10.3.2023
Question 1: We know that gcd(5,9)=1, i.e., 5 and 9 are “relatively prime”. So 5 has a MI in $Z_{9}$. Which of the following integers in the MI (Multiplicative Inverse) of 5 in $Z_{9}$?
(3 points)
A. 2
B. 3
C. 4
D. 6
Answer
A. 2Question 2: For a given prime number $p$, what is the size $\phi(p)$? That is, $\vert \phi(p) \vert =$ ?
(3 points)
A. $p-2$
B. $p-1$
C. $p$
D. $p+1$
Answer
B. $p-1$Question 3: In RSA encryption, we encrypt the message using a public key $e$ that is relatively prime with?
(3 points)
A. $n$, the modulus (product of two primes)
B. any integer in $Z_{n}$
C. $\phi(n)$, Euler’s totient
D. None of the above