public static function compat_pbkdf2($algo, $password, $salt, $iterations, $length = 0, $rawOutput = false)
{
// check for hashing algorithm
if (!in_array(strtolower($algo), hash_algos())) {
trigger_error(sprintf('%s(): Unknown hashing algorithm: %s', __FUNCTION__, $algo), E_USER_WARNING);
return false;
}
// check for type of iterations and length
foreach ([4 => $iterations, 5 => $length] as $index => $value) {
if (!is_numeric($value)) {
trigger_error(sprintf('%s() expects parameter %d to be long, %s given', __FUNCTION__, $index, gettype($value)), E_USER_WARNING);
return null;
}
}
// check iterations
$iterations = (int) $iterations;
if ($iterations <= 0) {
trigger_error(sprintf('%s(): Iterations must be a positive integer: %d', __FUNCTION__, $iterations), E_USER_WARNING);
return false;
}
// check length
$length = (int) $length;
if ($length < 0) {
trigger_error(sprintf('%s(): Iterations must be greater than or equal to 0: %d', __FUNCTION__, $length), E_USER_WARNING);
return false;
}
// check salt
if (strlen($salt) > PHP_INT_MAX - 4) {
trigger_error(sprintf('%s(): Supplied salt is too long, max of INT_MAX - 4 bytes: %d supplied', __FUNCTION__, strlen($salt)), E_USER_WARNING);
return false;
}
// initialize
$derivedKey = '';
$loops = 1;
if ($length > 0) {
$loops = (int) ceil($length / strlen(hash($algo, '', $rawOutput)));
}
// hash for each blocks
for ($i = 1; $i <= $loops; $i++) {
$digest = hash_hmac($algo, $salt . pack('N', $i), $password, true);
$block = $digest;
for ($j = 1; $j < $iterations; $j++) {
$digest = hash_hmac($algo, $digest, $password, true);
$block ^= $digest;
}
$derivedKey .= $block;
}
if (!$rawOutput) {
$derivedKey = bin2hex($derivedKey);
}
if ($length > 0) {
return substr($derivedKey, 0, $length);
}
return $derivedKey;
}
