SetWriteVersion() приватный Метод

private SetWriteVersion ( Org.BouncyCastle.Crypto.Tls.ProtocolVersion writeVersion ) : void
writeVersion Org.BouncyCastle.Crypto.Tls.ProtocolVersion
Результат void
Пример #1
0
        internal virtual DtlsTransport ServerHandshake(ServerHandshakeState state, DtlsRecordLayer recordLayer)
        {
            SecurityParameters    securityParameters = state.serverContext.SecurityParameters;
            DtlsReliableHandshake handshake          = new DtlsReliableHandshake(state.serverContext, recordLayer);

            DtlsReliableHandshake.Message clientMessage = handshake.ReceiveMessage();

            // NOTE: DTLSRecordLayer requires any DTLS version, we don't otherwise constrain this
            //ProtocolVersion recordLayerVersion = recordLayer.ReadVersion;

            if (clientMessage.Type == HandshakeType.client_hello)
            {
                ProcessClientHello(state, clientMessage.Body);
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            {
                byte[] serverHelloBody = GenerateServerHello(state);

                ApplyMaxFragmentLengthExtension(recordLayer, securityParameters.maxFragmentLength);

                ProtocolVersion recordLayerVersion = state.serverContext.ServerVersion;
                recordLayer.ReadVersion = recordLayerVersion;
                recordLayer.SetWriteVersion(recordLayerVersion);

                handshake.SendMessage(HandshakeType.server_hello, serverHelloBody);
            }

            handshake.NotifyHelloComplete();

            IList serverSupplementalData = state.server.GetServerSupplementalData();

            if (serverSupplementalData != null)
            {
                byte[] supplementalDataBody = GenerateSupplementalData(serverSupplementalData);
                handshake.SendMessage(HandshakeType.supplemental_data, supplementalDataBody);
            }

            state.keyExchange = state.server.GetKeyExchange();
            state.keyExchange.Init(state.serverContext);

            state.serverCredentials = state.server.GetCredentials();

            Certificate serverCertificate = null;

            if (state.serverCredentials == null)
            {
                state.keyExchange.SkipServerCredentials();
            }
            else
            {
                state.keyExchange.ProcessServerCredentials(state.serverCredentials);

                serverCertificate = state.serverCredentials.Certificate;
                byte[] certificateBody = GenerateCertificate(serverCertificate);
                handshake.SendMessage(HandshakeType.certificate, certificateBody);
            }

            // TODO[RFC 3546] Check whether empty certificates is possible, allowed, or excludes CertificateStatus
            if (serverCertificate == null || serverCertificate.IsEmpty)
            {
                state.allowCertificateStatus = false;
            }

            if (state.allowCertificateStatus)
            {
                CertificateStatus certificateStatus = state.server.GetCertificateStatus();
                if (certificateStatus != null)
                {
                    byte[] certificateStatusBody = GenerateCertificateStatus(state, certificateStatus);
                    handshake.SendMessage(HandshakeType.certificate_status, certificateStatusBody);
                }
            }

            byte[] serverKeyExchange = state.keyExchange.GenerateServerKeyExchange();
            if (serverKeyExchange != null)
            {
                handshake.SendMessage(HandshakeType.server_key_exchange, serverKeyExchange);
            }

            if (state.serverCredentials != null)
            {
                state.certificateRequest = state.server.GetCertificateRequest();
                if (state.certificateRequest != null)
                {
                    if (TlsUtilities.IsTlsV12(state.serverContext) != (state.certificateRequest.SupportedSignatureAlgorithms != null))
                    {
                        throw new TlsFatalAlert(AlertDescription.internal_error);
                    }

                    state.keyExchange.ValidateCertificateRequest(state.certificateRequest);

                    byte[] certificateRequestBody = GenerateCertificateRequest(state, state.certificateRequest);
                    handshake.SendMessage(HandshakeType.certificate_request, certificateRequestBody);

                    TlsUtilities.TrackHashAlgorithms(handshake.HandshakeHash,
                                                     state.certificateRequest.SupportedSignatureAlgorithms);
                }
            }

            handshake.SendMessage(HandshakeType.server_hello_done, TlsUtilities.EmptyBytes);

            handshake.HandshakeHash.SealHashAlgorithms();

            clientMessage = handshake.ReceiveMessage();

            if (clientMessage.Type == HandshakeType.supplemental_data)
            {
                ProcessClientSupplementalData(state, clientMessage.Body);
                clientMessage = handshake.ReceiveMessage();
            }
            else
            {
                state.server.ProcessClientSupplementalData(null);
            }

            if (state.certificateRequest == null)
            {
                state.keyExchange.SkipClientCredentials();
            }
            else
            {
                if (clientMessage.Type == HandshakeType.certificate)
                {
                    ProcessClientCertificate(state, clientMessage.Body);
                    clientMessage = handshake.ReceiveMessage();
                }
                else
                {
                    if (TlsUtilities.IsTlsV12(state.serverContext))
                    {
                        /*
                         * RFC 5246 If no suitable certificate is available, the client MUST send a
                         * certificate message containing no certificates.
                         *
                         * NOTE: In previous RFCs, this was SHOULD instead of MUST.
                         */
                        throw new TlsFatalAlert(AlertDescription.unexpected_message);
                    }

                    NotifyClientCertificate(state, Certificate.EmptyChain);
                }
            }

            if (clientMessage.Type == HandshakeType.client_key_exchange)
            {
                ProcessClientKeyExchange(state, clientMessage.Body);
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            TlsHandshakeHash prepareFinishHash = handshake.PrepareToFinish();

            securityParameters.sessionHash = TlsProtocol.GetCurrentPrfHash(state.serverContext, prepareFinishHash, null);

            TlsProtocol.EstablishMasterSecret(state.serverContext, state.keyExchange);
            recordLayer.InitPendingEpoch(state.server.GetCipher());

            /*
             * RFC 5246 7.4.8 This message is only sent following a client certificate that has signing
             * capability (i.e., all certificates except those containing fixed Diffie-Hellman
             * parameters).
             */
            if (ExpectCertificateVerifyMessage(state))
            {
                byte[] certificateVerifyBody = handshake.ReceiveMessageBody(HandshakeType.certificate_verify);
                ProcessCertificateVerify(state, certificateVerifyBody, prepareFinishHash);
            }

            // NOTE: Calculated exclusive of the actual Finished message from the client
            byte[] expectedClientVerifyData = TlsUtilities.CalculateVerifyData(state.serverContext, ExporterLabel.client_finished,
                                                                               TlsProtocol.GetCurrentPrfHash(state.serverContext, handshake.HandshakeHash, null));
            ProcessFinished(handshake.ReceiveMessageBody(HandshakeType.finished), expectedClientVerifyData);

            if (state.expectSessionTicket)
            {
                NewSessionTicket newSessionTicket     = state.server.GetNewSessionTicket();
                byte[]           newSessionTicketBody = GenerateNewSessionTicket(state, newSessionTicket);
                handshake.SendMessage(HandshakeType.session_ticket, newSessionTicketBody);
            }

            // NOTE: Calculated exclusive of the Finished message itself
            byte[] serverVerifyData = TlsUtilities.CalculateVerifyData(state.serverContext, ExporterLabel.server_finished,
                                                                       TlsProtocol.GetCurrentPrfHash(state.serverContext, handshake.HandshakeHash, null));
            handshake.SendMessage(HandshakeType.finished, serverVerifyData);

            handshake.Finish();

            state.server.NotifyHandshakeComplete();

            return(new DtlsTransport(recordLayer));
        }
Пример #2
0
        internal virtual DtlsTransport ClientHandshake(ClientHandshakeState state, DtlsRecordLayer recordLayer)
        {
            SecurityParameters    securityParameters = state.clientContext.SecurityParameters;
            DtlsReliableHandshake handshake          = new DtlsReliableHandshake(state.clientContext, recordLayer);

            byte[] clientHelloBody = GenerateClientHello(state, state.client);

            recordLayer.SetWriteVersion(ProtocolVersion.DTLSv10);

            handshake.SendMessage(HandshakeType.client_hello, clientHelloBody);

            DtlsReliableHandshake.Message serverMessage = handshake.ReceiveMessage();

            while (serverMessage.Type == HandshakeType.hello_verify_request)
            {
                ProtocolVersion recordLayerVersion = recordLayer.ReadVersion;
                ProtocolVersion client_version     = state.clientContext.ClientVersion;

                /*
                 * RFC 6347 4.2.1 DTLS 1.2 server implementations SHOULD use DTLS version 1.0 regardless of
                 * the version of TLS that is expected to be negotiated. DTLS 1.2 and 1.0 clients MUST use
                 * the version solely to indicate packet formatting (which is the same in both DTLS 1.2 and
                 * 1.0) and not as part of version negotiation.
                 */
                if (!recordLayerVersion.IsEqualOrEarlierVersionOf(client_version))
                {
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                }

                recordLayer.ReadVersion = null;

                byte[] cookie  = ProcessHelloVerifyRequest(state, serverMessage.Body);
                byte[] patched = PatchClientHelloWithCookie(clientHelloBody, cookie);

                handshake.ResetHandshakeMessagesDigest();
                handshake.SendMessage(HandshakeType.client_hello, patched);

                serverMessage = handshake.ReceiveMessage();
            }

            if (serverMessage.Type == HandshakeType.server_hello)
            {
                ProtocolVersion recordLayerVersion = recordLayer.ReadVersion;
                ReportServerVersion(state, recordLayerVersion);
                recordLayer.SetWriteVersion(recordLayerVersion);

                ProcessServerHello(state, serverMessage.Body);
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            handshake.NotifyHelloComplete();

            ApplyMaxFragmentLengthExtension(recordLayer, securityParameters.maxFragmentLength);

            if (state.resumedSession)
            {
                securityParameters.masterSecret = Arrays.Clone(state.sessionParameters.MasterSecret);
                recordLayer.InitPendingEpoch(state.client.GetCipher());

                // NOTE: Calculated exclusive of the actual Finished message from the server
                byte[] resExpectedServerVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.server_finished,
                                                                                      TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
                ProcessFinished(handshake.ReceiveMessageBody(HandshakeType.finished), resExpectedServerVerifyData);

                // NOTE: Calculated exclusive of the Finished message itself
                byte[] resClientVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.client_finished,
                                                                              TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
                handshake.SendMessage(HandshakeType.finished, resClientVerifyData);

                handshake.Finish();

                state.clientContext.SetResumableSession(state.tlsSession);

                state.client.NotifyHandshakeComplete();

                return(new DtlsTransport(recordLayer));
            }

            InvalidateSession(state);

            if (state.selectedSessionID.Length > 0)
            {
                state.tlsSession = new TlsSessionImpl(state.selectedSessionID, null);
            }

            serverMessage = handshake.ReceiveMessage();

            if (serverMessage.Type == HandshakeType.supplemental_data)
            {
                ProcessServerSupplementalData(state, serverMessage.Body);
                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                state.client.ProcessServerSupplementalData(null);
            }

            state.keyExchange = state.client.GetKeyExchange();
            state.keyExchange.Init(state.clientContext);

            Certificate serverCertificate = null;

            if (serverMessage.Type == HandshakeType.certificate)
            {
                serverCertificate = ProcessServerCertificate(state, serverMessage.Body);
                serverMessage     = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, Certificate is optional
                state.keyExchange.SkipServerCredentials();
            }

            // TODO[RFC 3546] Check whether empty certificates is possible, allowed, or excludes CertificateStatus
            if (serverCertificate == null || serverCertificate.IsEmpty)
            {
                state.allowCertificateStatus = false;
            }

            if (serverMessage.Type == HandshakeType.certificate_status)
            {
                ProcessCertificateStatus(state, serverMessage.Body);
                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, CertificateStatus is optional
            }

            if (serverMessage.Type == HandshakeType.server_key_exchange)
            {
                ProcessServerKeyExchange(state, serverMessage.Body);
                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, ServerKeyExchange is optional
                state.keyExchange.SkipServerKeyExchange();
            }

            if (serverMessage.Type == HandshakeType.certificate_request)
            {
                ProcessCertificateRequest(state, serverMessage.Body);

                /*
                 * TODO Give the client a chance to immediately select the CertificateVerify hash
                 * algorithm here to avoid tracking the other hash algorithms unnecessarily?
                 */
                TlsUtilities.TrackHashAlgorithms(handshake.HandshakeHash,
                                                 state.certificateRequest.SupportedSignatureAlgorithms);

                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, CertificateRequest is optional
            }

            if (serverMessage.Type == HandshakeType.server_hello_done)
            {
                if (serverMessage.Body.Length != 0)
                {
                    throw new TlsFatalAlert(AlertDescription.decode_error);
                }
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            handshake.HandshakeHash.SealHashAlgorithms();

            IList clientSupplementalData = state.client.GetClientSupplementalData();

            if (clientSupplementalData != null)
            {
                byte[] supplementalDataBody = GenerateSupplementalData(clientSupplementalData);
                handshake.SendMessage(HandshakeType.supplemental_data, supplementalDataBody);
            }

            if (state.certificateRequest != null)
            {
                state.clientCredentials = state.authentication.GetClientCredentials(state.certificateRequest);

                /*
                 * RFC 5246 If no suitable certificate is available, the client MUST send a certificate
                 * message containing no certificates.
                 *
                 * NOTE: In previous RFCs, this was SHOULD instead of MUST.
                 */
                Certificate clientCertificate = null;
                if (state.clientCredentials != null)
                {
                    clientCertificate = state.clientCredentials.Certificate;
                }
                if (clientCertificate == null)
                {
                    clientCertificate = Certificate.EmptyChain;
                }

                byte[] certificateBody = GenerateCertificate(clientCertificate);
                handshake.SendMessage(HandshakeType.certificate, certificateBody);
            }

            if (state.clientCredentials != null)
            {
                state.keyExchange.ProcessClientCredentials(state.clientCredentials);
            }
            else
            {
                state.keyExchange.SkipClientCredentials();
            }

            byte[] clientKeyExchangeBody = GenerateClientKeyExchange(state);
            handshake.SendMessage(HandshakeType.client_key_exchange, clientKeyExchangeBody);

            TlsHandshakeHash prepareFinishHash = handshake.PrepareToFinish();

            securityParameters.sessionHash = TlsProtocol.GetCurrentPrfHash(state.clientContext, prepareFinishHash, null);

            TlsProtocol.EstablishMasterSecret(state.clientContext, state.keyExchange);
            recordLayer.InitPendingEpoch(state.client.GetCipher());

            if (state.clientCredentials != null && state.clientCredentials is TlsSignerCredentials)
            {
                TlsSignerCredentials signerCredentials = (TlsSignerCredentials)state.clientCredentials;

                /*
                 * RFC 5246 4.7. digitally-signed element needs SignatureAndHashAlgorithm from TLS 1.2
                 */
                SignatureAndHashAlgorithm signatureAndHashAlgorithm = TlsUtilities.GetSignatureAndHashAlgorithm(
                    state.clientContext, signerCredentials);

                byte[] hash;
                if (signatureAndHashAlgorithm == null)
                {
                    hash = securityParameters.SessionHash;
                }
                else
                {
                    hash = prepareFinishHash.GetFinalHash(signatureAndHashAlgorithm.Hash);
                }

                byte[]          signature             = signerCredentials.GenerateCertificateSignature(hash);
                DigitallySigned certificateVerify     = new DigitallySigned(signatureAndHashAlgorithm, signature);
                byte[]          certificateVerifyBody = GenerateCertificateVerify(state, certificateVerify);
                handshake.SendMessage(HandshakeType.certificate_verify, certificateVerifyBody);
            }

            // NOTE: Calculated exclusive of the Finished message itself
            byte[] clientVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.client_finished,
                                                                       TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
            handshake.SendMessage(HandshakeType.finished, clientVerifyData);

            if (state.expectSessionTicket)
            {
                serverMessage = handshake.ReceiveMessage();
                if (serverMessage.Type == HandshakeType.session_ticket)
                {
                    ProcessNewSessionTicket(state, serverMessage.Body);
                }
                else
                {
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }
            }

            // NOTE: Calculated exclusive of the actual Finished message from the server
            byte[] expectedServerVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.server_finished,
                                                                               TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
            ProcessFinished(handshake.ReceiveMessageBody(HandshakeType.finished), expectedServerVerifyData);

            handshake.Finish();

            if (state.tlsSession != null)
            {
                state.sessionParameters = new SessionParameters.Builder()
                                          .SetCipherSuite(securityParameters.CipherSuite)
                                          .SetCompressionAlgorithm(securityParameters.CompressionAlgorithm)
                                          .SetMasterSecret(securityParameters.MasterSecret)
                                          .SetPeerCertificate(serverCertificate)
                                          .SetPskIdentity(securityParameters.PskIdentity)
                                          .SetSrpIdentity(securityParameters.SrpIdentity)
                                          // TODO Consider filtering extensions that aren't relevant to resumed sessions
                                          .SetServerExtensions(state.serverExtensions)
                                          .Build();

                state.tlsSession = TlsUtilities.ImportSession(state.tlsSession.SessionID, state.sessionParameters);

                state.clientContext.SetResumableSession(state.tlsSession);
            }

            state.client.NotifyHandshakeComplete();

            return(new DtlsTransport(recordLayer));
        }
Пример #3
0
        internal virtual DtlsTransport ServerHandshake(ServerHandshakeState state, DtlsRecordLayer recordLayer)
        {
            SecurityParameters    securityParameters    = state.serverContext.SecurityParameters;
            DtlsReliableHandshake dtlsReliableHandshake = new DtlsReliableHandshake(state.serverContext, recordLayer);

            DtlsReliableHandshake.Message message = dtlsReliableHandshake.ReceiveMessage();
            if (message.Type == 1)
            {
                ProcessClientHello(state, message.Body);
                byte[] body = GenerateServerHello(state);
                DtlsProtocol.ApplyMaxFragmentLengthExtension(recordLayer, securityParameters.maxFragmentLength);
                ProtocolVersion writeVersion = (recordLayer.ReadVersion = state.serverContext.ServerVersion);
                recordLayer.SetWriteVersion(writeVersion);
                dtlsReliableHandshake.SendMessage(2, body);
                dtlsReliableHandshake.NotifyHelloComplete();
                global::System.Collections.IList serverSupplementalData = state.server.GetServerSupplementalData();
                if (serverSupplementalData != null)
                {
                    byte[] body2 = DtlsProtocol.GenerateSupplementalData(serverSupplementalData);
                    dtlsReliableHandshake.SendMessage(23, body2);
                }
                state.keyExchange = state.server.GetKeyExchange();
                state.keyExchange.Init(state.serverContext);
                state.serverCredentials = state.server.GetCredentials();
                Certificate certificate = null;
                if (state.serverCredentials == null)
                {
                    state.keyExchange.SkipServerCredentials();
                }
                else
                {
                    state.keyExchange.ProcessServerCredentials(state.serverCredentials);
                    certificate = state.serverCredentials.Certificate;
                    byte[] body3 = DtlsProtocol.GenerateCertificate(certificate);
                    dtlsReliableHandshake.SendMessage(11, body3);
                }
                if (certificate == null || certificate.IsEmpty)
                {
                    state.allowCertificateStatus = false;
                }
                if (state.allowCertificateStatus)
                {
                    CertificateStatus certificateStatus = state.server.GetCertificateStatus();
                    if (certificateStatus != null)
                    {
                        byte[] body4 = GenerateCertificateStatus(state, certificateStatus);
                        dtlsReliableHandshake.SendMessage(22, body4);
                    }
                }
                byte[] array = state.keyExchange.GenerateServerKeyExchange();
                if (array != null)
                {
                    dtlsReliableHandshake.SendMessage(12, array);
                }
                if (state.serverCredentials != null)
                {
                    state.certificateRequest = state.server.GetCertificateRequest();
                    if (state.certificateRequest != null)
                    {
                        if (TlsUtilities.IsTlsV12(state.serverContext) != (state.certificateRequest.SupportedSignatureAlgorithms != null))
                        {
                            throw new TlsFatalAlert(80);
                        }
                        state.keyExchange.ValidateCertificateRequest(state.certificateRequest);
                        byte[] body5 = GenerateCertificateRequest(state, state.certificateRequest);
                        dtlsReliableHandshake.SendMessage(13, body5);
                        TlsUtilities.TrackHashAlgorithms(dtlsReliableHandshake.HandshakeHash, state.certificateRequest.SupportedSignatureAlgorithms);
                    }
                }
                dtlsReliableHandshake.SendMessage(14, TlsUtilities.EmptyBytes);
                dtlsReliableHandshake.HandshakeHash.SealHashAlgorithms();
                message = dtlsReliableHandshake.ReceiveMessage();
                if (message.Type == 23)
                {
                    ProcessClientSupplementalData(state, message.Body);
                    message = dtlsReliableHandshake.ReceiveMessage();
                }
                else
                {
                    state.server.ProcessClientSupplementalData(null);
                }
                if (state.certificateRequest == null)
                {
                    state.keyExchange.SkipClientCredentials();
                }
                else if (message.Type == 11)
                {
                    ProcessClientCertificate(state, message.Body);
                    message = dtlsReliableHandshake.ReceiveMessage();
                }
                else
                {
                    if (TlsUtilities.IsTlsV12(state.serverContext))
                    {
                        throw new TlsFatalAlert(10);
                    }
                    NotifyClientCertificate(state, Certificate.EmptyChain);
                }
                if (message.Type == 16)
                {
                    ProcessClientKeyExchange(state, message.Body);
                    TlsHandshakeHash tlsHandshakeHash = dtlsReliableHandshake.PrepareToFinish();
                    securityParameters.sessionHash = TlsProtocol.GetCurrentPrfHash(state.serverContext, tlsHandshakeHash, null);
                    TlsProtocol.EstablishMasterSecret(state.serverContext, state.keyExchange);
                    recordLayer.InitPendingEpoch(state.server.GetCipher());
                    if (ExpectCertificateVerifyMessage(state))
                    {
                        byte[] body6 = dtlsReliableHandshake.ReceiveMessageBody(15);
                        ProcessCertificateVerify(state, body6, tlsHandshakeHash);
                    }
                    byte[] expected_verify_data = TlsUtilities.CalculateVerifyData(state.serverContext, "client finished", TlsProtocol.GetCurrentPrfHash(state.serverContext, dtlsReliableHandshake.HandshakeHash, null));
                    ProcessFinished(dtlsReliableHandshake.ReceiveMessageBody(20), expected_verify_data);
                    if (state.expectSessionTicket)
                    {
                        NewSessionTicket newSessionTicket = state.server.GetNewSessionTicket();
                        byte[]           body7            = GenerateNewSessionTicket(state, newSessionTicket);
                        dtlsReliableHandshake.SendMessage(4, body7);
                    }
                    byte[] body8 = TlsUtilities.CalculateVerifyData(state.serverContext, "server finished", TlsProtocol.GetCurrentPrfHash(state.serverContext, dtlsReliableHandshake.HandshakeHash, null));
                    dtlsReliableHandshake.SendMessage(20, body8);
                    dtlsReliableHandshake.Finish();
                    state.server.NotifyHandshakeComplete();
                    return(new DtlsTransport(recordLayer));
                }
                throw new TlsFatalAlert(10);
            }
            throw new TlsFatalAlert(10);
        }
Пример #4
0
        internal virtual DtlsTransport ServerHandshake(ServerHandshakeState state, DtlsRecordLayer recordLayer)
        {
            SecurityParameters securityParameters = state.serverContext.SecurityParameters;
            DtlsReliableHandshake handshake = new DtlsReliableHandshake(state.serverContext, recordLayer);

            DtlsReliableHandshake.Message clientMessage = handshake.ReceiveMessage();

            // NOTE: DTLSRecordLayer requires any DTLS version, we don't otherwise constrain this
            //ProtocolVersion recordLayerVersion = recordLayer.ReadVersion;

            if (clientMessage.Type == HandshakeType.client_hello)
            {
                ProcessClientHello(state, clientMessage.Body);
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            {
                byte[] serverHelloBody = GenerateServerHello(state);

                ApplyMaxFragmentLengthExtension(recordLayer, securityParameters.maxFragmentLength);

                ProtocolVersion recordLayerVersion = state.serverContext.ServerVersion;
                recordLayer.ReadVersion = recordLayerVersion;
                recordLayer.SetWriteVersion(recordLayerVersion);

                handshake.SendMessage(HandshakeType.server_hello, serverHelloBody);
            }

            handshake.NotifyHelloComplete();

            IList serverSupplementalData = state.server.GetServerSupplementalData();
            if (serverSupplementalData != null)
            {
                byte[] supplementalDataBody = GenerateSupplementalData(serverSupplementalData);
                handshake.SendMessage(HandshakeType.supplemental_data, supplementalDataBody);
            }

            state.keyExchange = state.server.GetKeyExchange();
            state.keyExchange.Init(state.serverContext);

            state.serverCredentials = state.server.GetCredentials();

            Certificate serverCertificate = null;

            if (state.serverCredentials == null)
            {
                state.keyExchange.SkipServerCredentials();
            }
            else
            {
                state.keyExchange.ProcessServerCredentials(state.serverCredentials);

                serverCertificate = state.serverCredentials.Certificate;
                byte[] certificateBody = GenerateCertificate(serverCertificate);
                handshake.SendMessage(HandshakeType.certificate, certificateBody);
            }

            // TODO[RFC 3546] Check whether empty certificates is possible, allowed, or excludes CertificateStatus
            if (serverCertificate == null || serverCertificate.IsEmpty)
            {
                state.allowCertificateStatus = false;
            }

            if (state.allowCertificateStatus)
            {
                CertificateStatus certificateStatus = state.server.GetCertificateStatus();
                if (certificateStatus != null)
                {
                    byte[] certificateStatusBody = GenerateCertificateStatus(state, certificateStatus);
                    handshake.SendMessage(HandshakeType.certificate_status, certificateStatusBody);
                }
            }

            byte[] serverKeyExchange = state.keyExchange.GenerateServerKeyExchange();
            if (serverKeyExchange != null)
            {
                handshake.SendMessage(HandshakeType.server_key_exchange, serverKeyExchange);
            }

            if (state.serverCredentials != null)
            {
                state.certificateRequest = state.server.GetCertificateRequest();
                if (state.certificateRequest != null)
                {
                    if (TlsUtilities.IsTlsV12(state.serverContext) != (state.certificateRequest.SupportedSignatureAlgorithms != null))
                        throw new TlsFatalAlert(AlertDescription.internal_error);

                    state.keyExchange.ValidateCertificateRequest(state.certificateRequest);

                    byte[] certificateRequestBody = GenerateCertificateRequest(state, state.certificateRequest);
                    handshake.SendMessage(HandshakeType.certificate_request, certificateRequestBody);

                    TlsUtilities.TrackHashAlgorithms(handshake.HandshakeHash,
                        state.certificateRequest.SupportedSignatureAlgorithms);
                }
            }

            handshake.SendMessage(HandshakeType.server_hello_done, TlsUtilities.EmptyBytes);

            handshake.HandshakeHash.SealHashAlgorithms();

            clientMessage = handshake.ReceiveMessage();

            if (clientMessage.Type == HandshakeType.supplemental_data)
            {
                ProcessClientSupplementalData(state, clientMessage.Body);
                clientMessage = handshake.ReceiveMessage();
            }
            else
            {
                state.server.ProcessClientSupplementalData(null);
            }

            if (state.certificateRequest == null)
            {
                state.keyExchange.SkipClientCredentials();
            }
            else
            {
                if (clientMessage.Type == HandshakeType.certificate)
                {
                    ProcessClientCertificate(state, clientMessage.Body);
                    clientMessage = handshake.ReceiveMessage();
                }
                else
                {
                    if (TlsUtilities.IsTlsV12(state.serverContext))
                    {
                        /*
                         * RFC 5246 If no suitable certificate is available, the client MUST send a
                         * certificate message containing no certificates.
                         * 
                         * NOTE: In previous RFCs, this was SHOULD instead of MUST.
                         */
                        throw new TlsFatalAlert(AlertDescription.unexpected_message);
                    }

                    NotifyClientCertificate(state, Certificate.EmptyChain);
                }
            }

            if (clientMessage.Type == HandshakeType.client_key_exchange)
            {
                ProcessClientKeyExchange(state, clientMessage.Body);
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            TlsHandshakeHash prepareFinishHash = handshake.PrepareToFinish();
            securityParameters.sessionHash = TlsProtocol.GetCurrentPrfHash(state.serverContext, prepareFinishHash, null);

            TlsProtocol.EstablishMasterSecret(state.serverContext, state.keyExchange);
            recordLayer.InitPendingEpoch(state.server.GetCipher());

            /*
             * RFC 5246 7.4.8 This message is only sent following a client certificate that has signing
             * capability (i.e., all certificates except those containing fixed Diffie-Hellman
             * parameters).
             */
            if (ExpectCertificateVerifyMessage(state))
            {
                byte[] certificateVerifyBody = handshake.ReceiveMessageBody(HandshakeType.certificate_verify);
                ProcessCertificateVerify(state, certificateVerifyBody, prepareFinishHash);
            }

            // NOTE: Calculated exclusive of the actual Finished message from the client
            byte[] expectedClientVerifyData = TlsUtilities.CalculateVerifyData(state.serverContext, ExporterLabel.client_finished,
                TlsProtocol.GetCurrentPrfHash(state.serverContext, handshake.HandshakeHash, null));
            ProcessFinished(handshake.ReceiveMessageBody(HandshakeType.finished), expectedClientVerifyData);

            if (state.expectSessionTicket)
            {
                NewSessionTicket newSessionTicket = state.server.GetNewSessionTicket();
                byte[] newSessionTicketBody = GenerateNewSessionTicket(state, newSessionTicket);
                handshake.SendMessage(HandshakeType.session_ticket, newSessionTicketBody);
            }

            // NOTE: Calculated exclusive of the Finished message itself
            byte[] serverVerifyData = TlsUtilities.CalculateVerifyData(state.serverContext, ExporterLabel.server_finished,
                TlsProtocol.GetCurrentPrfHash(state.serverContext, handshake.HandshakeHash, null));
            handshake.SendMessage(HandshakeType.finished, serverVerifyData);

            handshake.Finish();

            state.server.NotifyHandshakeComplete();

            return new DtlsTransport(recordLayer);
        }
Пример #5
0
        internal virtual DtlsTransport ClientHandshake(ClientHandshakeState state, DtlsRecordLayer recordLayer)
        {
            SecurityParameters    securityParameters    = state.clientContext.SecurityParameters;
            DtlsReliableHandshake dtlsReliableHandshake = new DtlsReliableHandshake(state.clientContext, recordLayer);

            byte[] array = GenerateClientHello(state, state.client);
            recordLayer.SetWriteVersion(ProtocolVersion.DTLSv10);
            dtlsReliableHandshake.SendMessage(1, array);
            DtlsReliableHandshake.Message message = dtlsReliableHandshake.ReceiveMessage();
            while (message.Type == 3)
            {
                ProtocolVersion readVersion   = recordLayer.ReadVersion;
                ProtocolVersion clientVersion = state.clientContext.ClientVersion;
                if (!readVersion.IsEqualOrEarlierVersionOf(clientVersion))
                {
                    throw new TlsFatalAlert(47);
                }
                recordLayer.ReadVersion = null;
                byte[] cookie = ProcessHelloVerifyRequest(state, message.Body);
                byte[] body   = PatchClientHelloWithCookie(array, cookie);
                dtlsReliableHandshake.ResetHandshakeMessagesDigest();
                dtlsReliableHandshake.SendMessage(1, body);
                message = dtlsReliableHandshake.ReceiveMessage();
            }
            if (message.Type == 2)
            {
                ProtocolVersion readVersion2 = recordLayer.ReadVersion;
                ReportServerVersion(state, readVersion2);
                recordLayer.SetWriteVersion(readVersion2);
                ProcessServerHello(state, message.Body);
                dtlsReliableHandshake.NotifyHelloComplete();
                DtlsProtocol.ApplyMaxFragmentLengthExtension(recordLayer, securityParameters.maxFragmentLength);
                if (state.resumedSession)
                {
                    securityParameters.masterSecret = Arrays.Clone(state.sessionParameters.MasterSecret);
                    recordLayer.InitPendingEpoch(state.client.GetCipher());
                    byte[] expected_verify_data = TlsUtilities.CalculateVerifyData(state.clientContext, "server finished", TlsProtocol.GetCurrentPrfHash(state.clientContext, dtlsReliableHandshake.HandshakeHash, null));
                    ProcessFinished(dtlsReliableHandshake.ReceiveMessageBody(20), expected_verify_data);
                    byte[] body2 = TlsUtilities.CalculateVerifyData(state.clientContext, "client finished", TlsProtocol.GetCurrentPrfHash(state.clientContext, dtlsReliableHandshake.HandshakeHash, null));
                    dtlsReliableHandshake.SendMessage(20, body2);
                    dtlsReliableHandshake.Finish();
                    state.clientContext.SetResumableSession(state.tlsSession);
                    state.client.NotifyHandshakeComplete();
                    return(new DtlsTransport(recordLayer));
                }
                InvalidateSession(state);
                if (state.selectedSessionID.Length > 0)
                {
                    state.tlsSession = new TlsSessionImpl(state.selectedSessionID, null);
                }
                message = dtlsReliableHandshake.ReceiveMessage();
                if (message.Type == 23)
                {
                    ProcessServerSupplementalData(state, message.Body);
                    message = dtlsReliableHandshake.ReceiveMessage();
                }
                else
                {
                    state.client.ProcessServerSupplementalData(null);
                }
                state.keyExchange = state.client.GetKeyExchange();
                state.keyExchange.Init(state.clientContext);
                Certificate certificate = null;
                if (message.Type == 11)
                {
                    certificate = ProcessServerCertificate(state, message.Body);
                    message     = dtlsReliableHandshake.ReceiveMessage();
                }
                else
                {
                    state.keyExchange.SkipServerCredentials();
                }
                if (certificate == null || certificate.IsEmpty)
                {
                    state.allowCertificateStatus = false;
                }
                if (message.Type == 22)
                {
                    ProcessCertificateStatus(state, message.Body);
                    message = dtlsReliableHandshake.ReceiveMessage();
                }
                if (message.Type == 12)
                {
                    ProcessServerKeyExchange(state, message.Body);
                    message = dtlsReliableHandshake.ReceiveMessage();
                }
                else
                {
                    state.keyExchange.SkipServerKeyExchange();
                }
                if (message.Type == 13)
                {
                    ProcessCertificateRequest(state, message.Body);
                    TlsUtilities.TrackHashAlgorithms(dtlsReliableHandshake.HandshakeHash, state.certificateRequest.SupportedSignatureAlgorithms);
                    message = dtlsReliableHandshake.ReceiveMessage();
                }
                if (message.Type == 14)
                {
                    if (message.Body.Length != 0)
                    {
                        throw new TlsFatalAlert(50);
                    }
                    dtlsReliableHandshake.HandshakeHash.SealHashAlgorithms();
                    global::System.Collections.IList clientSupplementalData = state.client.GetClientSupplementalData();
                    if (clientSupplementalData != null)
                    {
                        byte[] body3 = DtlsProtocol.GenerateSupplementalData(clientSupplementalData);
                        dtlsReliableHandshake.SendMessage(23, body3);
                    }
                    if (state.certificateRequest != null)
                    {
                        state.clientCredentials = state.authentication.GetClientCredentials(state.certificateRequest);
                        Certificate certificate2 = null;
                        if (state.clientCredentials != null)
                        {
                            certificate2 = state.clientCredentials.Certificate;
                        }
                        if (certificate2 == null)
                        {
                            certificate2 = Certificate.EmptyChain;
                        }
                        byte[] body4 = DtlsProtocol.GenerateCertificate(certificate2);
                        dtlsReliableHandshake.SendMessage(11, body4);
                    }
                    if (state.clientCredentials != null)
                    {
                        state.keyExchange.ProcessClientCredentials(state.clientCredentials);
                    }
                    else
                    {
                        state.keyExchange.SkipClientCredentials();
                    }
                    byte[] body5 = GenerateClientKeyExchange(state);
                    dtlsReliableHandshake.SendMessage(16, body5);
                    TlsHandshakeHash tlsHandshakeHash = dtlsReliableHandshake.PrepareToFinish();
                    securityParameters.sessionHash = TlsProtocol.GetCurrentPrfHash(state.clientContext, tlsHandshakeHash, null);
                    TlsProtocol.EstablishMasterSecret(state.clientContext, state.keyExchange);
                    recordLayer.InitPendingEpoch(state.client.GetCipher());
                    if (state.clientCredentials != null && state.clientCredentials is TlsSignerCredentials)
                    {
                        TlsSignerCredentials      tlsSignerCredentials      = (TlsSignerCredentials)state.clientCredentials;
                        SignatureAndHashAlgorithm signatureAndHashAlgorithm = TlsUtilities.GetSignatureAndHashAlgorithm(state.clientContext, tlsSignerCredentials);
                        byte[]          hash              = ((signatureAndHashAlgorithm != null) ? tlsHandshakeHash.GetFinalHash(signatureAndHashAlgorithm.Hash) : securityParameters.SessionHash);
                        byte[]          signature         = tlsSignerCredentials.GenerateCertificateSignature(hash);
                        DigitallySigned certificateVerify = new DigitallySigned(signatureAndHashAlgorithm, signature);
                        byte[]          body6             = GenerateCertificateVerify(state, certificateVerify);
                        dtlsReliableHandshake.SendMessage(15, body6);
                    }
                    byte[] body7 = TlsUtilities.CalculateVerifyData(state.clientContext, "client finished", TlsProtocol.GetCurrentPrfHash(state.clientContext, dtlsReliableHandshake.HandshakeHash, null));
                    dtlsReliableHandshake.SendMessage(20, body7);
                    if (state.expectSessionTicket)
                    {
                        message = dtlsReliableHandshake.ReceiveMessage();
                        if (message.Type != 4)
                        {
                            throw new TlsFatalAlert(10);
                        }
                        ProcessNewSessionTicket(state, message.Body);
                    }
                    byte[] expected_verify_data2 = TlsUtilities.CalculateVerifyData(state.clientContext, "server finished", TlsProtocol.GetCurrentPrfHash(state.clientContext, dtlsReliableHandshake.HandshakeHash, null));
                    ProcessFinished(dtlsReliableHandshake.ReceiveMessageBody(20), expected_verify_data2);
                    dtlsReliableHandshake.Finish();
                    if (state.tlsSession != null)
                    {
                        state.sessionParameters = new SessionParameters.Builder().SetCipherSuite(securityParameters.CipherSuite).SetCompressionAlgorithm(securityParameters.CompressionAlgorithm).SetMasterSecret(securityParameters.MasterSecret)
                                                  .SetPeerCertificate(certificate)
                                                  .SetPskIdentity(securityParameters.PskIdentity)
                                                  .SetSrpIdentity(securityParameters.SrpIdentity)
                                                  .SetServerExtensions(state.serverExtensions)
                                                  .Build();
                        state.tlsSession = TlsUtilities.ImportSession(state.tlsSession.SessionID, state.sessionParameters);
                        state.clientContext.SetResumableSession(state.tlsSession);
                    }
                    state.client.NotifyHandshakeComplete();
                    return(new DtlsTransport(recordLayer));
                }
                throw new TlsFatalAlert(10);
            }
            throw new TlsFatalAlert(10);
        }
Пример #6
0
        internal virtual DtlsTransport ClientHandshake(ClientHandshakeState state, DtlsRecordLayer recordLayer)
        {
            SecurityParameters securityParameters = state.clientContext.SecurityParameters;
            DtlsReliableHandshake handshake = new DtlsReliableHandshake(state.clientContext, recordLayer);

            byte[] clientHelloBody = GenerateClientHello(state, state.client);

            recordLayer.SetWriteVersion(ProtocolVersion.DTLSv10);

            handshake.SendMessage(HandshakeType.client_hello, clientHelloBody);

            DtlsReliableHandshake.Message serverMessage = handshake.ReceiveMessage();

            while (serverMessage.Type == HandshakeType.hello_verify_request)
            {
                ProtocolVersion recordLayerVersion = recordLayer.ReadVersion;
                ProtocolVersion client_version = state.clientContext.ClientVersion;

                /*
                 * RFC 6347 4.2.1 DTLS 1.2 server implementations SHOULD use DTLS version 1.0 regardless of
                 * the version of TLS that is expected to be negotiated. DTLS 1.2 and 1.0 clients MUST use
                 * the version solely to indicate packet formatting (which is the same in both DTLS 1.2 and
                 * 1.0) and not as part of version negotiation.
                 */
                if (!recordLayerVersion.IsEqualOrEarlierVersionOf(client_version))
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);

                recordLayer.ReadVersion = null;

                byte[] cookie = ProcessHelloVerifyRequest(state, serverMessage.Body);
                byte[] patched = PatchClientHelloWithCookie(clientHelloBody, cookie);

                handshake.ResetHandshakeMessagesDigest();
                handshake.SendMessage(HandshakeType.client_hello, patched);

                serverMessage = handshake.ReceiveMessage();
            }

            if (serverMessage.Type == HandshakeType.server_hello)
            {
                ProtocolVersion recordLayerVersion = recordLayer.ReadVersion;
                ReportServerVersion(state, recordLayerVersion);
                recordLayer.SetWriteVersion(recordLayerVersion);

                ProcessServerHello(state, serverMessage.Body);
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            handshake.NotifyHelloComplete();

            ApplyMaxFragmentLengthExtension(recordLayer, securityParameters.maxFragmentLength);

            if (state.resumedSession)
            {
                securityParameters.masterSecret = Arrays.Clone(state.sessionParameters.MasterSecret);
                recordLayer.InitPendingEpoch(state.client.GetCipher());

                // NOTE: Calculated exclusive of the actual Finished message from the server
                byte[] resExpectedServerVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.server_finished,
                    TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
                ProcessFinished(handshake.ReceiveMessageBody(HandshakeType.finished), resExpectedServerVerifyData);

                // NOTE: Calculated exclusive of the Finished message itself
                byte[] resClientVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.client_finished,
                    TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
                handshake.SendMessage(HandshakeType.finished, resClientVerifyData);

                handshake.Finish();

                state.clientContext.SetResumableSession(state.tlsSession);

                state.client.NotifyHandshakeComplete();

                return new DtlsTransport(recordLayer);
            }

            InvalidateSession(state);

            if (state.selectedSessionID.Length > 0)
            {
                state.tlsSession = new TlsSessionImpl(state.selectedSessionID, null);
            }

            serverMessage = handshake.ReceiveMessage();

            if (serverMessage.Type == HandshakeType.supplemental_data)
            {
                ProcessServerSupplementalData(state, serverMessage.Body);
                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                state.client.ProcessServerSupplementalData(null);
            }

            state.keyExchange = state.client.GetKeyExchange();
            state.keyExchange.Init(state.clientContext);

            Certificate serverCertificate = null;

            if (serverMessage.Type == HandshakeType.certificate)
            {
                serverCertificate = ProcessServerCertificate(state, serverMessage.Body);
                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, Certificate is optional
                state.keyExchange.SkipServerCredentials();
            }

            // TODO[RFC 3546] Check whether empty certificates is possible, allowed, or excludes CertificateStatus
            if (serverCertificate == null || serverCertificate.IsEmpty)
            {
                state.allowCertificateStatus = false;
            }

            if (serverMessage.Type == HandshakeType.certificate_status)
            {
                ProcessCertificateStatus(state, serverMessage.Body);
                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, CertificateStatus is optional
            }

            if (serverMessage.Type == HandshakeType.server_key_exchange)
            {
                ProcessServerKeyExchange(state, serverMessage.Body);
                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, ServerKeyExchange is optional
                state.keyExchange.SkipServerKeyExchange();
            }

            if (serverMessage.Type == HandshakeType.certificate_request)
            {
                ProcessCertificateRequest(state, serverMessage.Body);

                /*
                 * TODO Give the client a chance to immediately select the CertificateVerify hash
                 * algorithm here to avoid tracking the other hash algorithms unnecessarily?
                 */
                TlsUtilities.TrackHashAlgorithms(handshake.HandshakeHash,
                    state.certificateRequest.SupportedSignatureAlgorithms);

                serverMessage = handshake.ReceiveMessage();
            }
            else
            {
                // Okay, CertificateRequest is optional
            }

            if (serverMessage.Type == HandshakeType.server_hello_done)
            {
                if (serverMessage.Body.Length != 0)
                {
                    throw new TlsFatalAlert(AlertDescription.decode_error);
                }
            }
            else
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            handshake.HandshakeHash.SealHashAlgorithms();

            IList clientSupplementalData = state.client.GetClientSupplementalData();
            if (clientSupplementalData != null)
            {
                byte[] supplementalDataBody = GenerateSupplementalData(clientSupplementalData);
                handshake.SendMessage(HandshakeType.supplemental_data, supplementalDataBody);
            }

            if (state.certificateRequest != null)
            {
                state.clientCredentials = state.authentication.GetClientCredentials(state.certificateRequest);

                /*
                 * RFC 5246 If no suitable certificate is available, the client MUST send a certificate
                 * message containing no certificates.
                 * 
                 * NOTE: In previous RFCs, this was SHOULD instead of MUST.
                 */
                Certificate clientCertificate = null;
                if (state.clientCredentials != null)
                {
                    clientCertificate = state.clientCredentials.Certificate;
                }
                if (clientCertificate == null)
                {
                    clientCertificate = Certificate.EmptyChain;
                }

                byte[] certificateBody = GenerateCertificate(clientCertificate);
                handshake.SendMessage(HandshakeType.certificate, certificateBody);
            }

            if (state.clientCredentials != null)
            {
                state.keyExchange.ProcessClientCredentials(state.clientCredentials);
            }
            else
            {
                state.keyExchange.SkipClientCredentials();
            }

            byte[] clientKeyExchangeBody = GenerateClientKeyExchange(state);
            handshake.SendMessage(HandshakeType.client_key_exchange, clientKeyExchangeBody);

            TlsHandshakeHash prepareFinishHash = handshake.PrepareToFinish();
            securityParameters.sessionHash = TlsProtocol.GetCurrentPrfHash(state.clientContext, prepareFinishHash, null);

            TlsProtocol.EstablishMasterSecret(state.clientContext, state.keyExchange);
            recordLayer.InitPendingEpoch(state.client.GetCipher());

            if (state.clientCredentials != null && state.clientCredentials is TlsSignerCredentials)
            {
                TlsSignerCredentials signerCredentials = (TlsSignerCredentials)state.clientCredentials;

                /*
                 * RFC 5246 4.7. digitally-signed element needs SignatureAndHashAlgorithm from TLS 1.2
                 */
                SignatureAndHashAlgorithm signatureAndHashAlgorithm = TlsUtilities.GetSignatureAndHashAlgorithm(
                    state.clientContext, signerCredentials);

                byte[] hash;
                if (signatureAndHashAlgorithm == null)
                {
                    hash = securityParameters.SessionHash;
                }
                else
                {
                    hash = prepareFinishHash.GetFinalHash(signatureAndHashAlgorithm.Hash);
                }

                byte[] signature = signerCredentials.GenerateCertificateSignature(hash);
                DigitallySigned certificateVerify = new DigitallySigned(signatureAndHashAlgorithm, signature);
                byte[] certificateVerifyBody = GenerateCertificateVerify(state, certificateVerify);
                handshake.SendMessage(HandshakeType.certificate_verify, certificateVerifyBody);
            }

            // NOTE: Calculated exclusive of the Finished message itself
            byte[] clientVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.client_finished,
                TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
            handshake.SendMessage(HandshakeType.finished, clientVerifyData);

            if (state.expectSessionTicket)
            {
                serverMessage = handshake.ReceiveMessage();
                if (serverMessage.Type == HandshakeType.session_ticket)
                {
                    ProcessNewSessionTicket(state, serverMessage.Body);
                }
                else
                {
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }
            }

            // NOTE: Calculated exclusive of the actual Finished message from the server
            byte[] expectedServerVerifyData = TlsUtilities.CalculateVerifyData(state.clientContext, ExporterLabel.server_finished,
                TlsProtocol.GetCurrentPrfHash(state.clientContext, handshake.HandshakeHash, null));
            ProcessFinished(handshake.ReceiveMessageBody(HandshakeType.finished), expectedServerVerifyData);

            handshake.Finish();

            if (state.tlsSession != null)
            {
                state.sessionParameters = new SessionParameters.Builder()
                    .SetCipherSuite(securityParameters.CipherSuite)
                    .SetCompressionAlgorithm(securityParameters.CompressionAlgorithm)
                    .SetMasterSecret(securityParameters.MasterSecret)
                    .SetPeerCertificate(serverCertificate)
                    .SetPskIdentity(securityParameters.PskIdentity)
                    .SetSrpIdentity(securityParameters.SrpIdentity)
                    // TODO Consider filtering extensions that aren't relevant to resumed sessions
                    .SetServerExtensions(state.serverExtensions)
                    .Build();

                state.tlsSession = TlsUtilities.ImportSession(state.tlsSession.SessionID, state.sessionParameters);

                state.clientContext.SetResumableSession(state.tlsSession);
            }

            state.client.NotifyHandshakeComplete();

            return new DtlsTransport(recordLayer);
        }