Question - This is your chance to break a cryptosystem.
As we know by now, cryptography is a tricky business. The following problem illustrates how easy it is to turn a strong scheme into a weak one with minor modifications.
We saw in this chapter that key whitening is a good method for strengthening block ciphers against brute-force attacks.
We now look at the given variant of key whitening against DES, which we'll call DESA: DESAk,k1 (x) =DESk(x)?k1.
Even though the method looks same as to key whitening, it hardly adds to the security.
Your task is to show that breaking the scheme is roughly as difficult as a brute-force attack against single DES. Suppose you have a few pairs of plaintext - Ciphertext.
Explain the output of each stage as a list. Is there anybody who knows how to do this?