Suppose E1 and E2 are two encryption methods. Let t1 and t2 be two keys belonging to Z26. Define E1.

Suppose E1 and E2 are two encryption methods. Let t1 and t2 be two keys belonging to Z26. Define E1 be an encryption, which involves multiplying the plaintext, m also belonging to Z26 by t1. Similarly, define E2 as an encryption which involves adding the input with t2, modulo 26. Answer the following questions regarding the above ciphers and their composition: i. What is the requirement of t1 for the cipher E1 to be an encryption algorithm? (Note encryption algorithms are reversible). ii. What is the composition of the ciphers, denoted by E1 ? E2 popularly known as in classical cryptography? Note given a plaintext, m from Z26, the ciphertext c is given by c = t1m + t2(mod 26). iii. What is the brute force complexity to break the cipher (i,e what is the total number of values of t1, t2)? iv. Develop a meet in the middle attack against the cipher, and show that there are exactly 38 encryptions required.