Hot answers tagged multiple-encryption
Cascading cipher gives a sense of security; and one that is technically justified with respect to the possibility that a weakness in one of the cipher would allow recovering the encrypted data. That's Bruce Schneier's argument, and it made sense in an era where DES, the then leading cipher, was a closed design, clearly deliberately weakened by a small key, ...
Your first option: Encrypted(Input) = AES256(key2, Serpent(key1, Input)) suffers from a textbook meet-in-the-middle attack. It only gives you one additional bit of security over AES alone / Serpent alone. Not a good choice if you're aiming for extra paranoia.
Step 1: good job, this is the right way. You can also use bcrypt or scrypt for extra resistance. Make sure you have chosen sufficiently strong parameters, that is, 64-bit salt and 10000 rounds absolute minimum. Step 2: no! once you have a strong derived master key, you don't need to apply PBKDF2 on any keys derived from this master key. You are just wasting ...
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