Using two different ciphers and two 256-bit keys is overkill. One good symmetric cipher is the strongest part of any cryptosystem. The 256-bit key is well beyond being brute forces. The password, and system for making the key from the password, are the weak point. 2^256 is much larger than 10^16.
in reply to Re^4: Opening an Encrypted DB_File database
in thread Opening an Encrypted DB_File database