protected virtual void SendCertificateVerifyMessage(DigitallySigned certificateVerify)
        {
            HandshakeMessage message = new HandshakeMessage(HandshakeType.certificate_verify);

            certificateVerify.Encode(message);

            message.WriteToRecordStream(this);
        }
Beispiel #2
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        protected virtual DigitallySigned ParseSignature(Stream input)
        {
            DigitallySigned           signature          = DigitallySigned.Parse(mContext, input);
            SignatureAndHashAlgorithm signatureAlgorithm = signature.Algorithm;

            if (signatureAlgorithm != null)
            {
                TlsUtilities.VerifySupportedSignatureAlgorithm(mSupportedSignatureAlgorithms, signatureAlgorithm);
            }
            return(signature);
        }
Beispiel #3
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        public override void ProcessServerKeyExchange(Stream input)
        {
            SecurityParameters securityParameters = mContext.SecurityParameters;

            SignerInputBuffer buf   = null;
            Stream            teeIn = input;

            if (mTlsSigner != null)
            {
                buf   = new SignerInputBuffer();
                teeIn = new TeeInputStream(input, buf);
            }

            ServerSrpParams srpParams = ServerSrpParams.Parse(teeIn);

            if (buf != null)
            {
                DigitallySigned signed_params = ParseSignature(input);

                ISigner signer = InitVerifyer(mTlsSigner, signed_params.Algorithm, securityParameters);
                buf.UpdateSigner(signer);
                if (!signer.VerifySignature(signed_params.Signature))
                {
                    throw new TlsFatalAlert(AlertDescription.decrypt_error);
                }
            }

            this.mSrpGroup = new Srp6GroupParameters(srpParams.N, srpParams.G);

            if (!mGroupVerifier.Accept(mSrpGroup))
            {
                throw new TlsFatalAlert(AlertDescription.insufficient_security);
            }

            this.mSrpSalt = srpParams.S;

            /*
             * RFC 5054 2.5.3: The client MUST abort the handshake with an "illegal_parameter" alert if
             * B % N = 0.
             */
            try
            {
                this.mSrpPeerCredentials = Srp6Utilities.ValidatePublicValue(mSrpGroup.N, srpParams.B);
            }
            catch (CryptoException e)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter, e);
            }

            this.mSrpClient.Init(mSrpGroup, TlsUtilities.CreateHash(HashAlgorithm.sha1), mContext.SecureRandom);
        }
        protected virtual void ProcessCertificateVerify(ServerHandshakeState state, byte[] body, TlsHandshakeHash prepareFinishHash)
        {
            if (state.certificateRequest == null)
            {
                throw new InvalidOperationException();
            }

            MemoryStream buf = new MemoryStream(body, false);

            TlsServerContextImpl context = state.serverContext;
            DigitallySigned      clientCertificateVerify = DigitallySigned.Parse(context, buf);

            TlsProtocol.AssertEmpty(buf);

            // Verify the CertificateVerify message contains a correct signature.
            try
            {
                SignatureAndHashAlgorithm signatureAlgorithm = clientCertificateVerify.Algorithm;

                byte[] hash;
                if (TlsUtilities.IsTlsV12(context))
                {
                    TlsUtilities.VerifySupportedSignatureAlgorithm(state.certificateRequest.SupportedSignatureAlgorithms, signatureAlgorithm);
                    hash = prepareFinishHash.GetFinalHash(signatureAlgorithm.Hash);
                }
                else
                {
                    hash = context.SecurityParameters.SessionHash;
                }

                X509CertificateStructure x509Cert  = state.clientCertificate.GetCertificateAt(0);
                SubjectPublicKeyInfo     keyInfo   = x509Cert.SubjectPublicKeyInfo;
                AsymmetricKeyParameter   publicKey = PublicKeyFactory.CreateKey(keyInfo);

                TlsSigner tlsSigner = TlsUtilities.CreateTlsSigner((byte)state.clientCertificateType);
                tlsSigner.Init(context);
                if (!tlsSigner.VerifyRawSignature(signatureAlgorithm, clientCertificateVerify.Signature, publicKey, hash))
                {
                    throw new TlsFatalAlert(AlertDescription.decrypt_error);
                }
            }
            catch (TlsFatalAlert e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new TlsFatalAlert(AlertDescription.decrypt_error, e);
            }
        }
        protected virtual void ReceiveCertificateVerifyMessage(MemoryStream buf)
        {
            if (mCertificateRequest == null)
            {
                throw new InvalidOperationException();
            }

            DigitallySigned clientCertificateVerify = DigitallySigned.Parse(Context, buf);

            AssertEmpty(buf);

            // Verify the CertificateVerify message contains a correct signature.
            try
            {
                SignatureAndHashAlgorithm signatureAlgorithm = clientCertificateVerify.Algorithm;

                byte[] hash;
                if (TlsUtilities.IsTlsV12(Context))
                {
                    TlsUtilities.VerifySupportedSignatureAlgorithm(mCertificateRequest.SupportedSignatureAlgorithms, signatureAlgorithm);
                    hash = mPrepareFinishHash.GetFinalHash(signatureAlgorithm.Hash);
                }
                else
                {
                    hash = mSecurityParameters.SessionHash;
                }

                X509CertificateStructure x509Cert  = mPeerCertificate.GetCertificateAt(0);
                SubjectPublicKeyInfo     keyInfo   = x509Cert.SubjectPublicKeyInfo;
                AsymmetricKeyParameter   publicKey = PublicKeyFactory.CreateKey(keyInfo);

                TlsSigner tlsSigner = TlsUtilities.CreateTlsSigner((byte)mClientCertificateType);
                tlsSigner.Init(Context);
                if (!tlsSigner.VerifyRawSignature(signatureAlgorithm, clientCertificateVerify.Signature, publicKey, hash))
                {
                    throw new TlsFatalAlert(AlertDescription.decrypt_error);
                }
            }
            catch (TlsFatalAlert e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new TlsFatalAlert(AlertDescription.decrypt_error, e);
            }
        }
Beispiel #6
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        public override void ProcessServerKeyExchange(Stream input)
        {
            SecurityParameters securityParameters = mContext.SecurityParameters;

            SignerInputBuffer buf   = new SignerInputBuffer();
            Stream            teeIn = new TeeInputStream(input, buf);

            ServerDHParams dhParams = ServerDHParams.Parse(teeIn);

            DigitallySigned signed_params = ParseSignature(input);

            ISigner signer = InitVerifyer(mTlsSigner, signed_params.Algorithm, securityParameters);

            buf.UpdateSigner(signer);
            if (!signer.VerifySignature(signed_params.Signature))
            {
                throw new TlsFatalAlert(AlertDescription.decrypt_error);
            }

            this.mDHAgreePublicKey = TlsDHUtilities.ValidateDHPublicKey(dhParams.PublicKey);
            this.mDHParameters     = ValidateDHParameters(mDHAgreePublicKey.Parameters);
        }
Beispiel #7
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        public override byte[] GenerateServerKeyExchange()
        {
            mSrpServer.Init(mSrpGroup, mSrpVerifier, TlsUtilities.CreateHash(HashAlgorithm.sha1), mContext.SecureRandom);
            BigInteger B = mSrpServer.GenerateServerCredentials();

            ServerSrpParams srpParams = new ServerSrpParams(mSrpGroup.N, mSrpGroup.G, mSrpSalt, B);

            DigestInputBuffer buf = new DigestInputBuffer();

            srpParams.Encode(buf);

            if (mServerCredentials != null)
            {
                /*
                 * RFC 5246 4.7. digitally-signed element needs SignatureAndHashAlgorithm from TLS 1.2
                 */
                SignatureAndHashAlgorithm signatureAndHashAlgorithm = TlsUtilities.GetSignatureAndHashAlgorithm(
                    mContext, mServerCredentials);

                IDigest d = TlsUtilities.CreateHash(signatureAndHashAlgorithm);

                SecurityParameters securityParameters = mContext.SecurityParameters;
                d.BlockUpdate(securityParameters.clientRandom, 0, securityParameters.clientRandom.Length);
                d.BlockUpdate(securityParameters.serverRandom, 0, securityParameters.serverRandom.Length);
                buf.UpdateDigest(d);

                byte[] hash = new byte[d.GetDigestSize()];
                d.DoFinal(hash, 0);

                byte[] signature = mServerCredentials.GenerateCertificateSignature(hash);

                DigitallySigned signed_params = new DigitallySigned(signatureAndHashAlgorithm, signature);
                signed_params.Encode(buf);
            }

            return(buf.ToArray());
        }
        public override void ProcessServerKeyExchange(Stream input)
        {
            SecurityParameters securityParameters = mContext.SecurityParameters;

            SignerInputBuffer buf   = new SignerInputBuffer();
            Stream            teeIn = new TeeInputStream(input, buf);

            ECDomainParameters curve_params = TlsEccUtilities.ReadECParameters(mNamedCurves, mClientECPointFormats, teeIn);

            byte[] point = TlsUtilities.ReadOpaque8(teeIn);

            DigitallySigned signed_params = ParseSignature(input);

            ISigner signer = InitVerifyer(mTlsSigner, signed_params.Algorithm, securityParameters);

            buf.UpdateSigner(signer);
            if (!signer.VerifySignature(signed_params.Signature))
            {
                throw new TlsFatalAlert(AlertDescription.decrypt_error);
            }

            this.mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(
                                                                             mClientECPointFormats, curve_params, point));
        }
Beispiel #9
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        public override byte[] GenerateServerKeyExchange()
        {
            if (this.mDHParameters == null)
            {
                throw new TlsFatalAlert(AlertDescription.internal_error);
            }

            DigestInputBuffer buf = new DigestInputBuffer();

            this.mDHAgreePrivateKey = TlsDHUtilities.GenerateEphemeralServerKeyExchange(mContext.SecureRandom,
                                                                                        this.mDHParameters, buf);

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

            IDigest d = TlsUtilities.CreateHash(signatureAndHashAlgorithm);

            SecurityParameters securityParameters = mContext.SecurityParameters;

            d.BlockUpdate(securityParameters.clientRandom, 0, securityParameters.clientRandom.Length);
            d.BlockUpdate(securityParameters.serverRandom, 0, securityParameters.serverRandom.Length);
            buf.UpdateDigest(d);

            byte[] hash = DigestUtilities.DoFinal(d);

            byte[] signature = mServerCredentials.GenerateCertificateSignature(hash);

            DigitallySigned signed_params = new DigitallySigned(signatureAndHashAlgorithm, signature);

            signed_params.Encode(buf);

            return(buf.ToArray());
        }
        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));
        }
        protected virtual byte[] GenerateCertificateVerify(ClientHandshakeState state, DigitallySigned certificateVerify)
        {
            MemoryStream buf = new MemoryStream();

            certificateVerify.Encode(buf);
            return(buf.ToArray());
        }
        protected override void HandleHandshakeMessage(byte type, byte[] data)
        {
            MemoryStream buf = new MemoryStream(data, false);

            if (this.mResumedSession)
            {
                if (type != HandshakeType.finished || this.mConnectionState != CS_SERVER_HELLO)
                {
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }

                ProcessFinishedMessage(buf);
                this.mConnectionState = CS_SERVER_FINISHED;

                SendFinishedMessage();
                this.mConnectionState = CS_CLIENT_FINISHED;
                this.mConnectionState = CS_END;

                CompleteHandshake();
                return;
            }

            switch (type)
            {
            case HandshakeType.certificate:
            {
                switch (this.mConnectionState)
                {
                case CS_SERVER_HELLO:
                case CS_SERVER_SUPPLEMENTAL_DATA:
                {
                    if (this.mConnectionState == CS_SERVER_HELLO)
                    {
                        HandleSupplementalData(null);
                    }

                    // Parse the Certificate message and Send to cipher suite

                    this.mPeerCertificate = Certificate.Parse(buf);

                    AssertEmpty(buf);

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

                    this.mKeyExchange.ProcessServerCertificate(this.mPeerCertificate);

                    this.mAuthentication = mTlsClient.GetAuthentication();
                    this.mAuthentication.NotifyServerCertificate(this.mPeerCertificate);

                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }

                this.mConnectionState = CS_SERVER_CERTIFICATE;
                break;
            }

            case HandshakeType.certificate_status:
            {
                switch (this.mConnectionState)
                {
                case CS_SERVER_CERTIFICATE:
                {
                    if (!this.mAllowCertificateStatus)
                    {
                        /*
                         * RFC 3546 3.6. If a server returns a "CertificateStatus" message, then the
                         * server MUST have included an extension of type "status_request" with empty
                         * "extension_data" in the extended server hello..
                         */
                        throw new TlsFatalAlert(AlertDescription.unexpected_message);
                    }

                    this.mCertificateStatus = CertificateStatus.Parse(buf);

                    AssertEmpty(buf);

                    // TODO[RFC 3546] Figure out how to provide this to the client/authentication.

                    this.mConnectionState = CS_CERTIFICATE_STATUS;
                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }
                break;
            }

            case HandshakeType.finished:
            {
                switch (this.mConnectionState)
                {
                case CS_CLIENT_FINISHED:
                case CS_SERVER_SESSION_TICKET:
                {
                    if (this.mConnectionState == CS_CLIENT_FINISHED && this.mExpectSessionTicket)
                    {
                        /*
                         * RFC 5077 3.3. This message MUST be sent if the server included a
                         * SessionTicket extension in the ServerHello.
                         */
                        throw new TlsFatalAlert(AlertDescription.unexpected_message);
                    }

                    ProcessFinishedMessage(buf);
                    this.mConnectionState = CS_SERVER_FINISHED;
                    this.mConnectionState = CS_END;

                    CompleteHandshake();
                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }
                break;
            }

            case HandshakeType.server_hello:
            {
                switch (this.mConnectionState)
                {
                case CS_CLIENT_HELLO:
                {
                    ReceiveServerHelloMessage(buf);
                    this.mConnectionState = CS_SERVER_HELLO;

                    this.mRecordStream.NotifyHelloComplete();

                    ApplyMaxFragmentLengthExtension();

                    if (this.mResumedSession)
                    {
                        this.mSecurityParameters.masterSecret = Arrays.Clone(this.mSessionParameters.MasterSecret);
                        this.mRecordStream.SetPendingConnectionState(Peer.GetCompression(), Peer.GetCipher());

                        SendChangeCipherSpecMessage();
                    }
                    else
                    {
                        InvalidateSession();

                        if (this.mSelectedSessionID.Length > 0)
                        {
                            this.mTlsSession = new TlsSessionImpl(this.mSelectedSessionID, null);
                        }
                    }

                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }
                break;
            }

            case HandshakeType.supplemental_data:
            {
                switch (this.mConnectionState)
                {
                case CS_SERVER_HELLO:
                {
                    HandleSupplementalData(ReadSupplementalDataMessage(buf));
                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }
                break;
            }

            case HandshakeType.server_hello_done:
            {
                switch (this.mConnectionState)
                {
                case CS_SERVER_HELLO:
                case CS_SERVER_SUPPLEMENTAL_DATA:
                case CS_SERVER_CERTIFICATE:
                case CS_CERTIFICATE_STATUS:
                case CS_SERVER_KEY_EXCHANGE:
                case CS_CERTIFICATE_REQUEST:
                {
                    if (mConnectionState < CS_SERVER_SUPPLEMENTAL_DATA)
                    {
                        HandleSupplementalData(null);
                    }

                    if (mConnectionState < CS_SERVER_CERTIFICATE)
                    {
                        // There was no server certificate message; check it's OK
                        this.mKeyExchange.SkipServerCredentials();
                        this.mAuthentication = null;
                    }

                    if (mConnectionState < CS_SERVER_KEY_EXCHANGE)
                    {
                        // There was no server key exchange message; check it's OK
                        this.mKeyExchange.SkipServerKeyExchange();
                    }

                    AssertEmpty(buf);

                    this.mConnectionState = CS_SERVER_HELLO_DONE;

                    this.mRecordStream.HandshakeHash.SealHashAlgorithms();

                    IList clientSupplementalData = mTlsClient.GetClientSupplementalData();
                    if (clientSupplementalData != null)
                    {
                        SendSupplementalDataMessage(clientSupplementalData);
                    }
                    this.mConnectionState = CS_CLIENT_SUPPLEMENTAL_DATA;

                    TlsCredentials clientCreds = null;
                    if (mCertificateRequest == null)
                    {
                        this.mKeyExchange.SkipClientCredentials();
                    }
                    else
                    {
                        clientCreds = this.mAuthentication.GetClientCredentials(mCertificateRequest);

                        if (clientCreds == null)
                        {
                            this.mKeyExchange.SkipClientCredentials();

                            /*
                             * 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.
                             */
                            SendCertificateMessage(Certificate.EmptyChain);
                        }
                        else
                        {
                            this.mKeyExchange.ProcessClientCredentials(clientCreds);

                            SendCertificateMessage(clientCreds.Certificate);
                        }
                    }

                    this.mConnectionState = CS_CLIENT_CERTIFICATE;

                    /*
                     * Send the client key exchange message, depending on the key exchange we are using
                     * in our CipherSuite.
                     */
                    SendClientKeyExchangeMessage();
                    this.mConnectionState = CS_CLIENT_KEY_EXCHANGE;

                    TlsHandshakeHash prepareFinishHash = mRecordStream.PrepareToFinish();
                    this.mSecurityParameters.sessionHash = GetCurrentPrfHash(Context, prepareFinishHash, null);

                    EstablishMasterSecret(Context, mKeyExchange);
                    mRecordStream.SetPendingConnectionState(Peer.GetCompression(), Peer.GetCipher());

                    if (clientCreds != null && clientCreds is TlsSignerCredentials)
                    {
                        TlsSignerCredentials signerCredentials = (TlsSignerCredentials)clientCreds;

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

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

                        byte[]          signature         = signerCredentials.GenerateCertificateSignature(hash);
                        DigitallySigned certificateVerify = new DigitallySigned(signatureAndHashAlgorithm, signature);
                        SendCertificateVerifyMessage(certificateVerify);

                        this.mConnectionState = CS_CERTIFICATE_VERIFY;
                    }

                    SendChangeCipherSpecMessage();
                    SendFinishedMessage();
                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.handshake_failure);
                }

                this.mConnectionState = CS_CLIENT_FINISHED;
                break;
            }

            case HandshakeType.server_key_exchange:
            {
                switch (this.mConnectionState)
                {
                case CS_SERVER_HELLO:
                case CS_SERVER_SUPPLEMENTAL_DATA:
                case CS_SERVER_CERTIFICATE:
                case CS_CERTIFICATE_STATUS:
                {
                    if (mConnectionState < CS_SERVER_SUPPLEMENTAL_DATA)
                    {
                        HandleSupplementalData(null);
                    }

                    if (mConnectionState < CS_SERVER_CERTIFICATE)
                    {
                        // There was no server certificate message; check it's OK
                        this.mKeyExchange.SkipServerCredentials();
                        this.mAuthentication = null;
                    }

                    this.mKeyExchange.ProcessServerKeyExchange(buf);

                    AssertEmpty(buf);
                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }

                this.mConnectionState = CS_SERVER_KEY_EXCHANGE;
                break;
            }

            case HandshakeType.certificate_request:
            {
                switch (this.mConnectionState)
                {
                case CS_SERVER_CERTIFICATE:
                case CS_CERTIFICATE_STATUS:
                case CS_SERVER_KEY_EXCHANGE:
                {
                    if (this.mConnectionState != CS_SERVER_KEY_EXCHANGE)
                    {
                        // There was no server key exchange message; check it's OK
                        this.mKeyExchange.SkipServerKeyExchange();
                    }

                    if (this.mAuthentication == null)
                    {
                        /*
                         * RFC 2246 7.4.4. It is a fatal handshake_failure alert for an anonymous server
                         * to request client identification.
                         */
                        throw new TlsFatalAlert(AlertDescription.handshake_failure);
                    }

                    this.mCertificateRequest = CertificateRequest.Parse(Context, buf);

                    AssertEmpty(buf);

                    this.mKeyExchange.ValidateCertificateRequest(this.mCertificateRequest);

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

                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }

                this.mConnectionState = CS_CERTIFICATE_REQUEST;
                break;
            }

            case HandshakeType.session_ticket:
            {
                switch (this.mConnectionState)
                {
                case CS_CLIENT_FINISHED:
                {
                    if (!this.mExpectSessionTicket)
                    {
                        /*
                         * RFC 5077 3.3. This message MUST NOT be sent if the server did not include a
                         * SessionTicket extension in the ServerHello.
                         */
                        throw new TlsFatalAlert(AlertDescription.unexpected_message);
                    }

                    /*
                     * RFC 5077 3.4. If the client receives a session ticket from the server, then it
                     * discards any Session ID that was sent in the ServerHello.
                     */
                    InvalidateSession();

                    ReceiveNewSessionTicketMessage(buf);
                    break;
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.unexpected_message);
                }

                this.mConnectionState = CS_SERVER_SESSION_TICKET;
                break;
            }

            case HandshakeType.hello_request:
            {
                AssertEmpty(buf);

                /*
                 * RFC 2246 7.4.1.1 Hello request This message will be ignored by the client if the
                 * client is currently negotiating a session. This message may be ignored by the client
                 * if it does not wish to renegotiate a session, or the client may, if it wishes,
                 * respond with a no_renegotiation alert.
                 */
                if (this.mConnectionState == CS_END)
                {
                    RefuseRenegotiation();
                }
                break;
            }

            case HandshakeType.client_hello:
            case HandshakeType.client_key_exchange:
            case HandshakeType.certificate_verify:
            case HandshakeType.hello_verify_request:
            default:
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }
        }