RSA : The Process

Question 1

What type of cipher is RSA?

Answer 1

Block cipher.

Question 2

Why is RSA so secure?

Answer 2

Due to the infeasibility of factorising large prime numbers.

Question 3

What is the standard key length used in RSA?

Answer 3

2048 to 4096.

Question 4

What are the 5 steps of the RSA?

Answer 4

1. Pick 2 large prime numbers (P and Q).
2. Find N (N = P*Q), find Eu (Eu = (P-1)(Q-1)).
3. Choose e (public key) - 0 < e < Eu and e and Eu are co-primes (hcf is 1).
4. Calculate D via the multiplicative inverse of e -> d = (e^-1) mod Eu
   We now have (e,n) and (d,n).
5. Encrypt and decypt : C = (P^e) mod N; P = (C^d) mod N.