protected virtual void ReceiveClientHelloMessage(MemoryStream buf)
    {
        ProtocolVersion protocolVersion = TlsUtilities.ReadVersion(buf);

        mRecordStream.SetWriteVersion(protocolVersion);
        if (protocolVersion.IsDtls)
        {
            throw new TlsFatalAlert(47);
        }
        byte[] clientRandom = TlsUtilities.ReadFully(32, buf);
        byte[] array        = TlsUtilities.ReadOpaque8(buf);
        if (array.Length > 32)
        {
            throw new TlsFatalAlert(47);
        }
        int num = TlsUtilities.ReadUint16(buf);

        if (num < 2 || (num & 1) != 0)
        {
            throw new TlsFatalAlert(50);
        }
        mOfferedCipherSuites = TlsUtilities.ReadUint16Array(num / 2, buf);
        int num2 = TlsUtilities.ReadUint8(buf);

        if (num2 < 1)
        {
            throw new TlsFatalAlert(47);
        }
        mOfferedCompressionMethods = TlsUtilities.ReadUint8Array(num2, buf);
        mClientExtensions          = TlsProtocol.ReadExtensions(buf);
        mSecurityParameters.extendedMasterSecret = TlsExtensionsUtilities.HasExtendedMasterSecretExtension(mClientExtensions);
        ContextAdmin.SetClientVersion(protocolVersion);
        mTlsServer.NotifyClientVersion(protocolVersion);
        mTlsServer.NotifyFallback(Arrays.Contains(mOfferedCipherSuites, 22016));
        mSecurityParameters.clientRandom = clientRandom;
        mTlsServer.NotifyOfferedCipherSuites(mOfferedCipherSuites);
        mTlsServer.NotifyOfferedCompressionMethods(mOfferedCompressionMethods);
        if (Arrays.Contains(mOfferedCipherSuites, 255))
        {
            mSecureRenegotiation = true;
        }
        byte[] extensionData = TlsUtilities.GetExtensionData(mClientExtensions, 65281);
        if (extensionData != null)
        {
            mSecureRenegotiation = true;
            if (!Arrays.ConstantTimeAreEqual(extensionData, TlsProtocol.CreateRenegotiationInfo(TlsUtilities.EmptyBytes)))
            {
                throw new TlsFatalAlert(40);
            }
        }
        mTlsServer.NotifySecureRenegotiation(mSecureRenegotiation);
        if (mClientExtensions != null)
        {
            mTlsServer.ProcessClientExtensions(mClientExtensions);
        }
    }
        protected virtual void ProcessServerHello(ClientHandshakeState state, byte[] body)
        {
            SecurityParameters securityParameters = state.clientContext.SecurityParameters;

            MemoryStream buf = new MemoryStream(body, false);

            {
                ProtocolVersion server_version = TlsUtilities.ReadVersion(buf);
                ReportServerVersion(state, server_version);
            }

            securityParameters.serverRandom = TlsUtilities.ReadFully(32, buf);

            state.selectedSessionID = TlsUtilities.ReadOpaque8(buf);
            if (state.selectedSessionID.Length > 32)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }
            state.client.NotifySessionID(state.selectedSessionID);
            state.resumedSession = state.selectedSessionID.Length > 0 && state.tlsSession != null &&
                                   Arrays.AreEqual(state.selectedSessionID, state.tlsSession.SessionID);

            int selectedCipherSuite = TlsUtilities.ReadUint16(buf);

            if (!Arrays.Contains(state.offeredCipherSuites, selectedCipherSuite) ||
                selectedCipherSuite == CipherSuite.TLS_NULL_WITH_NULL_NULL ||
                CipherSuite.IsScsv(selectedCipherSuite) ||
                !TlsUtilities.IsValidCipherSuiteForVersion(selectedCipherSuite, state.clientContext.ServerVersion))
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }
            ValidateSelectedCipherSuite(selectedCipherSuite, AlertDescription.illegal_parameter);
            state.client.NotifySelectedCipherSuite(selectedCipherSuite);

            byte selectedCompressionMethod = TlsUtilities.ReadUint8(buf);

            if (CompressionMethod.cls_null != selectedCompressionMethod)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }
            state.client.NotifySelectedCompressionMethod(selectedCompressionMethod);

            /*
             * RFC3546 2.2 The extended server hello message format MAY be sent in place of the server
             * hello message when the client has requested extended functionality via the extended
             * client hello message specified in Section 2.1. ... Note that the extended server hello
             * message is only sent in response to an extended client hello message. This prevents the
             * possibility that the extended server hello message could "break" existing TLS 1.0
             * clients.
             */

            /*
             * TODO RFC 3546 2.3 If [...] the older session is resumed, then the server MUST ignore
             * extensions appearing in the client hello, and send a server hello containing no
             * extensions.
             */

            // Integer -> byte[]
            state.serverExtensions = TlsProtocol.ReadExtensions(buf);

            /*
             * RFC 7627 4. Clients and servers SHOULD NOT accept handshakes that do not use the extended
             * master secret [..]. (and see 5.2, 5.3)
             */
            securityParameters.extendedMasterSecret = TlsExtensionsUtilities.HasExtendedMasterSecretExtension(state.serverExtensions);

            if (!securityParameters.IsExtendedMasterSecret &&
                (state.resumedSession || state.client.RequiresExtendedMasterSecret()))
            {
                throw new TlsFatalAlert(AlertDescription.handshake_failure);
            }

            /*
             * RFC 3546 2.2 Note that the extended server hello message is only sent in response to an
             * extended client hello message. However, see RFC 5746 exception below. We always include
             * the SCSV, so an Extended Server Hello is always allowed.
             */
            if (state.serverExtensions != null)
            {
                foreach (int extType in state.serverExtensions.Keys)
                {
                    /*
                     * RFC 5746 3.6. Note that sending a "renegotiation_info" extension in response to a
                     * ClientHello containing only the SCSV is an explicit exception to the prohibition
                     * in RFC 5246, Section 7.4.1.4, on the server sending unsolicited extensions and is
                     * only allowed because the client is signaling its willingness to receive the
                     * extension via the TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV.
                     */
                    if (extType == ExtensionType.renegotiation_info)
                    {
                        continue;
                    }

                    /*
                     * RFC 5246 7.4.1.4 An extension type MUST NOT appear in the ServerHello unless the
                     * same extension type appeared in the corresponding ClientHello. If a client
                     * receives an extension type in ServerHello that it did not request in the
                     * associated ClientHello, it MUST abort the handshake with an unsupported_extension
                     * fatal alert.
                     */
                    if (null == TlsUtilities.GetExtensionData(state.clientExtensions, extType))
                    {
                        throw new TlsFatalAlert(AlertDescription.unsupported_extension);
                    }

                    /*
                     * RFC 3546 2.3. If [...] the older session is resumed, then the server MUST ignore
                     * extensions appearing in the client hello, and send a server hello containing no
                     * extensions[.]
                     */
                    if (state.resumedSession)
                    {
                        // TODO[compat-gnutls] GnuTLS test server sends server extensions e.g. ec_point_formats
                        // TODO[compat-openssl] OpenSSL test server sends server extensions e.g. ec_point_formats
                        // TODO[compat-polarssl] PolarSSL test server sends server extensions e.g. ec_point_formats
                        //throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                    }
                }
            }

            /*
             * RFC 5746 3.4. Client Behavior: Initial Handshake
             */
            {
                /*
                 * When a ServerHello is received, the client MUST check if it includes the
                 * "renegotiation_info" extension:
                 */
                byte[] renegExtData = TlsUtilities.GetExtensionData(state.serverExtensions, ExtensionType.renegotiation_info);
                if (renegExtData != null)
                {
                    /*
                     * If the extension is present, set the secure_renegotiation flag to TRUE. The
                     * client MUST then verify that the length of the "renegotiated_connection"
                     * field is zero, and if it is not, MUST abort the handshake (by sending a fatal
                     * handshake_failure alert).
                     */
                    state.secure_renegotiation = true;

                    if (!Arrays.ConstantTimeAreEqual(renegExtData, TlsProtocol.CreateRenegotiationInfo(TlsUtilities.EmptyBytes)))
                    {
                        throw new TlsFatalAlert(AlertDescription.handshake_failure);
                    }
                }
            }

            // TODO[compat-gnutls] GnuTLS test server fails to send renegotiation_info extension when resuming
            state.client.NotifySecureRenegotiation(state.secure_renegotiation);

            IDictionary sessionClientExtensions = state.clientExtensions, sessionServerExtensions = state.serverExtensions;

            if (state.resumedSession)
            {
                if (selectedCipherSuite != state.sessionParameters.CipherSuite ||
                    selectedCompressionMethod != state.sessionParameters.CompressionAlgorithm)
                {
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                }

                sessionClientExtensions = null;
                sessionServerExtensions = state.sessionParameters.ReadServerExtensions();
            }

            securityParameters.cipherSuite          = selectedCipherSuite;
            securityParameters.compressionAlgorithm = selectedCompressionMethod;

            if (sessionServerExtensions != null && sessionServerExtensions.Count > 0)
            {
                {
                    /*
                     * RFC 7366 3. If a server receives an encrypt-then-MAC request extension from a client
                     * and then selects a stream or Authenticated Encryption with Associated Data (AEAD)
                     * ciphersuite, it MUST NOT send an encrypt-then-MAC response extension back to the
                     * client.
                     */
                    bool serverSentEncryptThenMAC = TlsExtensionsUtilities.HasEncryptThenMacExtension(sessionServerExtensions);
                    if (serverSentEncryptThenMAC && !TlsUtilities.IsBlockCipherSuite(securityParameters.CipherSuite))
                    {
                        throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                    }
                    securityParameters.encryptThenMac = serverSentEncryptThenMAC;
                }

                securityParameters.maxFragmentLength = EvaluateMaxFragmentLengthExtension(state.resumedSession,
                                                                                          sessionClientExtensions, sessionServerExtensions, AlertDescription.illegal_parameter);

                securityParameters.truncatedHMac = TlsExtensionsUtilities.HasTruncatedHMacExtension(sessionServerExtensions);

                /*
                 * TODO It's surprising that there's no provision to allow a 'fresh' CertificateStatus to be
                 * sent in a session resumption handshake.
                 */
                state.allowCertificateStatus = !state.resumedSession &&
                                               TlsUtilities.HasExpectedEmptyExtensionData(sessionServerExtensions, ExtensionType.status_request,
                                                                                          AlertDescription.illegal_parameter);

                state.expectSessionTicket = !state.resumedSession &&
                                            TlsUtilities.HasExpectedEmptyExtensionData(sessionServerExtensions, ExtensionType.session_ticket,
                                                                                       AlertDescription.illegal_parameter);
            }

            if (sessionClientExtensions != null)
            {
                state.client.ProcessServerExtensions(sessionServerExtensions);
            }

            securityParameters.prfAlgorithm = TlsProtocol.GetPrfAlgorithm(state.clientContext,
                                                                          securityParameters.CipherSuite);

            /*
             * RFC 5246 7.4.9. Any cipher suite which does not explicitly specify verify_data_length has
             * a verify_data_length equal to 12. This includes all existing cipher suites.
             */
            securityParameters.verifyDataLength = 12;
        }
        protected virtual void ProcessClientHello(ServerHandshakeState state, byte[] body)
        {
            MemoryStream buf = new MemoryStream(body, false);

            // TODO Read RFCs for guidance on the expected record layer version number
            ProtocolVersion client_version = TlsUtilities.ReadVersion(buf);

            if (!client_version.IsDtls)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }

            /*
             * Read the client random
             */
            byte[] client_random = TlsUtilities.ReadFully(32, buf);

            byte[] sessionID = TlsUtilities.ReadOpaque8(buf);
            if (sessionID.Length > 32)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }

            // TODO RFC 4347 has the cookie length restricted to 32, but not in RFC 6347
            byte[] cookie = TlsUtilities.ReadOpaque8(buf);

            int cipher_suites_length = TlsUtilities.ReadUint16(buf);

            if (cipher_suites_length < 2 || (cipher_suites_length & 1) != 0)
            {
                throw new TlsFatalAlert(AlertDescription.decode_error);
            }

            /*
             * NOTE: "If the session_id field is not empty (implying a session resumption request) this
             * vector must include at least the cipher_suite from that session."
             */
            state.offeredCipherSuites = TlsUtilities.ReadUint16Array(cipher_suites_length / 2, buf);

            int compression_methods_length = TlsUtilities.ReadUint8(buf);

            if (compression_methods_length < 1)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }

            state.offeredCompressionMethods = TlsUtilities.ReadUint8Array(compression_methods_length, buf);

            /*
             * TODO RFC 3546 2.3 If [...] the older session is resumed, then the server MUST ignore
             * extensions appearing in the client hello, and send a server hello containing no
             * extensions.
             */
            state.clientExtensions = TlsProtocol.ReadExtensions(buf);

            TlsServerContextImpl context            = state.serverContext;
            SecurityParameters   securityParameters = context.SecurityParameters;

            /*
             * TODO[session-hash]
             *
             * draft-ietf-tls-session-hash-04 4. Clients and servers SHOULD NOT accept handshakes
             * that do not use the extended master secret [..]. (and see 5.2, 5.3)
             */
            securityParameters.extendedMasterSecret = TlsExtensionsUtilities.HasExtendedMasterSecretExtension(state.clientExtensions);

            context.SetClientVersion(client_version);

            state.server.NotifyClientVersion(client_version);
            state.server.NotifyFallback(Arrays.Contains(state.offeredCipherSuites, CipherSuite.TLS_FALLBACK_SCSV));

            securityParameters.clientRandom = client_random;

            state.server.NotifyOfferedCipherSuites(state.offeredCipherSuites);
            state.server.NotifyOfferedCompressionMethods(state.offeredCompressionMethods);

            /*
             * RFC 5746 3.6. Server Behavior: Initial Handshake
             */
            {
                /*
                 * RFC 5746 3.4. The client MUST include either an empty "renegotiation_info" extension,
                 * or the TLS_EMPTY_RENEGOTIATION_INFO_SCSV signaling cipher suite value in the
                 * ClientHello. Including both is NOT RECOMMENDED.
                 */

                /*
                 * When a ClientHello is received, the server MUST check if it includes the
                 * TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV. If it does, set the secure_renegotiation flag
                 * to TRUE.
                 */
                if (Arrays.Contains(state.offeredCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV))
                {
                    state.secure_renegotiation = true;
                }

                /*
                 * The server MUST check if the "renegotiation_info" extension is included in the
                 * ClientHello.
                 */
                byte[] renegExtData = TlsUtilities.GetExtensionData(state.clientExtensions, ExtensionType.renegotiation_info);
                if (renegExtData != null)
                {
                    /*
                     * If the extension is present, set secure_renegotiation flag to TRUE. The
                     * server MUST then verify that the length of the "renegotiated_connection"
                     * field is zero, and if it is not, MUST abort the handshake.
                     */
                    state.secure_renegotiation = true;

                    if (!Arrays.ConstantTimeAreEqual(renegExtData, TlsProtocol.CreateRenegotiationInfo(TlsUtilities.EmptyBytes)))
                    {
                        throw new TlsFatalAlert(AlertDescription.handshake_failure);
                    }
                }
            }

            state.server.NotifySecureRenegotiation(state.secure_renegotiation);

            if (state.clientExtensions != null)
            {
                state.server.ProcessClientExtensions(state.clientExtensions);
            }
        }
        protected virtual byte[] GenerateServerHello(ServerHandshakeState state)
        {
            SecurityParameters securityParameters = state.serverContext.SecurityParameters;

            MemoryStream buf = new MemoryStream();

            {
                ProtocolVersion server_version = state.server.GetServerVersion();
                if (!server_version.IsEqualOrEarlierVersionOf(state.serverContext.ClientVersion))
                {
                    throw new TlsFatalAlert(AlertDescription.internal_error);
                }

                // TODO Read RFCs for guidance on the expected record layer version number
                // recordStream.setReadVersion(server_version);
                // recordStream.setWriteVersion(server_version);
                // recordStream.setRestrictReadVersion(true);
                state.serverContext.SetServerVersion(server_version);

                TlsUtilities.WriteVersion(state.serverContext.ServerVersion, buf);
            }

            buf.Write(securityParameters.ServerRandom, 0, securityParameters.ServerRandom.Length);

            /*
             * The server may return an empty session_id to indicate that the session will not be cached
             * and therefore cannot be resumed.
             */
            TlsUtilities.WriteOpaque8(TlsUtilities.EmptyBytes, buf);

            int selectedCipherSuite = state.server.GetSelectedCipherSuite();

            if (!Arrays.Contains(state.offeredCipherSuites, selectedCipherSuite) ||
                selectedCipherSuite == CipherSuite.TLS_NULL_WITH_NULL_NULL ||
                CipherSuite.IsScsv(selectedCipherSuite) ||
                !TlsUtilities.IsValidCipherSuiteForVersion(selectedCipherSuite, state.serverContext.ServerVersion))
            {
                throw new TlsFatalAlert(AlertDescription.internal_error);
            }
            ValidateSelectedCipherSuite(selectedCipherSuite, AlertDescription.internal_error);
            securityParameters.cipherSuite = selectedCipherSuite;

            byte selectedCompressionMethod = state.server.GetSelectedCompressionMethod();

            if (!Arrays.Contains(state.offeredCompressionMethods, selectedCompressionMethod))
            {
                throw new TlsFatalAlert(AlertDescription.internal_error);
            }
            securityParameters.compressionAlgorithm = selectedCompressionMethod;

            TlsUtilities.WriteUint16(selectedCipherSuite, buf);
            TlsUtilities.WriteUint8(selectedCompressionMethod, buf);

            state.serverExtensions = state.server.GetServerExtensions();

            /*
             * RFC 5746 3.6. Server Behavior: Initial Handshake
             */
            if (state.secure_renegotiation)
            {
                byte[] renegExtData = TlsUtilities.GetExtensionData(state.serverExtensions, ExtensionType.renegotiation_info);
                bool   noRenegExt   = (null == renegExtData);

                if (noRenegExt)
                {
                    /*
                     * Note that sending a "renegotiation_info" extension in response to a ClientHello
                     * containing only the SCSV is an explicit exception to the prohibition in RFC 5246,
                     * Section 7.4.1.4, on the server sending unsolicited extensions and is only allowed
                     * because the client is signaling its willingness to receive the extension via the
                     * TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV.
                     */

                    /*
                     * If the secure_renegotiation flag is set to TRUE, the server MUST include an empty
                     * "renegotiation_info" extension in the ServerHello message.
                     */
                    state.serverExtensions = TlsExtensionsUtilities.EnsureExtensionsInitialised(state.serverExtensions);
                    state.serverExtensions[ExtensionType.renegotiation_info] = TlsProtocol.CreateRenegotiationInfo(TlsUtilities.EmptyBytes);
                }
            }

            if (securityParameters.extendedMasterSecret)
            {
                state.serverExtensions = TlsExtensionsUtilities.EnsureExtensionsInitialised(state.serverExtensions);
                TlsExtensionsUtilities.AddExtendedMasterSecretExtension(state.serverExtensions);
            }

            /*
             * TODO RFC 3546 2.3 If [...] the older session is resumed, then the server MUST ignore
             * extensions appearing in the client hello, and send a server hello containing no
             * extensions.
             */

            if (state.serverExtensions != null)
            {
                securityParameters.encryptThenMac = TlsExtensionsUtilities.HasEncryptThenMacExtension(state.serverExtensions);

                securityParameters.maxFragmentLength = EvaluateMaxFragmentLengthExtension(state.resumedSession,
                                                                                          state.clientExtensions, state.serverExtensions, AlertDescription.internal_error);

                securityParameters.truncatedHMac = TlsExtensionsUtilities.HasTruncatedHMacExtension(state.serverExtensions);

                /*
                 * TODO It's surprising that there's no provision to allow a 'fresh' CertificateStatus to be sent in
                 * a session resumption handshake.
                 */
                state.allowCertificateStatus = !state.resumedSession &&
                                               TlsUtilities.HasExpectedEmptyExtensionData(state.serverExtensions, ExtensionType.status_request,
                                                                                          AlertDescription.internal_error);

                state.expectSessionTicket = !state.resumedSession &&
                                            TlsUtilities.HasExpectedEmptyExtensionData(state.serverExtensions, ExtensionType.session_ticket,
                                                                                       AlertDescription.internal_error);

                TlsProtocol.WriteExtensions(buf, state.serverExtensions);
            }

            securityParameters.prfAlgorithm = TlsProtocol.GetPrfAlgorithm(state.serverContext,
                                                                          securityParameters.CipherSuite);

            /*
             * RFC 5264 7.4.9. Any cipher suite which does not explicitly specify verify_data_length
             * has a verify_data_length equal to 12. This includes all existing cipher suites.
             */
            securityParameters.verifyDataLength = 12;

            return(buf.ToArray());
        }
    protected virtual void SendServerHelloMessage()
    {
        HandshakeMessage handshakeMessage = new HandshakeMessage(2);
        ProtocolVersion  serverVersion    = mTlsServer.GetServerVersion();

        if (!serverVersion.IsEqualOrEarlierVersionOf(Context.ClientVersion))
        {
            throw new TlsFatalAlert(80);
        }
        mRecordStream.ReadVersion = serverVersion;
        mRecordStream.SetWriteVersion(serverVersion);
        mRecordStream.SetRestrictReadVersion(enabled: true);
        ContextAdmin.SetServerVersion(serverVersion);
        TlsUtilities.WriteVersion(serverVersion, handshakeMessage);
        handshakeMessage.Write(mSecurityParameters.serverRandom);
        TlsUtilities.WriteOpaque8(TlsUtilities.EmptyBytes, handshakeMessage);
        int selectedCipherSuite = mTlsServer.GetSelectedCipherSuite();

        if (!Arrays.Contains(mOfferedCipherSuites, selectedCipherSuite) || selectedCipherSuite == 0 || CipherSuite.IsScsv(selectedCipherSuite) || !TlsUtilities.IsValidCipherSuiteForVersion(selectedCipherSuite, Context.ServerVersion))
        {
            throw new TlsFatalAlert(80);
        }
        mSecurityParameters.cipherSuite = selectedCipherSuite;
        byte selectedCompressionMethod = mTlsServer.GetSelectedCompressionMethod();

        if (!Arrays.Contains(mOfferedCompressionMethods, selectedCompressionMethod))
        {
            throw new TlsFatalAlert(80);
        }
        mSecurityParameters.compressionAlgorithm = selectedCompressionMethod;
        TlsUtilities.WriteUint16(selectedCipherSuite, handshakeMessage);
        TlsUtilities.WriteUint8(selectedCompressionMethod, handshakeMessage);
        mServerExtensions = mTlsServer.GetServerExtensions();
        if (mSecureRenegotiation)
        {
            byte[] extensionData = TlsUtilities.GetExtensionData(mServerExtensions, 65281);
            if (null == extensionData)
            {
                mServerExtensions        = TlsExtensionsUtilities.EnsureExtensionsInitialised(mServerExtensions);
                mServerExtensions[65281] = TlsProtocol.CreateRenegotiationInfo(TlsUtilities.EmptyBytes);
            }
        }
        if (mSecurityParameters.extendedMasterSecret)
        {
            mServerExtensions = TlsExtensionsUtilities.EnsureExtensionsInitialised(mServerExtensions);
            TlsExtensionsUtilities.AddExtendedMasterSecretExtension(mServerExtensions);
        }
        if (mServerExtensions != null)
        {
            mSecurityParameters.encryptThenMac    = TlsExtensionsUtilities.HasEncryptThenMacExtension(mServerExtensions);
            mSecurityParameters.maxFragmentLength = ProcessMaxFragmentLengthExtension(mClientExtensions, mServerExtensions, 80);
            mSecurityParameters.truncatedHMac     = TlsExtensionsUtilities.HasTruncatedHMacExtension(mServerExtensions);
            mAllowCertificateStatus = (!mResumedSession && TlsUtilities.HasExpectedEmptyExtensionData(mServerExtensions, 5, 80));
            mExpectSessionTicket    = (!mResumedSession && TlsUtilities.HasExpectedEmptyExtensionData(mServerExtensions, 35, 80));
            TlsProtocol.WriteExtensions(handshakeMessage, mServerExtensions);
        }
        mSecurityParameters.prfAlgorithm     = TlsProtocol.GetPrfAlgorithm(Context, mSecurityParameters.CipherSuite);
        mSecurityParameters.verifyDataLength = 12;
        ApplyMaxFragmentLengthExtension();
        handshakeMessage.WriteToRecordStream(this);
    }