Q1(1 point). What is the prime factorization for 31293570?
Q2(1 point). You agreed to use a Caesar cipher with a key of k-4 with a friend.
While sitting in a group, the friend hands you over a message that says
"AIHRIWHEC". Decrypt the message?
Q3(1 point). Suppose you actually forgot the key. How many decryption
computations of the cipher text "IXEVZU" do you need to perform to reach to
the plaintext?
Q4(1 point). Using the Permutation Cipher with the same key [35124], what
is the ciphertext for the plaintext GOODTHINGSTAKETIME? (Leave the
unfilled matrix as blank).
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
72?
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 = 7, q
= 13, e = 7. 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 = 7, q
= 13, e = 7. Using the phi(n) that you found in the question 6 and the Extended
Euclidean algorithm yields d = 31. What is the ciphertext C when encrypting M
= 19?
Q8(1 point). Using the same notations as in the lecture, e.g., p and q are the two
