server: thread_rng is a CSPRNG, closes #508

src/server/mod.rs

@@ -197,7 +197,6 @@ impl Server {
         }
 
         let mut shared = [0; 16];
-        // TODO: is this cryptographically secure enough?
         rand::thread_rng().fill(&mut shared);
 
         let shared_e = rsa_public_encrypt_pkcs1::encrypt(&public_key, &shared).unwrap();