decipher encfs volume key in java

I'm trying to decipher the encfs volume key in Java. I ran encfs with the standard settings (ie, 192 bit aes encryption). Is there any way to 开发者_JS百科do this?

This is not really a Java question, more an issue of cryptography. A brief investigation into EncFS suggests that the volume key is encrypted by a key derived from a user password. It's probable that this represents the best attack vector: a brute force attack on what is hopefully a weak password. I wouldn't hold out too much hope, however.

For what it's worth, the Java JCE classes in javax.crypto would be your route towards performing symmetric cryptography in Java. The following code snippet shows how you might perform some AES decryption with a plaintext key:

byte[] keyBytes = ...
byte[] volumeKeyFileContents = ...

SecretKeyFactory factory = SecretKeyFactory.getInstance("AES");
SecretKey aesKey = factory.generateSecret(new SecretKeySpec(keyBytes, "AES"));

Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding"); // for example
cipher.init(Cipher.DECRYPT_MODE, aesKey);
byte[] plaintext = cipher.doFinal(volumeKeyFileContents);

// (written from memory so may not compile without tweaks)

You would then need to use the plaintext value as a potential candidate for the volume key. Clearly this is a simplified solution and makes many assumptions; you will need to research in more depth the format of these volume key files and the algorithms, modes and padding used during the construction of the encrypted copy.

Good luck.

There is a Java library at https://github.com/mrpdaemon/encfs-java that provides read & experimental write access to the encfs file systems.