Using 'RSA' algorithm, if π = 13,π = 5 and π = 7. the value of π andβ¦
2022
UsingΒ 'RSA'Β algorithm, ifΒ π = 13,π = 5Β andΒ π = 7. the value ofΒ πΒ and cipher value ofΒ β²6β²Β withΒ (π,π)Β key are
- A.
7,4
- B.
7,1
- C.
7,46
- D.
55,1
Attempted by 63 students.
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Correct answer: C
Step 1: Compute n and phi(n).
n = p * q = 13 * 5 = 65. phi(n) = (p-1)*(q-1) = 12 * 4 = 48.
Step 2: Find d such that d * e β‘ 1 (mod 48).
We need the modular inverse of e = 7 modulo 48. Since 7 * 7 = 49 β‘ 1 (mod 48), we have d = 7.
Step 3: Encrypt m = 6 using the public key (e, n) = (7, 65).
Compute powers of 6 modulo 65 to get 6^7 mod 65:
6^2 = 36
6^3 = 6^2 * 6 β‘ 36 * 6 = 216 β‘ 21 (mod 65)
6^4 β‘ 21 * 6 = 126 β‘ 61 (mod 65)
6^5 β‘ 61 * 6 = 366 β‘ 41 (mod 65)
6^6 β‘ 41 * 6 = 246 β‘ 51 (mod 65)
6^7 β‘ 51 * 6 = 306 β‘ 46 (mod 65)
Therefore d = 7 and the ciphertext for message 6 is 46. Final answer: d = 7, ciphertext = 46.
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