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<?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.
include_once("FixedByteNotation.php");
class GoogleAuthenticator {
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);
}
}
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