protected function _cipher_alias(&$cipher)
{
static $dictionary;
if (empty($dictionary)) {
$dictionary = array('mcrypt' => array('aes-128' => 'rijndael-128', 'aes-192' => 'rijndael-128', 'aes-256' => 'rijndael-128', 'des3-ede3' => 'tripledes', 'bf' => 'blowfish', 'cast5' => 'cast-128', 'rc4' => 'arcfour', 'rc4-40' => 'arcfour'), 'openssl' => array('rijndael-128' => 'aes-128', 'tripledes' => 'des-ede3', 'blowfish' => 'bf', 'cast-128' => 'cast5', 'arcfour' => 'rc4-40', 'rc4' => 'rc4-40'));
// Notes:
//
// - Rijndael-128 is, at the same time all three of AES-128,
// AES-192 and AES-256. The only difference between them is
// the key size. Rijndael-192, Rijndael-256 on the other hand
// also have different block sizes and are NOT AES-compatible.
//
// - Blowfish is said to be supporting key sizes between
// 4 and 56 bytes, but it appears that between MCrypt and
// OpenSSL, only those of 16 and more bytes are compatible.
// Also, don't know what MCrypt's 'blowfish-compat' is.
//
// - CAST-128/CAST5 produces a longer cipher when encrypted via
// OpenSSL, but (strangely enough) can be decrypted by either
// extension anyway.
// Also, it appears that OpenSSL uses 16 rounds regardless of
// the key size, while RFC2144 says that for key sizes lower
// than 11 bytes, only 12 rounds should be used. This makes
// it portable only with keys of between 11 and 16 bytes.
//
// - RC4 (ARCFour) has a strange implementation under OpenSSL.
// Its 'rc4-40' cipher method seems to work flawlessly, yet
// there's another one, 'rc4' that only works with a 16-byte key.
//
// - DES is compatible, but doesn't need an alias.
//
// Other seemingly matching ciphers between MCrypt, OpenSSL:
//
// - RC2 is NOT compatible and only an obscure forum post
// confirms that it is MCrypt's fault.
}
if (isset($dictionary[$this->_driver][$cipher])) {
$cipher = $dictionary[$this->_driver][$cipher];
}
}
