currently we have a mcrypt implentation on our systems to crypt some sensible data in our PHP application. Now we have a new requirement that we have to change the crypt module to openssl. Another thing which is important know is that we are using the cipher blowfish and the mode ecb. So I began to test what are differences and how I can decrypt mcrypt encrypted strings with openssl.
I used the standard PHP function:
Both methods are delivering different results. Second thing is that in the given cipher (blowfish) and mode (ecb) in both types different IV lengthes are required (openssl=0 and mcrypt=56).
Does anybody know how I can easily change the modules without having a big migration effort?
Thanks in advance!
UPDATE:
Here is the code, which I tested it:
<?php
function say($message){
if(!is_string($message)){
if(!isset($_SERVER["HTTP_USER_AGENT"])) echo "<pre>";
echo var_export($message, true) . ((!isset($_SERVER["HTTP_USER_AGENT"]) ? "\n" : "<br />"));
if(!isset($_SERVER["HTTP_USER_AGENT"])) echo "</pre>";
}else{
echo $message . ((!isset($_SERVER["HTTP_USER_AGENT"]) ? "\n" : "<br />"));
}
}
say("= Begin raw encryption");
$key = "anotherpass";
$str = "does it work";
say(" Params:");
say(" - String to encrypt '".$str."'");
say(" - Key: ".$key);
say("");
$params = array(
"openssl" => array(
"cipher" => "BF",
"mode" => "ECB",
),
"mcrypt" => array(
"cipher" => "blowfish",
"mode" => "ecb",
),
);
say("= Mcrypt");
$handler = mcrypt_module_open($params['mcrypt']['cipher'], '', $params['mcrypt']['mode'], '');
$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($handler), MCRYPT_RAND);
$keysize = mcrypt_enc_get_key_size($handler);
mcrypt_generic_init($handler,$key,"\0\0\0\0\0\0\0\0");
say(" Params:");
say(" - InitVector ".bin2hex($iv)." (bin2hex)");
say(" - Max keysize ".$keysize);
say(" - Cipher ".$params['mcrypt']['cipher']);
say(" - Mode ".$params['mcrypt']['mode']);
say("");
say(" Encryption:");
$m_encrypted = mcrypt_generic($handler, $str);
$m_decrypted = mdecrypt_generic($handler, $m_encrypted);
say(" - Encrypted ".bin2hex($m_encrypted)." (bin2hex)");
say(" - Descrypted ".$m_decrypted);
say("");
say("= Openssl");
say(" Params:");
say(" - InitVector not needed");
say(" - Max keysize ".openssl_cipher_iv_length($params['openssl']['cipher']."-".$params['openssl']['mode']));
say(" - Cipher ".$params['openssl']['cipher']);
say(" - Mode ".$params['openssl']['mode']);
say("");
say(" Encryption:");
$o_encrypted = openssl_encrypt($str,$params['openssl']['cipher']."-".$params['openssl']['mode'],$key,true);
$o_decrypted = openssl_decrypt($o_encrypted,$params['openssl']['cipher']."-".$params['openssl']['mode'],$key,true);
say(" - Encrypted ".bin2hex($o_encrypted)." (bin2hex)");
say(" - Descrypted ".$o_decrypted);
And this is my result:
= Begin raw encryption
Params:
- String to encrypt 'does it work'
- Key: anotherpass
= Mcrypt
Params:
- InitVector 06a184909d7bf863 (bin2hex)
- Max keysize 56
- Cipher blowfish
- Mode ecb
Encryption:
- Encrypted 0e93dce9a6a88e343fe5f90d1307684c (bin2hex)
- Descrypted does it work
= Openssl
Params:
- InitVector not needed
- Max keysize 0
- Cipher BF
- Mode ECB
Encryption:
- Encrypted 213460aade8f9c14d8d51947b8231439 (bin2hex)
- Descrypted does it work
Maybe any ideas now?
Thanks!
Blowfish is the block cipher. It requires the data to be padded before encryption.
OpenSSL uses PKCS#7 and mcrypt uses PKCS#5. Different padding algorythms for data.
Minimal PKCS#5 padding length is 0, for PKCS#7 it's 1 (wikipedia). Take a look at this example (i've manually padded input data for mcrypt_encrypt()
in PKCS#7 style):
<?php
$key = "anotherpassword1";
$str = "does it work 12";
$enc = mcrypt_encrypt(MCRYPT_BLOWFISH, $key, $str."\1", MCRYPT_MODE_ECB);
$dec = mcrypt_decrypt(MCRYPT_BLOWFISH, $key, $enc, MCRYPT_MODE_ECB);
echo(bin2hex($enc).PHP_EOL);
var_dump($dec);
$enc = openssl_encrypt($str, 'bf-ecb', $key, true);
$dec = openssl_decrypt($enc, 'bf-ecb', $key, true);
echo(bin2hex($enc).PHP_EOL);
var_dump($dec);
?>
It's impossible to openssl_decrypt() data encrypted with mcrypt_encrypt(), unless manual data padding was made with PKCS#7 before mcrypt_encrypt()
was called.
There is only one way in your case - recrypt the data.
PS: There is an error in your source - ECB mode does not uses IV at all (wikipedia)