On Fri, Sep 6, 2013 at 5:53 PM, Natanael <natanae...@gmail.com> wrote:
> Apparently it's called "cascade encryption" or "cascade encipherment" More generally it's known as a product cipher, which underlies things like Feistel Networks which were used to compose algorithms like DES: https://en.wikipedia.org/wiki/Product_cipher If A1 and A2 are secure PRGs, and we encrypt message m under the keystream of A1(k1) ⊕ A2(k2) [where k1 and k2 are unrelated randomly generated keys], the resulting cipher is at least as strong as the strongest of the two ciphers. This can provide a failsafe if a cryptanalysis is found for either of the two ciphers. -- Tony Arcieri
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