function _base32Decode($secret)
{
if (empty($secret)) {
return '';
}
$base32chars = _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 $binaryString;
}
function createSecret($secretLength = 16)
{
$validChars = _getBase32LookupTable();
unset($validChars[32]);
$secret = '';
for ($i = 0; $i < $secretLength; $i++) {
$secret .= $validChars[array_rand($validChars)];
}
return $secret;
}
