lib/private/security/hasher.php b/lib/private/security/hasher.php
new file mode 100644
index 00000000000..647e1a307ea
--- /dev/null
+++ b/lib/private/security/hasher.php
@@ -0,0 +1,146 @@
+<?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 OCP\IConfig;
+use OCP\Security\IHasher;
+
+/**
+ * Class Hasher provides some basic hashing functions. Furthermore, it supports legacy hashes
+ * used by previous versions of ownCloud and helps migrating those hashes to newer ones.
+ *
+ * The hashes generated by this class are prefixed (version|hash) with a version parameter to allow possible
+ * updates in the future.
+ * Possible versions:
+ * 	- 1 (Initial version)
+ *
+ * Usage:
+ * // Hashing a message
+ * $hash = \OC::$server->getHasher()->hash('MessageToHash');
+ * // Verifying a message - $newHash will contain the newly calculated hash
+ * $newHash = null;
+ * var_dump(\OC::$server->getHasher()->verify('a', '86f7e437faa5a7fce15d1ddcb9eaeaea377667b8', $newHash));
+ * var_dump($newHash);
+ *
+ * @package OC\Security
+ */
+class Hasher implements IHasher {
+	/** @var IConfig */
+	private $config;
+	/** @var array Options passed to password_hash and password_needs_rehash */
+	private $options = array();
+	/** @var string Salt used for legacy passwords */
+	private $legacySalt = null;
+	/** @var int Current version of the generated hash */
+	private $currentVersion = 1;
+
+	/**
+	 * @param IConfig $config
+	 */
+	function __construct(IConfig $config) {
+		$this->config = $config;
+
+		$hashingCost = $this->config->getSystemValue('hashingCost', null);
+		if(!is_null($hashingCost)) {
+			$this->options['cost'] = $hashingCost;
+		}
+	}
+
+	/**
+	 * Hashes a message using PHP's `password_hash` functionality.
+	 * Please note that the size of the returned string is not guaranteed
+	 * and can be up to 255 characters.
+	 *
+	 * @param string $message Message to generate hash from
+	 * @return string Hash of the message with appended version parameter
+	 */
+	public function hash($message) {
+		return $this->currentVersion . '|' . password_hash($message, PASSWORD_DEFAULT, $this->options);
+	}
+
+	/**
+	 * Get the version and hash from a prefixedHash
+	 * @param string $prefixedHash
+	 * @return null|array Null if the hash is not prefixed, otherwise array('version' => 1, 'hash' => 'foo')
+	 */
+	protected function splitHash($prefixedHash) {
+		$explodedString = explode('|', $prefixedHash, 2);
+		if(sizeof($explodedString) === 2) {
+			if((int)$explodedString[0] > 0) {
+				return array('version' => (int)$explodedString[0], 'hash' => $explodedString[1]);
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * Verify legacy hashes
+	 * @param string $message Message to verify
+	 * @param string $hash Assumed hash of the message
+	 * @param null|string &$newHash Reference will contain the updated hash
+	 * @return bool Whether $hash is a valid hash of $message
+	 */
+	protected function legacyHashVerify($message, $hash, &$newHash = null) {
+		if(empty($this->legacySalt)) {
+			$this->legacySalt = $this->config->getSystemValue('passwordsalt', '');
+		}
+
+		// Verify whether it matches a legacy PHPass or SHA1 string
+		$hashLength = strlen($hash);
+		if($hashLength === 60 && password_verify($message.$this->legacySalt, $hash) ||
+			$hashLength === 40 && StringUtils::equals($hash, sha1($message))) {
+			$newHash = $this->hash($message);
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Verify V1 hashes
+	 * @param string $message Message to verify
+	 * @param string $hash Assumed hash of the message
+	 * @param null|string &$newHash Reference will contain the updated hash if necessary. Update the existing hash with this one.
+	 * @return bool Whether $hash is a valid hash of $message
+	 */
+	protected function verifyHashV1($message, $hash, &$newHash = null) {
+		if(password_verify($message, $hash)) {
+			if(password_needs_rehash($hash, PASSWORD_DEFAULT, $this->options)) {
+				$newHash = $this->hash($message);
+			}
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * @param string $message Message to verify
+	 * @param string $hash Assumed hash of the message
+	 * @param null|string &$newHash Reference will contain the updated hash if necessary. Update the existing hash with this one.
+	 * @return bool Whether $hash is a valid hash of $message
+	 */
+	public function verify($message, $hash, &$newHash = null) {
+		$splittedHash = $this->splitHash($hash);
+
+		if(isset($splittedHash['version'])) {
+			switch ($splittedHash['version']) {
+				case 1:
+					return $this->verifyHashV1($message, $splittedHash['hash'], $newHash);
+			}
+		} else {
+			return $this->legacyHashVerify($message, $hash, $newHash);
+		}
+
+
+		return false;
+	}
+
+}
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