Answer Happy

= = Question 3 (30 points]: A generalization of the Caesar cipher, known as the affine Caesar cipher, has the following form: For each plaintext letter p, substitute the ciphertext letter C: С E([a, b],p) (ap + b) mod 26 A basic requirement of any encryption algorithm is that it be one-to-one. That is, if p = q, then Eſk, p) # Eſk, q). Otherwise, decryption is impossible, because more than one plaintext character maps into the same ciphertext character. The affine Caesar cipher is not one-to-one for all values of a for example, for a = 2 and b = 3, then E([a, b], 0) = E([a, b], 13) = 3. Assume that 0 s a, b < 25 then answer the following questions: = a) Are there any limitations on the value of b? Explain why or why not. b) Determine all values of a that are not allowed?