To speed up decryption Alice has chosen to set her private k

To speed up decryption, Alice has chosen to set her private key d = 3 and computes e as the inverse of d modulo t. Is this a good design decision?

Solution

Answer

It can be a good design only if it satisfies the below two conditions:

i. N = p*q (where p and q are very large prime numbers)

ii. e*d % ((p-1)*(q-1)) = 1