Optimizing mcrypt encryption class further

Question

The following is a very simple implementation of an Encryption class using mcrypt whereby the functions encrypt and decrypt are called statically by a PHP script on GET and on POST respectively:

class Encryption
{
 const CIPHER...
 static function encrypt($plaintext)
 {
 $td = mcrypt_module_open(self::CIPHER, "", self::MODE, ""); # <= move this outside?
 mcrypt_generic_init($td, self::KEY, 0);
 $ciphertext = mcrypt_generic($td, $plaintext);
 mcrypt_generic_deinit($td);
 mcrypt_module_close($td);
 return base64_encode($ciphertext);
 }
 static function decrypt($ciphertext)
 {
 $td = mcrypt_module_open(self::CIPHER, "", self::MODE, ""); # <= repeated
 mcrypt_generic_init($td, self::KEY, 0);
 $plaintext = mdecrypt_generic($td, base64_decode($ciphertext));
 mcrypt_generic_deinit($td);
 mcrypt_module_close($td);
 return $plaintext;
 }
}

Ignoring other aspects of this stripped down code, what I want to achieve is to reduce code duplication by perhaps moving $td = mcrypt_module_open(self::CIPHER, "", self::MODE, ""); outside. Can this be done without combining the two methods or is what I have already at the optimum?

Answer 1

You can actually refactor most of the code into a separate function:

static function encryptdecrypt($text)
{
 $td = mcrypt_module_open(self::CIPHER, "", self::MODE, "");
 mcrypt_generic_init($td, self::KEY, 0);
 $text = mcrypt_generic($td, $text);
 mcrypt_generic_deinit($td);
 mcrypt_module_close($td);
 return $text;
}
static function encrypt($plaintext)
{
 return base64_encode(encryptdecrypt($plaintext));
}
static function decrypt($ciphertext)
{
 return encryptdecrypt(base64_decode($ciphertext));
}

• Question Overflow: Nice try. But for decrypt, it uses the function mdecrypt_generic instead of mcrypt_generic. But I get your idea. Thanks!
• Guffa: @QuestionOverflow: Oh, I didn't spot that difference. You could send a flag into the function for which function to call.