예제 #1
0
        protected virtual void SendServerHelloMessage()
        {
            HandshakeMessage message = new HandshakeMessage(HandshakeType.server_hello);

            {
                ProtocolVersion server_version = mTlsServer.GetServerVersion();
                if (!server_version.IsEqualOrEarlierVersionOf(Context.ClientVersion))
                {
                    throw new TlsFatalAlert(AlertDescription.internal_error);
                }

                mRecordStream.ReadVersion = server_version;
                mRecordStream.SetWriteVersion(server_version);
                mRecordStream.SetRestrictReadVersion(true);
                ContextAdmin.SetServerVersion(server_version);

                TlsUtilities.WriteVersion(server_version, message);
            }

            message.Write(this.mSecurityParameters.serverRandom);

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

            int selectedCipherSuite = mTlsServer.GetSelectedCipherSuite();

            if (!Arrays.Contains(mOfferedCipherSuites, selectedCipherSuite) ||
                selectedCipherSuite == CipherSuite.TLS_NULL_WITH_NULL_NULL ||
                CipherSuite.IsScsv(selectedCipherSuite) ||
                !TlsUtilities.IsValidCipherSuiteForVersion(selectedCipherSuite, Context.ServerVersion))
            {
                throw new TlsFatalAlert(AlertDescription.internal_error);
            }
            mSecurityParameters.cipherSuite = selectedCipherSuite;

            byte selectedCompressionMethod = mTlsServer.GetSelectedCompressionMethod();

            if (!Arrays.Contains(mOfferedCompressionMethods, selectedCompressionMethod))
            {
                throw new TlsFatalAlert(AlertDescription.internal_error);
            }
            mSecurityParameters.compressionAlgorithm = selectedCompressionMethod;

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

            this.mServerExtensions = TlsExtensionsUtilities.EnsureExtensionsInitialised(mTlsServer.GetServerExtensions());

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

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

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

            if (TlsUtilities.IsSsl(mTlsServerContext))
            {
                mSecurityParameters.extendedMasterSecret = false;
            }
            else if (mSecurityParameters.IsExtendedMasterSecret)
            {
                TlsExtensionsUtilities.AddExtendedMasterSecretExtension(mServerExtensions);
            }

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

            if (this.mServerExtensions.Count > 0)
            {
                this.mSecurityParameters.encryptThenMac = TlsExtensionsUtilities.HasEncryptThenMacExtension(mServerExtensions);

                this.mSecurityParameters.maxFragmentLength = ProcessMaxFragmentLengthExtension(mClientExtensions,
                                                                                               mServerExtensions, AlertDescription.internal_error);

                this.mSecurityParameters.truncatedHMac = TlsExtensionsUtilities.HasTruncatedHMacExtension(mServerExtensions);

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

                this.mExpectSessionTicket = !mResumedSession &&
                                            TlsUtilities.HasExpectedEmptyExtensionData(mServerExtensions, ExtensionType.session_ticket,
                                                                                       AlertDescription.internal_error);

                WriteExtensions(message, this.mServerExtensions);
            }

            mSecurityParameters.prfAlgorithm = GetPrfAlgorithm(Context, mSecurityParameters.CipherSuite);

            /*
             * RFC 5246 7.4.9. Any cipher suite which does not explicitly specify verify_data_length has
             * a verify_data_length equal to 12. This includes all existing cipher suites.
             */
            mSecurityParameters.verifyDataLength = 12;

            ApplyMaxFragmentLengthExtension();

            message.WriteToRecordStream(this);
        }
예제 #2
0
        protected virtual void ReceiveServerHelloMessage(MemoryStream buf)
        {
            {
                ProtocolVersion server_version = TlsUtilities.ReadVersion(buf);
                if (server_version.IsDtls)
                {
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                }

                // Check that this matches what the server is Sending in the record layer
                if (!server_version.Equals(this.mRecordStream.ReadVersion))
                {
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                }

                ProtocolVersion client_version = Context.ClientVersion;
                if (!server_version.IsEqualOrEarlierVersionOf(client_version))
                {
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                }

                this.mRecordStream.SetWriteVersion(server_version);
                ContextAdmin.SetServerVersion(server_version);
                this.mTlsClient.NotifyServerVersion(server_version);
            }

            /*
             * Read the server random
             */
            this.mSecurityParameters.serverRandom = TlsUtilities.ReadFully(32, buf);

            this.mSelectedSessionID = TlsUtilities.ReadOpaque8(buf);
            if (this.mSelectedSessionID.Length > 32)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }
            this.mTlsClient.NotifySessionID(this.mSelectedSessionID);
            this.mResumedSession = this.mSelectedSessionID.Length > 0 && this.mTlsSession != null &&
                                   Arrays.AreEqual(this.mSelectedSessionID, this.mTlsSession.SessionID);

            /*
             * Find out which CipherSuite the server has chosen and check that it was one of the offered
             * ones, and is a valid selection for the negotiated version.
             */
            int selectedCipherSuite = TlsUtilities.ReadUint16(buf);

            if (!Arrays.Contains(this.mOfferedCipherSuites, selectedCipherSuite) ||
                selectedCipherSuite == CipherSuite.TLS_NULL_WITH_NULL_NULL ||
                CipherSuite.IsScsv(selectedCipherSuite) ||
                !TlsUtilities.IsValidCipherSuiteForVersion(selectedCipherSuite, Context.ServerVersion))
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }
            this.mTlsClient.NotifySelectedCipherSuite(selectedCipherSuite);

            /*
             * Find out which CompressionMethod the server has chosen and check that it was one of the
             * offered ones.
             */
            byte selectedCompressionMethod = TlsUtilities.ReadUint8(buf);

            if (!Arrays.Contains(this.mOfferedCompressionMethods, selectedCompressionMethod))
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }
            this.mTlsClient.NotifySelectedCompressionMethod(selectedCompressionMethod);

            /*
             * RFC 3546 2.2 The extended server hello message format MAY be sent in place of the server
             * hello message when the client has requested extended functionality via the extended
             * client hello message specified in Section 2.1. ... Note that the extended server hello
             * message is only sent in response to an extended client hello message. This prevents the
             * possibility that the extended server hello message could "break" existing TLS 1.0
             * clients.
             */
            this.mServerExtensions = ReadExtensions(buf);

            /*
             * RFC 7627 4. Clients and servers SHOULD NOT accept handshakes that do not use the extended
             * master secret [..]. (and see 5.2, 5.3)
             */
            this.mSecurityParameters.extendedMasterSecret = !TlsUtilities.IsSsl(mTlsClientContext) &&
                                                            TlsExtensionsUtilities.HasExtendedMasterSecretExtension(mServerExtensions);

            if (!mSecurityParameters.IsExtendedMasterSecret &&
                (mResumedSession || mTlsClient.RequiresExtendedMasterSecret()))
            {
                throw new TlsFatalAlert(AlertDescription.handshake_failure);
            }

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

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

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

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

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

            // TODO[compat-gnutls] GnuTLS test server fails to Send renegotiation_info extension when resuming
            this.mTlsClient.NotifySecureRenegotiation(this.mSecureRenegotiation);

            IDictionary sessionClientExtensions = mClientExtensions, sessionServerExtensions = mServerExtensions;

            if (this.mResumedSession)
            {
                if (selectedCipherSuite != this.mSessionParameters.CipherSuite ||
                    selectedCompressionMethod != this.mSessionParameters.CompressionAlgorithm)
                {
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                }

                sessionClientExtensions = null;
                sessionServerExtensions = this.mSessionParameters.ReadServerExtensions();
            }

            this.mSecurityParameters.cipherSuite          = selectedCipherSuite;
            this.mSecurityParameters.compressionAlgorithm = selectedCompressionMethod;

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

                    this.mSecurityParameters.encryptThenMac = serverSentEncryptThenMAC;
                }

                this.mSecurityParameters.maxFragmentLength = ProcessMaxFragmentLengthExtension(sessionClientExtensions,
                                                                                               sessionServerExtensions, AlertDescription.illegal_parameter);

                this.mSecurityParameters.truncatedHMac = TlsExtensionsUtilities.HasTruncatedHMacExtension(sessionServerExtensions);

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

                this.mExpectSessionTicket = !this.mResumedSession &&
                                            TlsUtilities.HasExpectedEmptyExtensionData(sessionServerExtensions, ExtensionType.session_ticket,
                                                                                       AlertDescription.illegal_parameter);
            }

            if (sessionClientExtensions != null)
            {
                this.mTlsClient.ProcessServerExtensions(sessionServerExtensions);
            }

            this.mSecurityParameters.prfAlgorithm = GetPrfAlgorithm(Context, this.mSecurityParameters.CipherSuite);

            /*
             * RFC 5246 7.4.9. Any cipher suite which does not explicitly specify
             * verify_data_length has a verify_data_length equal to 12. This includes all
             * existing cipher suites.
             */
            this.mSecurityParameters.verifyDataLength = 12;
        }
예제 #3
0
        protected virtual byte[] GenerateServerHello(ServerHandshakeState state)
        {
            SecurityParameters securityParameters = state.serverContext.SecurityParameters;

            MemoryStream buf = new MemoryStream();

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

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

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

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

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

            int selectedCipherSuite = state.server.GetSelectedCipherSuite();

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

            byte selectedCompressionMethod = state.server.GetSelectedCompressionMethod();

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

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

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

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

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

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

            if (securityParameters.IsExtendedMasterSecret)
            {
                TlsExtensionsUtilities.AddExtendedMasterSecretExtension(state.serverExtensions);
            }

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

            if (state.serverExtensions.Count > 0)
            {
                securityParameters.encryptThenMac = TlsExtensionsUtilities.HasEncryptThenMacExtension(state.serverExtensions);

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

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

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

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

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

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

            /*
             * RFC 5246 7.4.9. Any cipher suite which does not explicitly specify verify_data_length
             * has a verify_data_length equal to 12. This includes all existing cipher suites.
             */
            securityParameters.verifyDataLength = 12;

            return(buf.ToArray());
        }