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★right first attempt
✓right
✗wrong

NTC PS03EMTH55 (01-11-2023)
Question 1. Which of the following is a primitive root modulo 11?
i)
3
ii)
5
iii)
7
iv)
9

Question 2. Let a,m ∈ ℕ. Consider the following statements.
(i)
∃ ⁡b ∈ ℕ such that ab ≡ 1(modm).
(ii)
gcd ⁡ (a,m) = 1.
Which of the following is true?
i)
(i) ⇒ (ii) but (ii) ⇏ (i)
ii)
(i) ⇒ (ii) and (ii) ⇒ (i)
iii)
(ii) ⇒ (i) but (i) ⇏ (ii)
iv)
(i) ⇏ (ii) and (ii) ⇏ (i)

Question 3. Let p be a prime satisfying p ≡ 3(mod4) and a be an integer. Then     a solution of the congruence x2 ≡ a(modp).
i)
a(p+1)∕4(modp) is
ii)
a(p+1)∕2(modp) is
iii)
a(p+3)∕4(modp) is
iv)
there need not be

Question 4. An attack in which an eavesdropper has access to an oracle that decrypts arbitrary ciphertexts is known as a     attack.
i)
chosen ciphertext
ii)
man-in-the-middle
iii)
known plaintext
iv)
chosen plaintext

Question 5. A number whose prime factors are all less than or equal to k is called a     number.
i)
composite
ii)
Miller-Rabin
iii)
k-smooth
iv)
Carmichael

Question 6. ϕ(100) =     .
i)
4
ii)
10
iii)
40
iv)
99

Question 7. The discriminant of an elliptic curve E : Y 2 = X3 + AX + B is given by     .
i)
27A2 + 4B3
ii)
27A3 + 4B2
iii)
4A2 + 27B3
iv)
4A3 + 27B2

Question 8. Let E : Y 2 = X3 + X + 2 be an elliptic curve over 𝔽5. Then #E(𝔽5) =     .
i)
3
ii)
4
iii)
25
iv)
none of these