[SECURITY] keep up with modern password hashing standards

3 files changed, 79 insertions, 18 deletions

diff --git a/inc/config.php b/inc/config.php
index d5bdbfe5..c0e967af 100644
--- a/inc/config.php
+++ b/inc/config.php
@@ -1672,3 +1672,18 @@
 		'<a href="https://youtu.be/$2" target="_blank" class="file">'.
 		'<img style="width:360px;height:270px;" src="//img.youtube.com/vi/$2/0.jpg" class="post-image"/>'.
 		'</a></div>';
+
+	// Password hashing function
+	//
+	// $5$ <- SHA256
+	// $6$ <- SHA512
+	//
+	// 25000 rounds make for ~0.05s on my 2015 Core i3 computer.
+	//
+	// https://secure.php.net/manual/en/function.crypt.php
+	$config['password_crypt'] = '$6$rounds=25000$';
+
+	// Password hashing method version
+	// If set to 0, it won't upgrade hashes using old password encryption schema, only create new.
+	// You can set it to a higher value, to further migrate to other password hashing function.
+	$config['password_crypt_version'] = 1;
diff --git a/inc/mod/auth.php b/inc/mod/auth.php
index 01ed5b68..fa1a0f4f 100644
--- a/inc/mod/auth.php
+++ b/inc/mod/auth.php
@@ -18,7 +18,18 @@ function mkhash($username, $password, $salt = false) {
 	}
 	
 	// generate hash (method is not important as long as it's strong)
-	$hash = substr(base64_encode(md5($username . $config['cookies']['salt'] . sha1($username . $password . $salt . ($config['mod']['lock_ip'] ? $_SERVER['REMOTE_ADDR'] : ''), true), true)), 0, 20);
+	$hash = substr(
+		base64_encode(
+			md5(
+				$username . $config['cookies']['salt'] . sha1(
+					$username . $password . $salt . (
+						$config['mod']['lock_ip'] ? $_SERVER['REMOTE_ADDR'] : ''
+					), true
+				) . sha1($config['password_crypt_version']) // Log out users being logged in with older password encryption schema
+				, true
+			)
+		), 0, 20
+	);
 	
 	if (isset($generated_salt))
 		return array($hash, $salt);
@@ -26,25 +37,63 @@ function mkhash($username, $password, $salt = false) {
 		return $hash;
 }
 
-function generate_salt() {
-	mt_srand(microtime(true) * 100000 + memory_get_usage(true));
-	return md5(uniqid(mt_rand(), true));
+function crypt_password_old($password) {
+	$salt = generate_salt();
+	$password = hash('sha256', $salt . sha1($password));
+	return array($salt, $password);
 }
 
-function login($username, $password, $makehash=true) {
-	global $mod;
-	
-	// SHA1 password
-	if ($makehash) {
-		$password = sha1($password);
+function crypt_password($password) {
+	global $config;
+	// `salt` database field is reused as a version value. We don't want it to be 0.
+	$version = $config['password_crypt_version'] ? $config['password_crypt_version'] : 1;
+	$new_salt = generate_salt();
+	$password = crypt($password, $config['password_crypt'] . $new_salt . "$");
+	return array($version, $password);
+}
+
+function test_password($password, $salt, $test) {
+	global $config;
+
+	// Version = 0 denotes an old password hashing schema. In the same column, the
+	// password hash was kept previously
+	$version = (strlen($salt) <= 8) ? (int) $salt : 0;
+
+	if ($version == 0) {
+		$comp = hash('sha256', $salt . sha1($test));
 	}
+	else {
+		$comp = crypt($test, $password);
+	}
+	return array($version, hash_equals($password, $comp));
+}
+
+function generate_salt() {
+	// 128 bits of entropy
+	return strtr(base64_encode(mcrypt_create_iv(16, MCRYPT_DEV_URANDOM)), '+', '.');
+}
+
+function login($username, $password) {
+	global $mod, $config;
 	
 	$query = prepare("SELECT `id`, `type`, `boards`, `password`, `salt` FROM ``mods`` WHERE `username` = :username");
 	$query->bindValue(':username', $username);
 	$query->execute() or error(db_error($query));
 	
 	if ($user = $query->fetch(PDO::FETCH_ASSOC)) {
-		if ($user['password'] === hash('sha256', $user['salt'] . $password)) {
+		list($version, $ok) = test_password($user['password'], $user['salt'], $password);
+
+		if ($ok) {
+			if ($config['password_crypt_version'] > $version) {
+				// It's time to upgrade the password hashing method!
+				list ($user['salt'], $user['password']) = crypt_password($password);
+				$query = prepare("UPDATE ``mods`` SET `password` = :password, `salt` = :salt WHERE `id` = :id");
+				$query->bindValue(':password', $user['password']);
+				$query->bindValue(':salt', $user['salt']);
+				$query->bindValue(':id', $user['id']);
+				$query->execute() or error(db_error($query));
+			}
+
 			return $mod = array(
 				'id' => $user['id'],
 				'type' => $user['type'],
diff --git a/inc/mod/pages.php b/inc/mod/pages.php
index 2c679b20..a07de4c7 100644
--- a/inc/mod/pages.php
+++ b/inc/mod/pages.php
@@ -1734,9 +1734,8 @@ function mod_user($uid) {
 		}
 		
 		if ($_POST['password'] != '') {
-			$salt = generate_salt();
-			$password = hash('sha256', $salt . sha1($_POST['password']));
-			
+			list($salt, $password) = crypt_password($_POST['password']);
+
 			$query = prepare('UPDATE ``mods`` SET `password` = :password, `salt` = :salt WHERE `id` = :id');
 			$query->bindValue(':id', $uid);
 			$query->bindValue(':password', $password);
@@ -1761,8 +1760,7 @@ function mod_user($uid) {
 	
 	if (hasPermission($config['mod']['change_password']) && $uid == $mod['id'] && isset($_POST['password'])) {
 		if ($_POST['password'] != '') {
-			$salt = generate_salt();
-			$password = hash('sha256', $salt . sha1($_POST['password']));
+			list($salt, $password) = crypt_password($_POST['password']);
 
 			$query = prepare('UPDATE ``mods`` SET `password` = :password, `salt` = :salt WHERE `id` = :id');
 			$query->bindValue(':id', $uid);
@@ -1834,8 +1832,7 @@ function mod_user_new() {
 		if (!isset($config['mod']['groups'][$type]) || $type == DISABLED)
 			error(sprintf($config['error']['invalidfield'], 'type'));
 		
-		$salt = generate_salt();
-		$password = hash('sha256', $salt . sha1($_POST['password']));
+		list($salt, $password) = crypt_password($_POST['password']);
 		
 		$query = prepare('INSERT INTO ``mods`` VALUES (NULL, :username, :password, :salt, :type, :boards)');
 		$query->bindValue(':username', $_POST['username']);