3. * Block ciphers with Feistel (or NLFSR) structure. We have learned that DES is an NLFSR, but the nonlinear feedback function is given by 32 4-bit permutations. In 2013, NSA presented two new cipher families, called Simon and Speck. In the Simon design, there are two registers where each holds n bits. Assume that an initial state of the NLFSR is given by P(ao, a1), a message with 2n bits, a 2n-bit key is denoted as A has 2n bits, and the feedback function is given by where L is the cyclic shift operator. Li means shift by i times, example, we assume that n -4, the cipher text is given by 2.8. Now for a toy where we assume for every other round, the key is repeated 3. * Block ciphers with Feistel (or NLFSR) structure. We have learned that DES is an NLFSR, but the nonlinear feedback function is given by 32 4-bit permutations. In 2013, NSA presented two new cipher families, called Simon and Speck. In the Simon design, there are two registers where each holds n bits. Assume that an initial state of the NLFSR is given by P(ao, a1), a message with 2n bits, a 2n-bit key is denoted as A has 2n bits, and the feedback function is given by where L is the cyclic shift operator. Li means shift by i times, example, we assume that n -4, the cipher text is given by 2.8. Now for a toy where we assume for every other round, the key is repeated