Are server nonce and client nonce in SSL equal?

Question

The explanation in the book is not clear that whether they are equal or not. My thought is below.

If they are equal, the server can not prevent replay attack because the nonce is determined by the client.

If they are not equal, then it seems that the server and client must compute Master secret twice, one with client nonce and one with server nonce

What is the exact implementation of SSL?

Answer 1

The nonces on the server and client side are created independently from each other. This means they are most likely not the same.

If they are not equal, then it seems that the server and client must compute Master secret twice, one with client nonce and one with server nonce

The master secret is computed by including both nonces since both nonces are known on both sides, one because it was created locally and the other one because it was received by the peer. For the details see TLS 1.2 section 8.1 Computing the Master Secret:

  master_secret = PRF(pre_master_secret, "master secret",
                      ClientHello.random + ServerHello.random)
                      [0..47];

ClientHello.random and ServerHello.random are what is called nonces in the document you refer to.