diff --git a/boot.php b/boot.php
index 4d2eac35a..eb3d4e973 100644
--- a/boot.php
+++ b/boot.php
@@ -41,7 +41,7 @@ define('FRIENDICA_PLATFORM',     'Friendica');
 define('FRIENDICA_CODENAME',     'Asparagus');
 define('FRIENDICA_VERSION',      '3.6-dev');
 define('DFRN_PROTOCOL_VERSION',  '2.23');
-define('DB_UPDATE_VERSION',      1243);
+define('DB_UPDATE_VERSION',      1244);
 define('NEW_UPDATE_ROUTINE_VERSION', 1170);
 
 /**
diff --git a/database.sql b/database.sql
index 054bcd9a1..506e252ec 100644
--- a/database.sql
+++ b/database.sql
@@ -1,6 +1,6 @@
 -- ------------------------------------------
 -- Friendica 3.6-dev (Asparagus)
--- DB_UPDATE_VERSION 1243
+-- DB_UPDATE_VERSION 1244
 -- ------------------------------------------
 
 
@@ -1006,6 +1006,7 @@ CREATE TABLE IF NOT EXISTS `user` (
 	`guid` varchar(64) NOT NULL DEFAULT '' COMMENT '',
 	`username` varchar(255) NOT NULL DEFAULT '' COMMENT '',
 	`password` varchar(255) NOT NULL DEFAULT '' COMMENT '',
+	`legacy_password` boolean NOT NULL DEFAULT 0 COMMENT 'Is the password hash double-hashed?',
 	`nickname` varchar(255) NOT NULL DEFAULT '' COMMENT '',
 	`email` varchar(255) NOT NULL DEFAULT '' COMMENT '',
 	`openid` varchar(255) NOT NULL DEFAULT '' COMMENT '',
diff --git a/mod/item.php b/mod/item.php
index 64b773c21..b3509dc89 100644
--- a/mod/item.php
+++ b/mod/item.php
@@ -951,7 +951,7 @@ function handle_tag(App $a, &$body, &$inform, &$str_tags, $profile_uid, $tag, $n
 		// Try to detect the contact in various ways
 		if (strpos($name, 'http://')) {
 			// At first we have to ensure that the contact exists
-			$id = Contact::getIdForURL($name);
+			Contact::getIdForURL($name);
 
 			// Now we should have something
 			$contact = Contact::getDetailsByURL($name);
@@ -968,25 +968,26 @@ function handle_tag(App $a, &$body, &$inform, &$str_tags, $profile_uid, $tag, $n
 				$contact = dba::selectFirst('contact', $fields, ['id' => $tagcid, 'uid' => $profile_uid]);
 			}
 
-			// select someone by nick and the name passed in the current network
+			// select someone by nick or attag in the current network
 			if (!DBM::is_result($contact) && ($network != "")) {
-				$condition = ['nick' => $name, 'network' => $network, 'uid' => $profile_uid];
+				$condition = ["(`nick` = ? OR `attag` = ?) AND `network` = ? AND `uid` = ?",
+						$name, $name, $network, $profile_uid];
 				$contact = dba::selectFirst('contact', $fields, $condition);
 			}
 
-			//select someone from this user's contacts by name in the current network
+			//select someone by name in the current network
 			if (!DBM::is_result($contact) && ($network != "")) {
 				$condition = ['name' => $name, 'network' => $network, 'uid' => $profile_uid];
 				$contact = dba::selectFirst('contact', $fields, $condition);
 			}
 
-			// select someone by nick in any network
+			// select someone by nick or attag in any network
 			if (!DBM::is_result($contact)) {
-				$condition = ['nick' => $name, 'uid' => $profile_uid];
+				$condition = ["(`nick` = ? OR `attag` = ?) AND `uid` = ?", $name, $name, $profile_uid];
 				$contact = dba::selectFirst('contact', $fields, $condition);
 			}
 
-			// select someone from this user's contacts by name
+			// select someone by name in any network
 			if (!DBM::is_result($contact)) {
 				$condition = ['name' => $name, 'uid' => $profile_uid];
 				$contact = dba::selectFirst('contact', $fields, $condition);
diff --git a/src/Database/DBStructure.php b/src/Database/DBStructure.php
index cb69b4952..b3eed0dd1 100644
--- a/src/Database/DBStructure.php
+++ b/src/Database/DBStructure.php
@@ -1708,6 +1708,7 @@ class DBStructure {
 						"guid" => ["type" => "varchar(64)", "not null" => "1", "default" => "", "comment" => ""],
 						"username" => ["type" => "varchar(255)", "not null" => "1", "default" => "", "comment" => ""],
 						"password" => ["type" => "varchar(255)", "not null" => "1", "default" => "", "comment" => ""],
+						"legacy_password" => ["type" => "boolean", "not null" => "1", "default" => "0", "comment" => "Is the password hash double-hashed?"],
 						"nickname" => ["type" => "varchar(255)", "not null" => "1", "default" => "", "comment" => ""],
 						"email" => ["type" => "varchar(255)", "not null" => "1", "default" => "", "comment" => ""],
 						"openid" => ["type" => "varchar(255)", "not null" => "1", "default" => "", "comment" => ""],
diff --git a/src/Model/User.php b/src/Model/User.php
index 382ec62cc..bbe424ecb 100644
--- a/src/Model/User.php
+++ b/src/Model/User.php
@@ -112,7 +112,7 @@ class User
 		if (is_object($user_info)) {
 			$user = (array) $user_info;
 		} elseif (is_int($user_info)) {
-			$user = dba::selectFirst('user', ['uid', 'password'],
+			$user = dba::selectFirst('user', ['uid', 'password', 'legacy_password'],
 				[
 					'uid' => $user_info,
 					'blocked' => 0,
@@ -122,7 +122,7 @@ class User
 				]
 			);
 		} elseif (is_string($user_info)) {
-			$user = dba::fetch_first('SELECT `uid`, `password`
+			$user = dba::fetch_first('SELECT `uid`, `password`, `legacy_password`
 				FROM `user`
 				WHERE (`email` = ? OR `username` = ? OR `nickname` = ?)
 				AND `blocked` = 0
@@ -138,17 +138,29 @@ class User
 			$user = $user_info;
 		}
 
-		if (!DBM::is_result($user) || !isset($user['uid']) || !isset($user['password'])) {
-			return false;
+		if (!DBM::is_result($user)
+			|| !isset($user['uid'])
+			|| !isset($user['password'])
+			|| !isset($user['legacy_password'])
+		) {
+			throw new Exception('Not enough information to authenticate');
 		}
 
-		$password_hashed = self::hashPassword($password);
+		if ($user['legacy_password']) {
+			if (password_verify(self::hashPasswordLegacy($password), $user['password'])) {
+				self::updatePassword($user['uid'], $password);
 
-		if ($password_hashed !== $user['password']) {
-			return false;
+				return $user['uid'];
+			}
+		} elseif (password_verify($password, $user['password'])) {
+			if (password_needs_rehash($user['password'], PASSWORD_DEFAULT)) {
+				self::updatePassword($user['uid'], $password);
+			}
+
+			return $user['uid'];
 		}
 
-		return $user['uid'];
+		return false;
 	}
 
 	/**
@@ -161,15 +173,26 @@ class User
 		return autoname(6) . mt_rand(100, 9999);
 	}
 
+	/**
+	 * Legacy hashing function, kept for password migration purposes
+	 *
+	 * @param string $password
+	 * @return string
+	 */
+	private static function hashPasswordLegacy($password)
+	{
+		return hash('whirlpool', $password);
+	}
+
 	/**
 	 * Global user password hashing function
 	 *
 	 * @param string $password
 	 * @return string
 	 */
-	private static function hashPassword($password)
+	public static function hashPassword($password)
 	{
-		return hash('whirlpool', $password);
+		return password_hash($password, PASSWORD_DEFAULT);
 	}
 
 	/**
@@ -197,7 +220,8 @@ class User
 		$fields = [
 			'password' => $pasword_hashed,
 			'pwdreset' => null,
-			'pwdreset_time' => null
+			'pwdreset_time' => null,
+			'legacy_password' => false
 		];
 		return dba::update('user', $fields, ['uid' => $uid]);
 	}
diff --git a/src/Util/ExAuth.php b/src/Util/ExAuth.php
index 847059d6d..8940c0205 100644
--- a/src/Util/ExAuth.php
+++ b/src/Util/ExAuth.php
@@ -226,7 +226,7 @@ class ExAuth
 		if ($a->get_hostname() == $aCommand[2]) {
 			$this->writeLog(LOG_INFO, 'internal auth for ' . $sUser . '@' . $aCommand[2]);
 
-			$aUser = dba::selectFirst('user', ['uid', 'password'], ['nickname' => $sUser]);
+			$aUser = dba::selectFirst('user', ['uid', 'password', 'legacy_password'], ['nickname' => $sUser]);
 			if (DBM::is_result($aUser)) {
 				$uid = $aUser['uid'];
 				$success = User::authenticate($aUser, $aCommand[3]);
diff --git a/update.php b/update.php
index 3cfc39e19..00b8d890e 100644
--- a/update.php
+++ b/update.php
@@ -5,8 +5,7 @@ use Friendica\Core\Config;
 use Friendica\Core\PConfig;
 use Friendica\Core\Worker;
 use Friendica\Database\DBM;
-use Friendica\Model\Photo;
-use Friendica\Object\Image;
+use Friendica\Model\User;
 
 /**
  *
@@ -146,3 +145,19 @@ function update_1203() {
 	$r = q("UPDATE `user` SET `account-type` = %d WHERE `page-flags` IN (%d, %d)",
 		dbesc(ACCOUNT_TYPE_COMMUNITY), dbesc(PAGE_COMMUNITY), dbesc(PAGE_PRVGROUP));
 }
+
+function update_1244() {
+	// Sets legacy_password for all legacy hashes
+	dba::update('user', ['legacy_password' => true], ['SUBSTR(password, 1, 4) != "$2y$"']);
+
+	// All legacy hashes are re-hashed using the new secure hashing function
+	$stmt = dba::select('user', ['uid', 'password'], ['legacy_password' => true]);
+	while($user = dba::fetch($stmt)) {
+		dba::update('user', ['password' => User::hashPassword($user['password'])], ['uid' => $user['uid']]);
+	}
+
+	// Logged in users are forcibly logged out
+	dba::delete('session', ['1 = 1']);
+
+	return UPDATE_SUCCESS;
+}