{

protected $_codeLength = 6;

/**

public function createSecret($secretLength = 40)

{

$validChars = $this->_getBase32LookupTable();

unset($validChars[32]);

$secret = '';

for ($i = 0; $i < $secretLength; $i++) {

$secret .= $validChars[array_rand($validChars)];

}

return $secret;

}

/**

public function getCode($secret, $timeSlice = null)

{

if ($timeSlice === null) {

$timeSlice = floor(time() / 30);

}

$secretkey = $this->_base32Decode($secret);

// Pack time into binary string

$time = chr(0).chr(0).chr(0).chr(0).pack('N*', $timeSlice);

// Hash it with users secret key

$hm = hash_hmac('SHA1', $time, $secretkey, true);

// Use last nipple of result as index/offset

$offset = ord(substr($hm, -1)) & 0x0F;

// grab 4 bytes of the result

$hashpart = substr($hm, $offset, 4);

// Unpak binary value

$value = unpack('N', $hashpart);

$value = $value[1];

// Only 32 bits

$value = $value & 0x7FFFFFFF;

$modulo = pow(10, $this->_codeLength);

return str_pad($value % $modulo, $this->_codeLength, '0', STR_PAD_LEFT);

}

/**

public function getQRCodeGoogleUrl($name, $secret, $title = null) {

$urlencoded = urlencode('otpauth://totp/'.$name.'?secret='.$secret.'');

if(isset($title)) {

$urlencoded .= urlencode('&issuer='.urlencode($title));

}

return 'https://chart.googleapis.com/chart?chs=200x200&chld=M|0&cht=qr&chl='.$urlencoded.'';

}

/**

public function verifyCode($secret, $code, $discrepancy = 1, $currentTimeSlice = null)

{

if ($currentTimeSlice === null) {

$currentTimeSlice = floor(time() / 30);

}

for ($i = -$discrepancy; $i <= $discrepancy; $i++) {

$calculatedCode = $this->getCode($secret, $currentTimeSlice + $i);

if ($calculatedCode == $code ) {

return true;

}

}

return false;

}

/**

public function setCodeLength($length)

{

$this->_codeLength = $length;

return $this;

}

/**

protected function _base32Decode($secret)

{

if (empty($secret)) return '';

$base32chars = $this->_getBase32LookupTable();

$base32charsFlipped = array_flip($base32chars);

$paddingCharCount = substr_count($secret, $base32chars[32]);

$allowedValues = array(6, 4, 3, 1, 0);

if (!in_array($paddingCharCount, $allowedValues)) return false;

for ($i = 0; $i < 4; $i++){

if ($paddingCharCount == $allowedValues[$i] &&

substr($secret, -($allowedValues[$i])) != str_repeat($base32chars[32], $allowedValues[$i])) return false;

}

$secret = str_replace('=','', $secret);

$secret = str_split($secret);

$binaryString = "";

for ($i = 0; $i < count($secret); $i = $i+8) {

$x = "";

if (!in_array($secret[$i], $base32chars)) return false;

for ($j = 0; $j < 8; $j++) {

$x .= str_pad(base_convert(@$base32charsFlipped[@$secret[$i + $j]], 10, 2), 5, '0', STR_PAD_LEFT);

}

$eightBits = str_split($x, 8);

for ($z = 0; $z < count($eightBits); $z++) {

$binaryString .= ( ($y = chr(base_convert($eightBits[$z], 2, 10))) || ord($y) == 48 ) ? $y:"";

}

}

return $binaryString;

}

/**

protected function _getBase32LookupTable()

{

return array(

'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 7

'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 15

'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 23

'Y', 'Z', '2', '3', '4', '5', '6', '7', // 31

'=' // padding char

);

}