Blockchain use RSA which involves a public key and a private key. The public key can be known to everyone and is used for encrypting messages. Messages encrypted with the public key can only be decrypted using the private key. The keys for the RSA algorithm are generated the following way:

Choose two distinct large random prime numbers p and q

Compute n=pq

• n is used as the modulus for both the public and private keys
• Compute the totient: phi(n)= (p-1)(q-1)

Choose an integer such that 1 < e

• e is released as the public key exponent

Compute d to satisfy the congruence relation de=1 mod (phi(n)) or as an example d = (e^(-1) mod phi(n))

• d is kept as the private key exponent

1. p = 11

q = 3

2. p = 23

q= 13