private async Task Process(ServerHello m)
        {
            conn.SelectedCipherSuite = m.CipherSuite;

            if (m.KeyShare == null || m.KeyShare.Group != conn.MyKeyShare.Group)
            {
                return;
            }

            if (m.KeyShare.Group == Messages.Extensions.NamedGroup.secp256r1)
            {
                var sharedPub     = CryptoHelper.PublicKeyFromBytes(m.KeyShare.KeyExchange);
                var shared_secret = CryptoHelper.CalculateSharedKey(conn.MyKey, sharedPub);

                //var shared_secret = new byte[0]; //CryptoHelper.ComputeSha256Hash(ecdhe.DeriveKeyMaterial(theirKey));
                var hello_hash = conn.GetHashOfProcessedMessage();
                var zero_key   = "0000000000000000000000000000000000000000000000000000000000000000".ToByteArrayFromHex();

                AronParker.Hkdf.Hkdf hkdf = new AronParker.Hkdf.Hkdf(HashAlgorithmName.SHA256);

                var early_secret     = hkdf.Extract(zero_key, new byte[] { 0 });
                var empty_hash       = CryptoHelper.ComputeSha256Hash(new byte[] { });
                var derived_secret   = CryptoHelper.ExpandTLSLabel(hkdf, early_secret, CryptoHelper.DERIVED_LABEL, empty_hash, 32);
                var handshake_secret = hkdf.Extract(shared_secret, derived_secret);
                var client_handshake_traffic_secret = CryptoHelper.ExpandTLSLabel(hkdf, handshake_secret, CryptoHelper.CLIENT_HANDSHAKE_LABEL, hello_hash, 32);
                var server_handshake_traffic_secret = CryptoHelper.ExpandTLSLabel(hkdf, handshake_secret, CryptoHelper.SERVER_HANDSHAKE_LABEL, hello_hash, 32);

                //var masterKey = ecdhe.DeriveKeyTls(theirKey, MASTER_SECRET_LABEL, seed);
                //master_secret = PRF(premasterKey, "master secret", ClientHello.random + ServerHello.random)
                //var keyData = EncryptionKeys.Hkdf256.Expand(premasterKey, 96, seed);

                conn.CipherUpdated(new CipherUpdateDetail()
                {
                    State        = EncryptionState.Handshake,
                    ClientSecret = client_handshake_traffic_secret,
                    ServerSecret = server_handshake_traffic_secret,
                    CipherSuite  = conn.SelectedCipherSuite,
                });
            }

            await Task.Yield();
        }