In a system an RSA algorithm with p = 5 and q = 11, is implemented for data security. What is the value of the decryption key if the value of the encryption key is 27 ?
In a system an RSA algorithm with p = 5 and q = 11, is implemented for data security. What is the value of the decryption key if the value of the encryption key is 27 ? Correct Answer 3
The correct answer is “option 1”.
CONCEPT:
RSA algorithm (Rivest-Shamir-Adleman) is an algorithm used by modern technologies to encrypt and decrypt messages.
It is asymmetric or public-key cryptography that uses two keys for encryption & decryption: Public key and private key.
[ alt="F1 Shraddha Raju 11.05.2021 D7" src="//storage.googleapis.com/tb-img/production/21/05/F1_Shraddha_Raju_11.05.2021_D7.png" style="width: 462px; height: 176px;">
Steps for RSA algorithm:
1. Choose two large prime numbers P & Q.
2. Find the product of chosen two numbers, N = P × Q
3. Calculate Euler’s totient (Φ) = (P - 1)(Q - 1)
4. Choose random integer e (public key) such that,
d x e = 1(mod Φ)
Where,
d is the private key.
6. Calculate Ciphertext C = mod n.
7. Calculate Plain text P = mod n.
CALCULATION:
Given two prime numbers are p = 5, q = 11
Product, n = 5 × 11 = 55
Φ = (5 - 1) × (11 - 1) = 40
e = 27,
d x 27 = 1 (mod 40)
d = 3
Hence, the correct answer is “option 1”.