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Q1(1 point). (Modular exponentiation: Compute the result of a large power modulo a
number.) What is the prime factorization of 987654?
Q2(1 point). You agreed to use a Caesar cipher with a key for k=7 with a friend. While
sitting in a group, the friend hands you over a message that says "JOBJIHUAOHUOJVUN".
Decrypt the message?
Q3(1 point). You intercepted the following encrypted message that was encrypted
using a Caesar cipher: 'WKH'. The intended plaintext is 'RFC'. What key (k) was used for
the encryption?
Q4(1 point). Using the Permutation Cipher with the same key [3, 5, 1, 2, 4], what is the
plaintext for the ciphertext: CESUCEUSRQEFIRSUOCS?
(The unfilled matrix is filled with letter 'X', remove it to get the final answer).
Q5(1 point). Euler totient function of n (we use the Greek symbol phi to denote Euler
totient function) is the number of positive integers that are between 1 and n-1, inclusive,
and are relatively prime to n. What is the Euler totient function of 80?
Q6(1 point). Using the same notations as in the lecture, e.g., p and q are the two
primes and e and d are the public key and the private key, respectively, p =13, q = 29, e
=17. What is the value of phi(n) where phi(n) is the Euler Totient function of n and n is
the modulus of RSA cipher?
Q7(1 point). Using the same notations as in the lecture, e.g., p and q are the two
primes and e and d are the public key and the private key, respectively, p = 3, q = 31, e
= 11. Using the phi(n) that you found in question 6 and the Extended Euclidean
algorithm yields d = 55. What is the ciphertext C when encrypting M = 13?
Q8(1 point). Using the same notations as in the lecture, e.g., p and q are the two
primes and e and d are the public key and the private key, respectively, p = 5, q = 17
and e=7 The attacker nerforms a chosen-ciphertext attack (CCA) It has a known
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