| protected cryptUnpadText ( string $text, string $mode, integer $blockSize, integer $paddingType ) : string | ||
| $text | string | Message to be unpadded |
| $mode | string | Encryption mode; unpadding is applied only in CBC or ECB mode |
| $blockSize | integer | Cipher block size |
| $paddingType | integer | Padding scheme |
| return | string | |
protected function cryptUnpadText($text, $mode, $blockSize, $paddingType)
{
$paddingSize = 0;
$length = strlen($text);
if ($length > 0 && $length % $blockSize == 0 && ($mode == MCRYPT_MODE_CBC || $mode == MCRYPT_MODE_ECB)) {
switch ($paddingType) {
case self::PADDING_ANSI_X_923:
$last = substr($text, $length - 1, 1);
$ord = (int) ord($last);
if ($ord <= $blockSize) {
$paddingSize = $ord;
$padding = str_repeat(chr(0), $paddingSize - 1) . $last;
if (substr($text, $length - $paddingSize) != $padding) {
$paddingSize = 0;
}
}
break;
case self::PADDING_PKCS7:
$last = substr($text, $length - 1, 1);
$ord = (int) ord($last);
if ($ord <= $blockSize) {
$paddingSize = $ord;
$padding = str_repeat(chr($paddingSize), $paddingSize);
if (substr($text, $length - $paddingSize) != $padding) {
$paddingSize = 0;
}
}
break;
case self::PADDING_ISO_10126:
$last = substr($text, $length - 1, 1);
$paddingSize = (int) ord($last);
break;
case self::PADDING_ISO_IEC_7816_4:
$i = $length - 1;
while ($i > 0 && $text[$i] == 0x0 && $paddingSize < $blockSize) {
$paddingSize++;
$i--;
}
if ($text[$i] == 0x80) {
$paddingSize++;
} else {
$paddingSize = 0;
}
break;
case self::PADDING_ZERO:
$i = $length - 1;
while ($i >= 0 && $text[$i] == 0x0 && $paddingSize <= $blockSize) {
$paddingSize++;
$i--;
}
break;
case self::PADDING_SPACE:
$i = $length - 1;
while ($i >= 0 && $text[$i] == 0x20 && $paddingSize <= $blockSize) {
$paddingSize++;
$i--;
}
break;
default:
break;
}
if ($paddingSize && $paddingSize <= $blockSize) {
if ($paddingSize < $length) {
return substr($text, 0, $length - $paddingSize);
}
return "";
}
}
return $text;
}