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libraries/f0f/encrypt/totp.php

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+<?php
+/**
+ * @package    FrameworkOnFramework
+ * @subpackage encrypt
+ * @copyright   Copyright (C) 2010-2016 Nicholas K. Dionysopoulos / Akeeba Ltd. All rights reserved.
+ * @license    GNU General Public License version 2 or later; see LICENSE.txt
+ */
+defined('F0F_INCLUDED') or die;
+
+/**
+ * This class provides an RFC6238-compliant Time-based One Time Passwords,
+ * compatible with Google Authenticator (with PassCodeLength = 6 and TimePeriod = 30).
+ *
+ * @package  FrameworkOnFramework
+ * @since    1.0
+ */
+class F0FEncryptTotp
+{
+	private $_passCodeLength = 6;
+
+	private $_pinModulo;
+
+	private $_secretLength = 10;
+
+	private $_timeStep = 30;
+
+	private $_base32 = null;
+
+	/**
+	 * Initialises an RFC6238-compatible TOTP generator. Please note that this
+	 * class does not implement the constraint in the last paragraph of §5.2
+	 * of RFC6238. It's up to you to ensure that the same user/device does not
+	 * retry validation within the same Time Step.
+	 *
+	 * @param   int     $timeStep        The Time Step (in seconds). Use 30 to be compatible with Google Authenticator.
+	 * @param   int     $passCodeLength  The generated passcode length. Default: 6 digits.
+	 * @param   int     $secretLength    The length of the secret key. Default: 10 bytes (80 bits).
+	 * @param   Object  $base32          The base32 en/decrypter
+	 */
+	public function __construct($timeStep = 30, $passCodeLength = 6, $secretLength = 10, $base32=null)
+	{
+		$this->_timeStep       = $timeStep;
+		$this->_passCodeLength = $passCodeLength;
+		$this->_secretLength   = $secretLength;
+		$this->_pinModulo      = pow(10, $this->_passCodeLength);
+
+		if (is_null($base32))
+		{
+			$this->_base32 = new F0FEncryptBase32;
+		}
+		else
+		{
+			$this->_base32 = $base32;
+		}
+	}
+
+	/**
+	 * Get the time period based on the $time timestamp and the Time Step
+	 * defined. If $time is skipped or set to null the current timestamp will
+	 * be used.
+	 *
+	 * @param   int|null  $time  Timestamp
+	 *
+	 * @return  int  The time period since the UNIX Epoch
+	 */
+	public function getPeriod($time = null)
+	{
+		if (is_null($time))
+		{
+			$time = time();
+		}
+
+		$period = floor($time / $this->_timeStep);
+
+		return $period;
+	}
+
+	/**
+	 * Check is the given passcode $code is a valid TOTP generated using secret
+	 * key $secret
+	 *
+	 * @param   string  $secret  The Base32-encoded secret key
+	 * @param   string  $code    The passcode to check
+	 *
+	 * @return boolean True if the code is valid
+	 */
+	public function checkCode($secret, $code)
+	{
+		$time = $this->getPeriod();
+
+		for ($i = -1; $i <= 1; $i++)
+		{
+			if ($this->getCode($secret, ($time + $i) * $this->_timeStep) == $code)
+			{
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Gets the TOTP passcode for a given secret key $secret and a given UNIX
+	 * timestamp $time
+	 *
+	 * @param   string  $secret  The Base32-encoded secret key
+	 * @param   int     $time    UNIX timestamp
+	 *
+	 * @return string
+	 */
+	public function getCode($secret, $time = null)
+	{
+		$period = $this->getPeriod($time);
+		$secret = $this->_base32->decode($secret);
+
+		$time = pack("N", $period);
+		$time = str_pad($time, 8, chr(0), STR_PAD_LEFT);
+
+		$hash = hash_hmac('sha1', $time, $secret, true);
+		$offset = ord(substr($hash, -1));
+		$offset = $offset & 0xF;
+
+		$truncatedHash = $this->hashToInt($hash, $offset) & 0x7FFFFFFF;
+		$pinValue = str_pad($truncatedHash % $this->_pinModulo, $this->_passCodeLength, "0", STR_PAD_LEFT);
+
+		return $pinValue;
+	}
+
+	/**
+	 * Extracts a part of a hash as an integer
+	 *
+	 * @param   string  $bytes  The hash
+	 * @param   string  $start  The char to start from (0 = first char)
+	 *
+	 * @return  string
+	 */
+	protected function hashToInt($bytes, $start)
+	{
+		$input = substr($bytes, $start, strlen($bytes) - $start);
+		$val2 = unpack("N", substr($input, 0, 4));
+
+		return $val2[1];
+	}
+
+	/**
+	 * Returns a QR code URL for easy setup of TOTP apps like Google Authenticator
+	 *
+	 * @param   string  $user      User
+	 * @param   string  $hostname  Hostname
+	 * @param   string  $secret    Secret string
+	 *
+	 * @return  string
+	 */
+	public function getUrl($user, $hostname, $secret)
+	{
+		$url = sprintf("otpauth://totp/%s@%s?secret=%s", $user, $hostname, $secret);
+		$encoder = "https://chart.googleapis.com/chart?chs=200x200&chld=Q|2&cht=qr&chl=";
+		$encoderURL = $encoder . urlencode($url);
+
+		return $encoderURL;
+	}
+
+	/**
+	 * Generates a (semi-)random Secret Key for TOTP generation
+	 *
+	 * @return  string
+	 */
+	public function generateSecret()
+	{
+		$secret = "";
+
+		for ($i = 1; $i <= $this->_secretLength; $i++)
+		{
+			$c = rand(0, 255);
+			$secret .= pack("c", $c);
+		}
+		$base32 = new F0FEncryptBase32;
+
+		return $this->_base32->encode($secret);
+	}
+}