public override void ProcessServerKeyExchange(Stream input)
        {
            SecurityParameters securityParameters = mContext.SecurityParameters;

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

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

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

            DigitallySigned signedParams = ParseSignature(input);

            mSignatureAndHashAlgorithm = signedParams.Algorithm;

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

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

            mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(
                                                                        mClientECPointFormats, curveParams, point));
        }
 public override void ProcessClientKeyExchange(Stream input)
 {
     byte[] array = TlsUtilities.ReadOpaque16(input);
     mPsk = mPskIdentityManager.GetPsk(array);
     if (mPsk == null)
     {
         throw new TlsFatalAlert(115);
     }
     mContext.SecurityParameters.pskIdentity = array;
     if (mKeyExchange == 14)
     {
         BigInteger y = TlsDHUtilities.ReadDHParameter(input);
         mDHAgreePublicKey = TlsDHUtilities.ValidateDHPublicKey(new DHPublicKeyParameters(y, mDHParameters));
     }
     else if (mKeyExchange == 24)
     {
         byte[]             encoding   = TlsUtilities.ReadOpaque8(input);
         ECDomainParameters parameters = mECAgreePrivateKey.Parameters;
         mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(mServerECPointFormats, parameters, encoding));
     }
     else if (mKeyExchange == 15)
     {
         byte[] encryptedPreMasterSecret = (!TlsUtilities.IsSsl(mContext)) ? TlsUtilities.ReadOpaque16(input) : Streams.ReadAll(input);
         mPremasterSecret = mServerCredentials.DecryptPreMasterSecret(encryptedPreMasterSecret);
     }
 }
        protected virtual byte[] ProcessHelloVerifyRequest(ClientHandshakeState state, byte[] body)
        {
            MemoryStream buf = new MemoryStream(body, false);

            ProtocolVersion server_version = TlsUtilities.ReadVersion(buf);

            byte[] cookie = TlsUtilities.ReadOpaque8(buf);

            TlsProtocol.AssertEmpty(buf);

            // TODO Seems this behaviour is not yet in line with OpenSSL for DTLS 1.2
            //        reportServerVersion(state, server_version);
            if (!server_version.IsEqualOrEarlierVersionOf(state.clientContext.ClientVersion))
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }

            /*
             * RFC 6347 This specification increases the cookie size limit to 255 bytes for greater
             * future flexibility. The limit remains 32 for previous versions of DTLS.
             */
            if (!ProtocolVersion.DTLSv12.IsEqualOrEarlierVersionOf(server_version) && cookie.Length > 32)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }

            return(cookie);
        }
Beispiel #4
0
        public static UseSrtpData ReadUseSrtpExtension(byte[] extensionData)
        {
            if (extensionData == null)
            {
                throw new ArgumentNullException("extensionData");
            }

            MemoryStream buf = new MemoryStream(extensionData, true);

            // SRTPProtectionProfiles
            int length = TlsUtilities.ReadUint16(buf);

            if (length < 2 || (length & 1) != 0)
            {
                throw new TlsFatalAlert(AlertDescription.decode_error);
            }
            int[] protectionProfiles = TlsUtilities.ReadUint16Array(length / 2, buf);

            // srtp_mki
            byte[] mki = TlsUtilities.ReadOpaque8(buf);

            TlsProtocol.AssertEmpty(buf);

            return(new UseSrtpData(protectionProfiles, mki));
        }
 public override void ProcessClientKeyExchange(Stream input)
 {
     if (mECAgreePublicKey == null)
     {
         byte[]             encoding   = TlsUtilities.ReadOpaque8(input);
         ECDomainParameters parameters = mECAgreePrivateKey.Parameters;
         mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(mServerECPointFormats, parameters, encoding));
     }
 }
    protected virtual void ReceiveClientHelloMessage(MemoryStream buf)
    {
        ProtocolVersion protocolVersion = TlsUtilities.ReadVersion(buf);

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

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

        if (num2 < 1)
        {
            throw new TlsFatalAlert(47);
        }
        mOfferedCompressionMethods = TlsUtilities.ReadUint8Array(num2, buf);
        mClientExtensions          = TlsProtocol.ReadExtensions(buf);
        mSecurityParameters.extendedMasterSecret = TlsExtensionsUtilities.HasExtendedMasterSecretExtension(mClientExtensions);
        ContextAdmin.SetClientVersion(protocolVersion);
        mTlsServer.NotifyClientVersion(protocolVersion);
        mTlsServer.NotifyFallback(Arrays.Contains(mOfferedCipherSuites, 22016));
        mSecurityParameters.clientRandom = clientRandom;
        mTlsServer.NotifyOfferedCipherSuites(mOfferedCipherSuites);
        mTlsServer.NotifyOfferedCompressionMethods(mOfferedCompressionMethods);
        if (Arrays.Contains(mOfferedCipherSuites, 255))
        {
            mSecureRenegotiation = true;
        }
        byte[] extensionData = TlsUtilities.GetExtensionData(mClientExtensions, 65281);
        if (extensionData != null)
        {
            mSecureRenegotiation = true;
            if (!Arrays.ConstantTimeAreEqual(extensionData, TlsProtocol.CreateRenegotiationInfo(TlsUtilities.EmptyBytes)))
            {
                throw new TlsFatalAlert(40);
            }
        }
        mTlsServer.NotifySecureRenegotiation(mSecureRenegotiation);
        if (mClientExtensions != null)
        {
            mTlsServer.ProcessClientExtensions(mClientExtensions);
        }
    }
 public ECPublicKeyParameters DeserializeECPublicKey(byte[] publicKey)
 {
     using var memoryStream = new MemoryStream(publicKey);
     return(TlsEccUtilities.ValidateECPublicKey(
                TlsEccUtilities.DeserializeECPublicKey(
                    _ecPointFormats, _ecParameters,
                    TlsUtilities.ReadOpaque8(memoryStream)
                    )
                ));
 }
        /**
         * Parse a {@link ServerSRPParams} from an {@link InputStream}.
         *
         * @param input
         *            the {@link InputStream} to parse from.
         * @return a {@link ServerSRPParams} object.
         * @throws IOException
         */
        public static ServerSrpParams Parse(Stream input)
        {
            BigInteger N = TlsSrpUtilities.ReadSrpParameter(input);
            BigInteger g = TlsSrpUtilities.ReadSrpParameter(input);

            byte[]     s = TlsUtilities.ReadOpaque8(input);
            BigInteger B = TlsSrpUtilities.ReadSrpParameter(input);

            return(new ServerSrpParams(N, g, s, B));
        }
    public static byte[] ReadSrpExtension(byte[] extensionData)
    {
        if (extensionData == null)
        {
            throw new ArgumentNullException("extensionData");
        }
        MemoryStream memoryStream = new MemoryStream(extensionData, writable: false);

        byte[] result = TlsUtilities.ReadOpaque8(memoryStream);
        TlsProtocol.AssertEmpty(memoryStream);
        return(result);
    }
Beispiel #10
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        public static byte[] ReadSrpExtension(byte[] extensionData)
        {
            if (extensionData == null)
            {
                throw new ArgumentNullException("extensionData");
            }

            MemoryStream buf = new MemoryStream(extensionData, false);

            byte[] identity = TlsUtilities.ReadOpaque8(buf);

            TlsProtocol.AssertEmpty(buf);

            return(identity);
        }
Beispiel #11
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        public override void ProcessClientKeyExchange(Stream input)
        {
            if (mECAgreePublicKey != null)
            {
                // For ecdsa_fixed_ecdh and rsa_fixed_ecdh, the key arrived in the client certificate
                return;
            }

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

            ECDomainParameters curve_params = this.mECAgreePrivateKey.Parameters;

            this.mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(
                                                                             mServerECPointFormats, curve_params, point));
        }
 public override void ProcessServerKeyExchange(Stream input)
 {
     mPskIdentityHint = TlsUtilities.ReadOpaque16(input);
     if (mKeyExchange == 14)
     {
         ServerDHParams serverDHParams = ServerDHParams.Parse(input);
         mDHAgreePublicKey = TlsDHUtilities.ValidateDHPublicKey(serverDHParams.PublicKey);
         mDHParameters     = mDHAgreePublicKey.Parameters;
     }
     else if (mKeyExchange == 24)
     {
         ECDomainParameters curve_params = TlsEccUtilities.ReadECParameters(mNamedCurves, mClientECPointFormats, input);
         byte[]             encoding     = TlsUtilities.ReadOpaque8(input);
         mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(mClientECPointFormats, curve_params, encoding));
     }
 }
Beispiel #13
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        public override void ProcessServerKeyExchange(Stream input)
        {
            if (!RequiresServerKeyExchange)
            {
                throw new TlsFatalAlert(AlertDescription.unexpected_message);
            }

            // ECDH_anon is handled here, ECDHE_* in a subclass

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

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

            this.mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(
                                                                             mClientECPointFormats, curve_params, point));
        }
        public virtual void ProcessServerExtensions(IDictionary serverExtensions)
        {
            /*
             * TlsProtocol implementation validates that any server extensions received correspond to
             * client extensions sent. By default, we don't send any, and this method is not called.
             */
            if (serverExtensions != null)
            {
                /*
                 * RFC 5246 7.4.1.4.1. Servers MUST NOT send this extension.
                 */
                CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.signature_algorithms);

                CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.supported_groups);

                if (TlsEccUtilities.IsEccCipherSuite(this.mSelectedCipherSuite))
                {
                    this.mServerECPointFormats = TlsEccUtilities.GetSupportedPointFormatsExtension(serverExtensions);
                }
                else
                {
                    CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.ec_point_formats);
                }

                /*
                 * RFC 7685 3. The server MUST NOT echo the extension.
                 */
                CheckForUnexpectedServerExtension(serverExtensions, ExtensionType.padding);

                // https://tools.ietf.org/html/rfc7301
                byte[] extensionData = TlsUtilities.GetExtensionData(serverExtensions, ExtensionType.application_layer_protocol_negotiation);
                if (extensionData != null)
                {
                    using (var exBuf = new MemoryStream(extensionData, false))
                    {
                        byte[] alpnList = TlsUtilities.ReadOpaque16(exBuf);

                        // the "ProtocolNameList" MUST contain exactly one "ProtocolName"
                        using (var alpnBuf = new MemoryStream(alpnList)) {
                            byte[] asciiBytes = TlsUtilities.ReadOpaque8(alpnBuf);
                            this.ServerSupportedProtocol = Strings.FromAsciiByteArray(asciiBytes);
                        }
                    }
                }
            }
        }
    public override void ProcessServerKeyExchange(Stream input)
    {
        SecurityParameters securityParameters = mContext.SecurityParameters;
        SignerInputBuffer  signerInputBuffer  = new SignerInputBuffer();
        Stream             input2             = new TeeInputStream(input, signerInputBuffer);
        ECDomainParameters curve_params       = TlsEccUtilities.ReadECParameters(mNamedCurves, mClientECPointFormats, input2);

        byte[]          encoding        = TlsUtilities.ReadOpaque8(input2);
        DigitallySigned digitallySigned = ParseSignature(input);
        ISigner         signer          = InitVerifyer(mTlsSigner, digitallySigned.Algorithm, securityParameters);

        signerInputBuffer.UpdateSigner(signer);
        if (!signer.VerifySignature(digitallySigned.Signature))
        {
            throw new TlsFatalAlert(51);
        }
        mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(mClientECPointFormats, curve_params, encoding));
    }
        public override void ProcessServerKeyExchange(Stream input)
        {
            this.mPskIdentityHint = TlsUtilities.ReadOpaque16(input);

            if (this.mKeyExchange == KeyExchangeAlgorithm.DHE_PSK)
            {
                this.mDHParameters     = TlsDHUtilities.ReceiveDHParameters(mDHVerifier, input);
                this.mDHAgreePublicKey = new DHPublicKeyParameters(TlsDHUtilities.ReadDHParameter(input), mDHParameters);
            }
            else if (this.mKeyExchange == KeyExchangeAlgorithm.ECDHE_PSK)
            {
                ECDomainParameters ecParams = TlsEccUtilities.ReadECParameters(mNamedCurves, mClientECPointFormats, input);

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

                this.mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(
                                                                                 mClientECPointFormats, ecParams, point));
            }
        }
Beispiel #17
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        public override void ProcessClientKeyExchange(Stream input)
        {
            byte[] psk_identity = TlsUtilities.ReadOpaque16(input);

            this.mPsk = mPskIdentityManager.GetPsk(psk_identity);
            if (mPsk == null)
            {
                throw new TlsFatalAlert(AlertDescription.unknown_psk_identity);
            }

            mContext.SecurityParameters.pskIdentity = psk_identity;

            if (this.mKeyExchange == KeyExchangeAlgorithm.DHE_PSK)
            {
                BigInteger Yc = TlsDHUtilities.ReadDHParameter(input);

                this.mDHAgreePublicKey = TlsDHUtilities.ValidateDHPublicKey(new DHPublicKeyParameters(Yc, mDHParameters));
            }
            else if (this.mKeyExchange == KeyExchangeAlgorithm.ECDHE_PSK)
            {
                byte[] point = TlsUtilities.ReadOpaque8(input);

                ECDomainParameters curve_params = this.mECAgreePrivateKey.Parameters;

                this.mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(
                                                                                 mServerECPointFormats, curve_params, point));
            }
            else if (this.mKeyExchange == KeyExchangeAlgorithm.RSA_PSK)
            {
                byte[] encryptedPreMasterSecret;
                if (TlsUtilities.IsSsl(mContext))
                {
                    // TODO Do any SSLv3 clients actually include the length?
                    encryptedPreMasterSecret = Streams.ReadAll(input);
                }
                else
                {
                    encryptedPreMasterSecret = TlsUtilities.ReadOpaque16(input);
                }

                this.mPremasterSecret = mServerCredentials.DecryptPreMasterSecret(encryptedPreMasterSecret);
            }
        }
        protected virtual void ProcessServerHello(ClientHandshakeState state, byte[] body)
        {
            SecurityParameters securityParameters = state.clientContext.SecurityParameters;

            MemoryStream buf = new MemoryStream(body, false);

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

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

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

            int selectedCipherSuite = TlsUtilities.ReadUint16(buf);

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

            byte selectedCompressionMethod = TlsUtilities.ReadUint8(buf);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

                securityParameters.truncatedHMac = TlsExtensionsUtilities.HasTruncatedHMacExtension(sessionServerExtensions);

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

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

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

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

            /*
             * RFC 5246 7.4.9. Any cipher suite which does not explicitly specify verify_data_length has
             * a verify_data_length equal to 12. This includes all existing cipher suites.
             */
            securityParameters.verifyDataLength = 12;
        }
 public static BigInteger ReadECParameter(Stream input)
 {
     return(new BigInteger(1, TlsUtilities.ReadOpaque8(input)));
 }
Beispiel #20
0
        public static ECDomainParameters ReadECParameters(int[] namedCurves, byte[] ecPointFormats, Stream input)
        {
            try
            {
                byte curveType = TlsUtilities.ReadUint8(input);

                switch (curveType)
                {
                case ECCurveType.explicit_prime:
                {
                    CheckNamedCurve(namedCurves, NamedCurve.arbitrary_explicit_prime_curves);

                    BigInteger prime_p      = ReadECParameter(input);
                    BigInteger a            = ReadECFieldElement(prime_p.BitLength, input);
                    BigInteger b            = ReadECFieldElement(prime_p.BitLength, input);
                    byte[]     baseEncoding = TlsUtilities.ReadOpaque8(input);
                    BigInteger order        = ReadECParameter(input);
                    BigInteger cofactor     = ReadECParameter(input);
                    ECCurve    curve        = new FpCurve(prime_p, a, b, order, cofactor);
                    ECPoint    basePoint    = DeserializeECPoint(ecPointFormats, curve, baseEncoding);
                    return(new ECDomainParameters(curve, basePoint, order, cofactor));
                }

                case ECCurveType.explicit_char2:
                {
                    CheckNamedCurve(namedCurves, NamedCurve.arbitrary_explicit_char2_curves);

                    int  m     = TlsUtilities.ReadUint16(input);
                    byte basis = TlsUtilities.ReadUint8(input);
                    if (!ECBasisType.IsValid(basis))
                    {
                        throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                    }

                    int k1 = ReadECExponent(m, input), k2 = -1, k3 = -1;
                    if (basis == ECBasisType.ec_basis_pentanomial)
                    {
                        k2 = ReadECExponent(m, input);
                        k3 = ReadECExponent(m, input);
                    }

                    BigInteger a            = ReadECFieldElement(m, input);
                    BigInteger b            = ReadECFieldElement(m, input);
                    byte[]     baseEncoding = TlsUtilities.ReadOpaque8(input);
                    BigInteger order        = ReadECParameter(input);
                    BigInteger cofactor     = ReadECParameter(input);

                    ECCurve curve = (basis == ECBasisType.ec_basis_pentanomial)
                        ? new F2mCurve(m, k1, k2, k3, a, b, order, cofactor)
                        : new F2mCurve(m, k1, a, b, order, cofactor);

                    ECPoint basePoint = DeserializeECPoint(ecPointFormats, curve, baseEncoding);

                    return(new ECDomainParameters(curve, basePoint, order, cofactor));
                }

                case ECCurveType.named_curve:
                {
                    int namedCurve = TlsUtilities.ReadUint16(input);
                    if (!NamedCurve.RefersToASpecificNamedCurve(namedCurve))
                    {
                        /*
                         * RFC 4492 5.4. All those values of NamedCurve are allowed that refer to a
                         * specific curve. Values of NamedCurve that indicate support for a class of
                         * explicitly defined curves are not allowed here [...].
                         */
                        throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                    }

                    CheckNamedCurve(namedCurves, namedCurve);

                    return(GetParametersForNamedCurve(namedCurve));
                }

                default:
                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
                }
            }
            catch (Exception e)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter, e);
            }
        }
Beispiel #21
0
 public static BigInteger ReadECParameter(Stream input)
 {
     // TODO Are leading zeroes okay here?
     return(new BigInteger(1, TlsUtilities.ReadOpaque8(input)));
 }
Beispiel #22
0
 public static BigInteger ReadECFieldElement(int fieldSize, Stream input)
 {
     return(DeserializeECFieldElement(fieldSize, TlsUtilities.ReadOpaque8(input)));
 }
        protected virtual void ProcessClientHello(ServerHandshakeState state, byte[] body)
        {
            MemoryStream buf = new MemoryStream(body, false);

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

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

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

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

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

            int cipher_suites_length = TlsUtilities.ReadUint16(buf);

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

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

            int compression_methods_length = TlsUtilities.ReadUint8(buf);

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

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

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

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

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

            context.SetClientVersion(client_version);

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

            securityParameters.clientRandom = client_random;

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

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

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

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

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

            state.server.NotifySecureRenegotiation(state.secure_renegotiation);

            if (state.clientExtensions != null)
            {
                state.server.ProcessClientExtensions(state.clientExtensions);
            }
        }
    public static ECDomainParameters ReadECParameters(int[] namedCurves, byte[] ecPointFormats, Stream input)
    {
        try
        {
            switch (TlsUtilities.ReadUint8(input))
            {
            case 1:
            {
                CheckNamedCurve(namedCurves, 65281);
                BigInteger bigInteger3 = ReadECParameter(input);
                BigInteger a2          = ReadECFieldElement(bigInteger3.BitLength, input);
                BigInteger b3          = ReadECFieldElement(bigInteger3.BitLength, input);
                byte[]     encoding2   = TlsUtilities.ReadOpaque8(input);
                BigInteger bigInteger4 = ReadECParameter(input);
                BigInteger bigInteger5 = ReadECParameter(input);
                ECCurve    curve2      = new FpCurve(bigInteger3, a2, b3, bigInteger4, bigInteger5);
                ECPoint    g2          = DeserializeECPoint(ecPointFormats, curve2, encoding2);
                return(new ECDomainParameters(curve2, g2, bigInteger4, bigInteger5));
            }

            case 2:
            {
                CheckNamedCurve(namedCurves, 65282);
                int  num = TlsUtilities.ReadUint16(input);
                byte b   = TlsUtilities.ReadUint8(input);
                if (!ECBasisType.IsValid(b))
                {
                    throw new TlsFatalAlert(47);
                }
                int num2 = ReadECExponent(num, input);
                int k    = -1;
                int k2   = -1;
                if (b == 2)
                {
                    k  = ReadECExponent(num, input);
                    k2 = ReadECExponent(num, input);
                }
                BigInteger a           = ReadECFieldElement(num, input);
                BigInteger b2          = ReadECFieldElement(num, input);
                byte[]     encoding    = TlsUtilities.ReadOpaque8(input);
                BigInteger bigInteger  = ReadECParameter(input);
                BigInteger bigInteger2 = ReadECParameter(input);
                ECCurve    curve       = (b == 2) ? new F2mCurve(num, num2, k, k2, a, b2, bigInteger, bigInteger2) : new F2mCurve(num, num2, a, b2, bigInteger, bigInteger2);
                ECPoint    g           = DeserializeECPoint(ecPointFormats, curve, encoding);
                return(new ECDomainParameters(curve, g, bigInteger, bigInteger2));
            }

            case 3:
            {
                int namedCurve = TlsUtilities.ReadUint16(input);
                if (!NamedCurve.RefersToASpecificNamedCurve(namedCurve))
                {
                    throw new TlsFatalAlert(47);
                }
                CheckNamedCurve(namedCurves, namedCurve);
                return(GetParametersForNamedCurve(namedCurve));
            }

            default:
                throw new TlsFatalAlert(47);
            }
        }
        catch (Exception alertCause)
        {
            throw new TlsFatalAlert(47, alertCause);
        }
    }
        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);

                if (HTTPManager.Logger.Level <= Loglevels.All)
                {
                    HTTPManager.Logger.Verbose("TlsClientProtocol", "ReceiveServerHelloMessage server_version: " + server_version.ToString(), this.LoggingContext);
                }
            }

            /*
             * 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);
            }

            if (HTTPManager.Logger.Level <= Loglevels.All)
            {
                HTTPManager.Logger.Verbose("TlsClientProtocol", "ReceiveServerHelloMessage selectedCipherSuite: " + selectedCipherSuite.ToString("X"), this.LoggingContext);
            }

            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);
            }

            if (HTTPManager.Logger.Level <= Loglevels.All)
            {
                HTTPManager.Logger.Verbose("TlsClientProtocol", "ReceiveServerHelloMessage selectedCompressionMethod: " + selectedCompressionMethod.ToString(), this.LoggingContext);
            }

            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);
                    }

                    if (HTTPManager.Logger.Level <= Loglevels.All)
                    {
                        HTTPManager.Logger.Verbose("TlsClientProtocol", "ReceiveServerHelloMessage mServerExtensions: " + extType.ToString(), this.LoggingContext);
                    }
                }
            }

            /*
             * 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;
        }
        protected virtual void ReceiveClientHelloMessage(MemoryStream buf)
        {
            ProtocolVersion client_version = TlsUtilities.ReadVersion(buf);

            mRecordStream.SetWriteVersion(client_version);

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

            byte[] client_random = TlsUtilities.ReadFully(32, buf);

            /*
             * TODO RFC 5077 3.4. If a ticket is presented by the client, the server MUST NOT attempt to
             * use the Session ID in the ClientHello for stateful session resumption.
             */
            byte[] sessionID = TlsUtilities.ReadOpaque8(buf);
            if (sessionID.Length > 32)
            {
                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
            }

            /*
             * TODO RFC 5246 7.4.1.2. If the session_id field is not empty (implying a session
             * resumption request), this vector MUST include at least the cipher_suite from that
             * session.
             */
            int cipher_suites_length = TlsUtilities.ReadUint16(buf);

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

            this.mOfferedCipherSuites = TlsUtilities.ReadUint16Array(cipher_suites_length / 2, buf);

            /*
             * TODO RFC 5246 7.4.1.2. If the session_id field is not empty (implying a session
             * resumption request), it MUST include the compression_method from that session.
             */
            int compression_methods_length = TlsUtilities.ReadUint8(buf);

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

            this.mOfferedCompressionMethods = TlsUtilities.ReadUint8Array(compression_methods_length, buf);

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

            /*
             * TODO[resumption] Check RFC 7627 5.4. for required behaviour
             */

            /*
             * 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 = TlsExtensionsUtilities.HasExtendedMasterSecretExtension(mClientExtensions);
            if (!mSecurityParameters.IsExtendedMasterSecret && mTlsServer.RequiresExtendedMasterSecret())
            {
                throw new TlsFatalAlert(AlertDescription.handshake_failure);
            }

            ContextAdmin.SetClientVersion(client_version);

            mTlsServer.NotifyClientVersion(client_version);
            mTlsServer.NotifyFallback(Arrays.Contains(mOfferedCipherSuites, CipherSuite.TLS_FALLBACK_SCSV));

            mSecurityParameters.clientRandom = client_random;

            mTlsServer.NotifyOfferedCipherSuites(mOfferedCipherSuites);
            mTlsServer.NotifyOfferedCompressionMethods(mOfferedCompressionMethods);

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

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

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

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

            mTlsServer.NotifySecureRenegotiation(this.mSecureRenegotiation);

            if (mClientExtensions != null)
            {
                // NOTE: Validates the padding extension data, if present
                TlsExtensionsUtilities.GetPaddingExtension(mClientExtensions);

                mTlsServer.ProcessClientExtensions(mClientExtensions);
            }
        }