Question

As in the previous question, consider a Feistel cipher that has only 5 rounds.

Suppose further that the round function F(X,K_i ), which takes in input a block X and a round key K_i , is defined as F(X, K_i ) = X ⊕ K_i and that

• the cipher works on blocks of 4 bits,
• the round key K₁ is 1010 and all other round keys are defined by the equation K_i+1 = K_i⊕ 1011,
• the input is LE₀|| RE₀ = 11000011

Which is the output of the decryption round 1?

Answer 1

Round 1 key "K₁" = 1010

Input text = 11000011

LE₀ = 1100

RE₀ = 0011

You have not specified that wether this input is already encrypted or not and you asked for output of decryption round 1, So I am assuming that the input is already encrypted. Now,