(auth) add RFC 6238 (TOTP) authenticator for https://github.com/opnsense/core/issues/449

src/opnsense/mvc/app/library/OPNsense/Auth/LocalTOTP.php

+<?php
+/**
+ *    Copyright (C) 2015 Deciso B.V.
+ *
+ *    All rights reserved.
+ *
+ *    Redistribution and use in source and binary forms, with or without
+ *    modification, are permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ *
+ *    2. Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *
+ *    THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ *    INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ *    AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ *    AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+ *    OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *    POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+namespace OPNsense\Auth;
+
+require_once("Base32.php");
+
+/**
+ * RFC 6238 TOTP: Time-Based One-Time Password Authenticator
+ * @package OPNsense\Auth
+ */
+class LocalTOTP extends Local
+{
+    /**
+     * @var int time window in seconds (google auth uses 30, some hardware tokens use 60)
+     */
+    private $timeWindow = 30;
+
+    /**
+     * @var int key length (6,8)
+     */
+    private $otpLength = 6;
+
+    /**
+     * @var int number of seconds the clocks (local, remote) may differ
+     */
+    private $graceperiod = 10;
+
+    /**
+     * set connector properties
+     * @param array $config connection properties
+     */
+    public function setProperties($config)
+    {
+        parent::setProperties($config);
+        if (!empty($config['timeWindow'])) {
+            $this->timeWindow = $config['timeWindow'];
+        }
+        if (!empty($config['otpLength'])) {
+            $this->otpLength = $config['otpLength'];
+        }
+        if (!empty($config['graceperiod'])) {
+            $this->otpLength = $config['graceperiod'];
+        }
+    }
+
+    /**
+     * use graceperiod and timeWindow to calculate which moments in time we should check
+     * @return array timestamps
+     */
+    private function timesToCheck()
+    {
+        $result = array();
+        if ($this->graceperiod > $this->timeWindow) {
+            $step = $this->timeWindow;
+            $start = -1 * floor($this->graceperiod  / $this->timeWindow) * $this->timeWindow;
+        } else {
+            $step = $this->graceperiod;
+            $start = -1 * $this->graceperiod;
+        }
+        $now = time();
+        for ($count = $start ; $count <= $this->graceperiod ; $count += $step) {
+            $result[] = $now + $count;
+            if ($this->graceperiod == 0) {
+                // special case, we expect the clocks to match 100%, so step and target are both 0
+                break;
+            }
+        }
+        return $result;
+    }
+
+    /**
+     * @param int $moment timestemp
+     * @param string $secret secret to use
+     * @return calculated token code
+     */
+    private function calculateToken($moment, $secret)
+    {
+        // calculate binary 8 character time for provided window
+        $binary_time = pack("N", (int)($moment/$this->timeWindow));
+        $binary_time = str_pad($binary_time,8, chr(0), STR_PAD_LEFT);
+
+        // Generate the hash using the SHA1 algorithm
+        $hash = hash_hmac ('sha1', $binary_time, $secret, true);
+        $offset = ord($hash[19]) & 0xf;
+        $otp = (
+                ((ord($hash[$offset+0]) & 0x7f) << 24 ) |
+                ((ord($hash[$offset+1]) & 0xff) << 16 ) |
+                ((ord($hash[$offset+2]) & 0xff) << 8 ) |
+                (ord($hash[$offset+3]) & 0xff)
+            ) % pow(10, $this->otpLength);
+
+
+        $otp = str_pad($otp, $this->otpLength, "0", STR_PAD_LEFT);
+        return $otp;
+    }
+
+    /**
+     * authenticate TOTP RFC 6238
+     * @param string $secret secret seed to use
+     * @param string $code provided code
+     * @return bool is valid
+     */
+    private function authTOTP($secret, $code)
+    {
+        foreach ($this->timesToCheck() as $moment) {
+            if ($code == $this->calculateToken($moment, $secret)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * authenticate user against otp key stored in local database
+     * @param string $username username to authenticate
+     * @param string $password user password
+     * @return bool authentication status
+     */
+    public function authenticate($username, $password)
+    {
+        $userObject = $this->getUser($username);
+        if ($userObject != null && !empty($userObject->otp_seed)) {
+            if (strlen($password) > $this->otpLength) {
+                // split otp token code and userpassword
+                $code = substr($password, 0, $this->otpLength);
+                $userPassword =  substr($password, $this->otpLength);
+                $otp_seed = \Base32\Base32::decode($userObject->otp_seed);
+                if ($this->authTOTP($otp_seed, $code)) {
+                    // token valid, do local auth
+                    return parent::authenticate($userObject, $userPassword);
+                }
+            }
+        }
+        return false;
+    }
+}