Add google_authenticator PHP class

This class is licensed under Apache version 2.0

resources/classes/google_authenticator.php

@@ -0,0 +1,85 @@
+<?php
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// @package     GoogleAuthenticator
+// @link        https://github.com/chregu/GoogleAuthenticator.php
+// @author      Christian Stocker
+// @license     http://www.apache.org/licenses/LICENSE-2.0  Apache 2.0
+
+class google_authenticator {
+	static $PASS_CODE_LENGTH = 6;
+	static $PIN_MODULO;
+	static $SECRET_LENGTH = 10;
+
+	public function __construct() {
+		self::$PIN_MODULO = pow(10, self::$PASS_CODE_LENGTH);
+	}
+
+	public function checkCode($secret,$code) {
+		$time = floor(time() / 30);
+		for ( $i = -1; $i <= 1; $i++) {
+			if ($this->getCode($secret,$time + $i) == $code) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	public function getCode($secret,$time = null) {
+
+		if (!$time) {
+			$time = floor(time() / 30);
+		}
+
+		$base32 = new FixedBitNotation(5, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567', TRUE, TRUE);
+		$secret = $base32->decode($secret);
+
+		$time = pack("N", $time);
+		$time = str_pad($time,8, chr(0), STR_PAD_LEFT);
+
+		$hash = hash_hmac('sha1',$time,$secret,true);
+		$offset = ord(substr($hash,-1));
+		$offset = $offset & 0xF;
+
+		$truncatedHash = self::hashToInt($hash, $offset) & 0x7FFFFFFF;
+		$pinValue = str_pad($truncatedHash % self::$PIN_MODULO,6,"0",STR_PAD_LEFT);;
+		return $pinValue;
+	}
+
+	protected function hashToInt($bytes, $start) {
+		$input = substr($bytes, $start, strlen($bytes) - $start);
+		$val2 = unpack("N",substr($input,0,4));
+		return $val2[1];
+	}
+
+	public function getUrl($user, $hostname, $secret) {
+		$url = sprintf("otpauth://totp/%s@%s?secret=%s", $user, $hostname, $secret);
+		$encoder = "https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=";
+		$encoderURL = sprintf( "%sotpauth://totp/%s@%s&secret=%s",$encoder, $user, $hostname, $secret);
+		return $encoderURL;
+	}
+
+	public function generateSecret() {
+		$secret = "";
+		for($i = 1;  $i<= self::$SECRET_LENGTH;$i++) {
+			$c = rand(0,255);
+			$secret .= pack("c",$c);
+		}
+
+		$base32 = new FixedBitNotation(5, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567', TRUE, TRUE);
+		return  $base32->encode($secret);
+	}
+
+}
+
+?>