In RSA 1. p and q are chosen as very large prime number 2. Compute n = p * q and ϕ(n) = (p-1) * (q-1) Later e encryption key chosen. How this encryption key is selected?

In RSA 1. p and q are chosen as very large prime number 2. Compute n = p * q and ϕ(n) = (p-1) * (q-1) Later e encryption key chosen. How this encryption key is selected? Correct Answer e is chosen as a relative prime to ϕ(n)

Concept:

RSA algorithm:

Step 1: Choose two distinct very large prime numbers p, q

Step 2: Compute n = p × q

Step 3: Compute ϕ(n) = (p-1) × (q-1)

Step 4: Choose an integer e, 1 <= e < ϕ(n) where e is co-prime to ϕ(n)

Step 5: Determine d as e × d = 1 mod ϕ(n)

Here (e, n) as private key or public key and (d, n) as public key or private key

In step 4 we can see that e is relative prime to ϕ(n) so option 1 is the correct answer.