Let F be a single round of a Feistel cipher operating on 64-bit blocks. That means...

 

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Let F be a single round of a Feistel cipher operating on 64-bit blocks. That means an input a = (aL, aR) where aL and aR are 32 bits long each, and F(aL, aR) (aR, aL xor f(aR, k)). f is the Feistel cipher's "secret" function. = Suppose that (aL, aR) and (bL, bR) are a pair of plaintexts such that aR xor bR = q for some number q. Consider what happens when we run two rounds of the Feistel Cipher on the input a, and two rounds of the Feistel Cipher on b: = (CL, CR) F(F(aL, aR)), (dL, dR) = = F(F(bL, bR)) Show that if CL = dL, then CR xor dr = q. Let F be a single round of a Feistel cipher operating on 64-bit blocks. That means an input a = (aL, aR) where aL and aR are 32 bits long each, and F(aL, aR) (aR, aL xor f(aR, k)). f is the Feistel cipher's "secret" function. = Suppose that (aL, aR) and (bL, bR) are a pair of plaintexts such that aR xor bR = q for some number q. Consider what happens when we run two rounds of the Feistel Cipher on the input a, and two rounds of the Feistel Cipher on b: = (CL, CR) F(F(aL, aR)), (dL, dR) = = F(F(bL, bR)) Show that if CL = dL, then CR xor dr = q.