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));
}
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 TlsServerContextImpl(SecureRandom secureRandom, SecurityParameters securityParameters)
: base(secureRandom, securityParameters)
{
}
internal TlsClientContextImpl(SecureRandom secureRandom, SecurityParameters securityParameters)
: base(secureRandom, securityParameters)
{
}
internal virtual DtlsTransport ServerHandshake(ServerHandshakeState state, DtlsRecordLayer recordLayer)
{
SecurityParameters securityParameters = state.serverContext.SecurityParameters;
DtlsReliableHandshake handshake = new DtlsReliableHandshake(state.serverContext, recordLayer);
DtlsReliableHandshake.Message clientMessage = handshake.ReceiveMessage();
// NOTE: DTLSRecordLayer requires any DTLS version, we don't otherwise constrain this
//ProtocolVersion recordLayerVersion = recordLayer.ReadVersion;
if (clientMessage.Type == HandshakeType.client_hello)
{
ProcessClientHello(state, clientMessage.Body);
}
else
{
throw new TlsFatalAlert(AlertDescription.unexpected_message);
}
{
byte[] serverHelloBody = GenerateServerHello(state);
ApplyMaxFragmentLengthExtension(recordLayer, securityParameters.maxFragmentLength);
ProtocolVersion recordLayerVersion = state.serverContext.ServerVersion;
recordLayer.ReadVersion = recordLayerVersion;
recordLayer.SetWriteVersion(recordLayerVersion);
handshake.SendMessage(HandshakeType.server_hello, serverHelloBody);
}
handshake.NotifyHelloComplete();
IList serverSupplementalData = state.server.GetServerSupplementalData();
if (serverSupplementalData != null)
{
byte[] supplementalDataBody = GenerateSupplementalData(serverSupplementalData);
handshake.SendMessage(HandshakeType.supplemental_data, supplementalDataBody);
}
state.keyExchange = state.server.GetKeyExchange();
state.keyExchange.Init(state.serverContext);
state.serverCredentials = state.server.GetCredentials();
Certificate serverCertificate = null;
if (state.serverCredentials == null)
{
state.keyExchange.SkipServerCredentials();
}
else
{
state.keyExchange.ProcessServerCredentials(state.serverCredentials);
serverCertificate = state.serverCredentials.Certificate;
byte[] certificateBody = GenerateCertificate(serverCertificate);
handshake.SendMessage(HandshakeType.certificate, certificateBody);
}
// TODO[RFC 3546] Check whether empty certificates is possible, allowed, or excludes CertificateStatus
if (serverCertificate == null || serverCertificate.IsEmpty)
{
state.allowCertificateStatus = false;
}
if (state.allowCertificateStatus)
{
CertificateStatus certificateStatus = state.server.GetCertificateStatus();
if (certificateStatus != null)
{
byte[] certificateStatusBody = GenerateCertificateStatus(state, certificateStatus);
handshake.SendMessage(HandshakeType.certificate_status, certificateStatusBody);
}
}
byte[] serverKeyExchange = state.keyExchange.GenerateServerKeyExchange();
if (serverKeyExchange != null)
{
handshake.SendMessage(HandshakeType.server_key_exchange, serverKeyExchange);
}
if (state.serverCredentials != null)
{
state.certificateRequest = state.server.GetCertificateRequest();
if (state.certificateRequest != null)
{
if (TlsUtilities.IsTlsV12(state.serverContext) != (state.certificateRequest.SupportedSignatureAlgorithms != null))
{
throw new TlsFatalAlert(AlertDescription.internal_error);
}
state.keyExchange.ValidateCertificateRequest(state.certificateRequest);
byte[] certificateRequestBody = GenerateCertificateRequest(state, state.certificateRequest);
handshake.SendMessage(HandshakeType.certificate_request, certificateRequestBody);
TlsUtilities.TrackHashAlgorithms(handshake.HandshakeHash,
state.certificateRequest.SupportedSignatureAlgorithms);
}
}
handshake.SendMessage(HandshakeType.server_hello_done, TlsUtilities.EmptyBytes);
handshake.HandshakeHash.SealHashAlgorithms();
clientMessage = handshake.ReceiveMessage();
if (clientMessage.Type == HandshakeType.supplemental_data)
{
ProcessClientSupplementalData(state, clientMessage.Body);
clientMessage = handshake.ReceiveMessage();
}
else
{
state.server.ProcessClientSupplementalData(null);
}
if (state.certificateRequest == null)
{
state.keyExchange.SkipClientCredentials();
}
else
{
if (clientMessage.Type == HandshakeType.certificate)
{
ProcessClientCertificate(state, clientMessage.Body);
clientMessage = handshake.ReceiveMessage();
}
else
{
if (TlsUtilities.IsTlsV12(state.serverContext))
{
/*
* RFC 5246 If no suitable certificate is available, the client MUST send a
* certificate message containing no certificates.
*
* NOTE: In previous RFCs, this was SHOULD instead of MUST.
*/
throw new TlsFatalAlert(AlertDescription.unexpected_message);
}
NotifyClientCertificate(state, Certificate.EmptyChain);
}
}
if (clientMessage.Type == HandshakeType.client_key_exchange)
{
ProcessClientKeyExchange(state, clientMessage.Body);
}
else
{
throw new TlsFatalAlert(AlertDescription.unexpected_message);
}
TlsHandshakeHash prepareFinishHash = handshake.PrepareToFinish();
securityParameters.sessionHash = TlsProtocol.GetCurrentPrfHash(state.serverContext, prepareFinishHash, null);
TlsProtocol.EstablishMasterSecret(state.serverContext, state.keyExchange);
recordLayer.InitPendingEpoch(state.server.GetCipher());
/*
* RFC 5246 7.4.8 This message is only sent following a client certificate that has signing
* capability (i.e., all certificates except those containing fixed Diffie-Hellman
* parameters).
*/
if (ExpectCertificateVerifyMessage(state))
{
byte[] certificateVerifyBody = handshake.ReceiveMessageBody(HandshakeType.certificate_verify);
ProcessCertificateVerify(state, certificateVerifyBody, prepareFinishHash);
}
// NOTE: Calculated exclusive of the actual Finished message from the client
byte[] expectedClientVerifyData = TlsUtilities.CalculateVerifyData(state.serverContext, ExporterLabel.client_finished,
TlsProtocol.GetCurrentPrfHash(state.serverContext, handshake.HandshakeHash, null));
ProcessFinished(handshake.ReceiveMessageBody(HandshakeType.finished), expectedClientVerifyData);
if (state.expectSessionTicket)
{
NewSessionTicket newSessionTicket = state.server.GetNewSessionTicket();
byte[] newSessionTicketBody = GenerateNewSessionTicket(state, newSessionTicket);
handshake.SendMessage(HandshakeType.session_ticket, newSessionTicketBody);
}
// NOTE: Calculated exclusive of the Finished message itself
byte[] serverVerifyData = TlsUtilities.CalculateVerifyData(state.serverContext, ExporterLabel.server_finished,
TlsProtocol.GetCurrentPrfHash(state.serverContext, handshake.HandshakeHash, null));
handshake.SendMessage(HandshakeType.finished, serverVerifyData);
handshake.Finish();
state.server.NotifyHandshakeComplete();
return(new DtlsTransport(recordLayer));
}
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)
{
// NOTE: Validates the padding extension data, if present
TlsExtensionsUtilities.GetPaddingExtension(state.clientExtensions);
state.server.ProcessClientExtensions(state.clientExtensions);
}
}
protected virtual byte[] GenerateServerHello(ServerHandshakeState state)
{
SecurityParameters securityParameters = state.serverContext.SecurityParameters;
MemoryStream buf = new MemoryStream();
{
ProtocolVersion server_version = state.server.GetServerVersion();
if (!server_version.IsEqualOrEarlierVersionOf(state.serverContext.ClientVersion))
{
throw new TlsFatalAlert(AlertDescription.internal_error);
}
// TODO Read RFCs for guidance on the expected record layer version number
// recordStream.setReadVersion(server_version);
// recordStream.setWriteVersion(server_version);
// recordStream.setRestrictReadVersion(true);
state.serverContext.SetServerVersion(server_version);
TlsUtilities.WriteVersion(state.serverContext.ServerVersion, buf);
}
buf.Write(securityParameters.ServerRandom, 0, securityParameters.ServerRandom.Length);
/*
* The server may return an empty session_id to indicate that the session will not be cached
* and therefore cannot be resumed.
*/
TlsUtilities.WriteOpaque8(TlsUtilities.EmptyBytes, buf);
int selectedCipherSuite = state.server.GetSelectedCipherSuite();
if (!Arrays.Contains(state.offeredCipherSuites, selectedCipherSuite) ||
selectedCipherSuite == CipherSuite.TLS_NULL_WITH_NULL_NULL ||
CipherSuite.IsScsv(selectedCipherSuite) ||
!TlsUtilities.IsValidCipherSuiteForVersion(selectedCipherSuite, state.serverContext.ServerVersion))
{
throw new TlsFatalAlert(AlertDescription.internal_error);
}
ValidateSelectedCipherSuite(selectedCipherSuite, AlertDescription.internal_error);
securityParameters.cipherSuite = selectedCipherSuite;
byte selectedCompressionMethod = state.server.GetSelectedCompressionMethod();
if (!Arrays.Contains(state.offeredCompressionMethods, selectedCompressionMethod))
{
throw new TlsFatalAlert(AlertDescription.internal_error);
}
securityParameters.compressionAlgorithm = selectedCompressionMethod;
TlsUtilities.WriteUint16(selectedCipherSuite, buf);
TlsUtilities.WriteUint8(selectedCompressionMethod, buf);
state.serverExtensions = state.server.GetServerExtensions();
/*
* RFC 5746 3.6. Server Behavior: Initial Handshake
*/
if (state.secure_renegotiation)
{
byte[] renegExtData = TlsUtilities.GetExtensionData(state.serverExtensions, ExtensionType.renegotiation_info);
bool noRenegExt = (null == renegExtData);
if (noRenegExt)
{
/*
* Note that sending a "renegotiation_info" extension in response to a ClientHello
* containing only the SCSV is an explicit exception to the prohibition in RFC 5246,
* Section 7.4.1.4, on the server sending unsolicited extensions and is only allowed
* because the client is signaling its willingness to receive the extension via the
* TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV.
*/
/*
* If the secure_renegotiation flag is set to TRUE, the server MUST include an empty
* "renegotiation_info" extension in the ServerHello message.
*/
state.serverExtensions = TlsExtensionsUtilities.EnsureExtensionsInitialised(state.serverExtensions);
state.serverExtensions[ExtensionType.renegotiation_info] = TlsProtocol.CreateRenegotiationInfo(TlsUtilities.EmptyBytes);
}
}
if (securityParameters.extendedMasterSecret)
{
state.serverExtensions = TlsExtensionsUtilities.EnsureExtensionsInitialised(state.serverExtensions);
TlsExtensionsUtilities.AddExtendedMasterSecretExtension(state.serverExtensions);
}
/*
* TODO RFC 3546 2.3 If [...] the older session is resumed, then the server MUST ignore
* extensions appearing in the client hello, and send a server hello containing no
* extensions.
*/
if (state.serverExtensions != null)
{
securityParameters.encryptThenMac = TlsExtensionsUtilities.HasEncryptThenMacExtension(state.serverExtensions);
securityParameters.maxFragmentLength = EvaluateMaxFragmentLengthExtension(state.resumedSession,
state.clientExtensions, state.serverExtensions, AlertDescription.internal_error);
securityParameters.truncatedHMac = TlsExtensionsUtilities.HasTruncatedHMacExtension(state.serverExtensions);
/*
* TODO It's surprising that there's no provision to allow a 'fresh' CertificateStatus to be sent in
* a session resumption handshake.
*/
state.allowCertificateStatus = !state.resumedSession &&
TlsUtilities.HasExpectedEmptyExtensionData(state.serverExtensions, ExtensionType.status_request,
AlertDescription.internal_error);
state.expectSessionTicket = !state.resumedSession &&
TlsUtilities.HasExpectedEmptyExtensionData(state.serverExtensions, ExtensionType.session_ticket,
AlertDescription.internal_error);
TlsProtocol.WriteExtensions(buf, state.serverExtensions);
}
securityParameters.prfAlgorithm = TlsProtocol.GetPrfAlgorithm(state.serverContext,
securityParameters.CipherSuite);
/*
* RFC 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());
}
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 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 (!Arrays.Contains(state.offeredCompressionMethods, 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 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)
{
{
/*
* 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.extendedMasterSecret = TlsExtensionsUtilities.HasExtendedMasterSecretExtension(sessionServerExtensions);
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);
}
/*
* 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)
*/
if (sessionClientExtensions != null)
{
state.client.ProcessServerExtensions(sessionServerExtensions);
}
securityParameters.prfAlgorithm = TlsProtocol.GetPrfAlgorithm(state.clientContext,
securityParameters.CipherSuite);
/*
* RFC 5246 7.4.9. Any cipher suite which does not explicitly specify verify_data_length has
* a verify_data_length equal to 12. This includes all existing cipher suites.
*/
securityParameters.verifyDataLength = 12;
}
protected virtual byte[] GenerateClientHello(ClientHandshakeState state, TlsClient client)
{
MemoryStream buf = new MemoryStream();
ProtocolVersion client_version = client.ClientVersion;
if (!client_version.IsDtls)
{
throw new TlsFatalAlert(AlertDescription.internal_error);
}
TlsClientContextImpl context = state.clientContext;
context.SetClientVersion(client_version);
TlsUtilities.WriteVersion(client_version, buf);
SecurityParameters securityParameters = context.SecurityParameters;
buf.Write(securityParameters.ClientRandom, 0, securityParameters.ClientRandom.Length);
// Session ID
byte[] session_id = TlsUtilities.EmptyBytes;
if (state.tlsSession != null)
{
session_id = state.tlsSession.SessionID;
if (session_id == null || session_id.Length > 32)
{
session_id = TlsUtilities.EmptyBytes;
}
}
TlsUtilities.WriteOpaque8(session_id, buf);
// Cookie
TlsUtilities.WriteOpaque8(TlsUtilities.EmptyBytes, buf);
bool fallback = client.IsFallback;
/*
* Cipher suites
*/
state.offeredCipherSuites = client.GetCipherSuites();
// Integer -> byte[]
state.clientExtensions = client.GetClientExtensions();
// Cipher Suites (and SCSV)
{
/*
* 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.
*/
byte[] renegExtData = TlsUtilities.GetExtensionData(state.clientExtensions, ExtensionType.renegotiation_info);
bool noRenegExt = (null == renegExtData);
bool noRenegSCSV = !Arrays.Contains(state.offeredCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV);
if (noRenegExt && noRenegSCSV)
{
// TODO Consider whether to default to a client extension instead
state.offeredCipherSuites = Arrays.Append(state.offeredCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV);
}
/*
* RFC 7507 4. If a client sends a ClientHello.client_version containing a lower value
* than the latest (highest-valued) version supported by the client, it SHOULD include
* the TLS_FALLBACK_SCSV cipher suite value in ClientHello.cipher_suites [..]. (The
* client SHOULD put TLS_FALLBACK_SCSV after all cipher suites that it actually intends
* to negotiate.)
*/
if (fallback && !Arrays.Contains(state.offeredCipherSuites, CipherSuite.TLS_FALLBACK_SCSV))
{
state.offeredCipherSuites = Arrays.Append(state.offeredCipherSuites, CipherSuite.TLS_FALLBACK_SCSV);
}
TlsUtilities.WriteUint16ArrayWithUint16Length(state.offeredCipherSuites, buf);
}
// TODO Add support for compression
// Compression methods
// state.offeredCompressionMethods = client.getCompressionMethods();
state.offeredCompressionMethods = new byte[] { CompressionMethod.cls_null };
TlsUtilities.WriteUint8ArrayWithUint8Length(state.offeredCompressionMethods, buf);
// Extensions
if (state.clientExtensions != null)
{
TlsProtocol.WriteExtensions(buf, state.clientExtensions);
}
return(buf.ToArray());
}
public virtual DtlsTransport Connect(TlsClient client, DatagramTransport transport)
{
if (client == null)
{
throw new ArgumentNullException("client");
}
if (transport == null)
{
throw new ArgumentNullException("transport");
}
SecurityParameters securityParameters = new SecurityParameters();
securityParameters.entity = ConnectionEnd.client;
ClientHandshakeState state = new ClientHandshakeState();
state.client = client;
state.clientContext = new TlsClientContextImpl(mSecureRandom, securityParameters);
securityParameters.clientRandom = TlsProtocol.CreateRandomBlock(client.ShouldUseGmtUnixTime(),
state.clientContext.NonceRandomGenerator);
client.Init(state.clientContext);
DtlsRecordLayer recordLayer = new DtlsRecordLayer(transport, state.clientContext, client, ContentType.handshake);
TlsSession sessionToResume = state.client.GetSessionToResume();
if (sessionToResume != null && sessionToResume.IsResumable)
{
SessionParameters sessionParameters = sessionToResume.ExportSessionParameters();
if (sessionParameters != null)
{
state.tlsSession = sessionToResume;
state.sessionParameters = sessionParameters;
}
}
try
{
return(ClientHandshake(state, recordLayer));
}
catch (TlsFatalAlert fatalAlert)
{
AbortClientHandshake(state, recordLayer, fatalAlert.AlertDescription);
throw fatalAlert;
}
catch (IOException e)
{
AbortClientHandshake(state, recordLayer, AlertDescription.internal_error);
throw e;
}
catch (Exception e)
{
AbortClientHandshake(state, recordLayer, AlertDescription.internal_error);
throw new TlsFatalAlert(AlertDescription.internal_error, e);
}
finally
{
securityParameters.Clear();
}
}
