protected function encryptString($str)
{
if ($this->bits % 8 != 0) {
throw new \RuntimeException("Number of bits should be divisable by 8 when encrypting a string!");
}
$step = $this->bits / 8;
$size = strlen($str);
if (!$size) {
return '';
}
$result = '';
$compensation = 0;
for ($offset = 0; $offset < $size; $offset += $step) {
$substr = substr($str, $offset, $step);
if (strlen($substr) != $step) {
$compensation = $step - strlen($substr);
$substr .= str_repeat("", $compensation);
}
$unpacked = unpack('C*', $substr);
$val = 0;
$first = true;
foreach ($unpacked as $num) {
if ($first) {
$first = false;
} else {
$val <<= 8;
}
$val += $num & 0xff;
}
$encrypted = $this->encrypt($val);
for ($i = 0; $i < $step; ++$i) {
$partition = $encrypted & 0xff;
$packed = pack('C', $partition);
$result .= $packed;
$encrypted = CommonUtils::unsignedRightShift($encrypted, 8);
}
}
return pack('C', $compensation) . $result;
}