I don't think you can with a decent crypt. In practice most encrypted containers come with metadata and a header describing the type of encryption since the ass

I don't think you can with a decent crypt. In practice most encrypted containers come with metadata and a header describing the type of encryption since the assumption is that it can only be decrypted with a key anyway. If you forget encryption parameters, this can become difficult even if you have the key. In cryptanalysis it is normally assumed that the attacker knows the algorithm and encryption parameters aside the key.