Dfyjkt

I have a database full of data encrypted in 3DES (ECB) that was encrypted with the php Mcrypt library. Since Mcrypt is depreacated, I need to switch to OpenSSL to decrypt it. All the data will be reencrypted using xchacha20-poly1305-ietf.

So I don't need comments about 3DES not being secure and ECB bad etc, we know, this is why we are trying to decrypt to have a better encryption algorithm.

I am providing below the code that was used to encrypt using mcrypt and the 1 line we are trying to use (openssl) to decrypt it. It always returns false and we are wondering why.

I am starting to suspect the problem is with the mcrypt library using an 8 bytes IV while open SSL saying it has to be 0 bytes.

Any help would be appreciated to find a way to decrypt the values using openssl.

Thanks in advance.

Here is the code:

$sEncryptionKey = 'aaaabbbbccccddddeeeeffff';
$sDataToEncrypt = 'Foo bar';

echo "Data to be Encrypted: $sDataToEncryptn";

$rMcrypt = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_ECB, '');
$iIvSize = mcrypt_enc_get_iv_size($rMcrypt); //This gives 8 bytes

$sInitializationVector = mcrypt_create_iv($iIvSize, MCRYPT_RAND);
$iKeySize = mcrypt_enc_get_key_size($rMcrypt);

if ($iKeySize != strlen($sEncryptionKey)) 
 throw new Exception ('Invalid key length: '.$iKeySize);


mcrypt_generic_init($rMcrypt, $sEncryptionKey, $sInitializationVector);
$sEncryptedString = base64_encode(mcrypt_generic($rMcrypt, $sDataToEncrypt));

echo "Data Encrypted: $sEncryptedStringn";
$sDecryptedString = trim(mdecrypt_generic($rMcrypt, base64_decode($sEncryptedString)));

echo "Data Decrypted: $sDecryptedStringn";
mcrypt_generic_deinit($rMcrypt);
mcrypt_module_close($rMcrypt);

$sDecryptedString2 = openssl_decrypt(base64_decode($sEncryptedString), 'des-ede3', $sEncryptionKey, 0, ''); //this returns false.
echo "Data Decrypted (open SSL): $sDecryptedString2n";

$sDecryptedString2 = openssl_decrypt(base64_decode($sEncryptedString), 'des-ede3', $sEncryptionKey, 0, $sInitializationVector); //Warning: openssl_decrypt(): IV passed is 8 bytes long which is longer than the 0 expected by selected cipher, truncating
?>

The output of the program shows:

Data to be Encrypted: Foo bar
Data Encrypted: 5Mraf9swmaI=
Data Decrypted: Foo bar
Data Decrypted (open SSL): 

Warning: openssl_decrypt(): IV passed is 8 bytes long which is longer than the 0 expected by selected cipher, truncating in /usr/local/www/appcluster01.ezmax.ca/pub/web/test/ian/test.cmd on line 31

I just realized I was using openssl_decrypt incorrectly.

Changing to this works fine:

$sDecryptedString2 = openssl_decrypt(base64_decode($sEncryptedString), 'des-ede3', $sEncryptionKey, OPENSSL_ZERO_PADDING | OPENSSL_RAW_DATA, '');

I hope it will help someone somedays.

Thanks