/// <param name="ack1SdIsReady">
/// =true for SD in ACK2
/// =false for SD in ACK1 (since the SessionDescription is not initialized yet)
/// </param>
internal byte[] Encrypt(ICryptoLibrary cryptoLibrary, InviteRequestPacket req, InviteAck1Packet ack1, InviteSession session,
bool ack1SdIsReady
)
{
BinaryProcedures.CreateBinaryWriter(out var ms, out var w);
w.Write(Flags);
UserCertificate.Encode(w, false);
BinaryProcedures.EncodeIPEndPoint(w, DirectChannelEndPoint);
NatBehaviour.Encode(w);
DirectChannelToken32.Encode(w);
w.Write((byte)SessionType);
UserCertificateSignature.Encode(w);
var bytesInLastBlock = (int)ms.Position % CryptoLibraries.AesBlockSize;
if (bytesInLastBlock != 0)
{
var bytesRemainingTillFullAesBlock = CryptoLibraries.AesBlockSize - bytesInLastBlock;
w.Write(cryptoLibrary.GetRandomBytes(bytesRemainingTillFullAesBlock));
}
var plainTextSdData = ms.ToArray();
var encryptedSdData = new byte[plainTextSdData.Length];
#region key, iv
BinaryProcedures.CreateBinaryWriter(out var ms2, out var w2);
req.GetSharedSignedFields(w2);
ack1.GetSharedSignedFields(w2, ack1SdIsReady);
var iv = cryptoLibrary.GetHashSHA256(ms2.ToArray()).Take(16).ToArray();
ms2.Write(session.SharedInviteAckDhSecret, 0, session.SharedInviteAckDhSecret.Length);
var aesKey = cryptoLibrary.GetHashSHA256(ms2.ToArray()); // here SHA256 is used as KDF, together with common fields from packets, including both ECDH public keys and timestamp
#endregion
cryptoLibrary.ProcessAesCbcBlocks(true, aesKey, iv, plainTextSdData, encryptedSdData);
return(encryptedSdData);
}
/// <param name="receivedFromUser">comes from local contact book. is null if it is contact invitation</param>
internal static InviteSessionDescription Decrypt_Verify(ICryptoLibrary cryptoLibrary, byte[] encryptedSdData,
InviteRequestPacket req,
InviteAck1Packet ack1,
bool ack1SdIsReady,
InviteSession session,
UserId receivedFromUserNullable,
DateTime localTimeNowUtc
)
{
#region key, iv
BinaryProcedures.CreateBinaryWriter(out var ms2, out var w2);
req.GetSharedSignedFields(w2);
ack1.GetSharedSignedFields(w2, ack1SdIsReady);
var iv = cryptoLibrary.GetHashSHA256(ms2.ToArray()).Take(16).ToArray();
ms2.Write(session.SharedInviteAckDhSecret, 0, session.SharedInviteAckDhSecret.Length);
var aesKey = cryptoLibrary.GetHashSHA256(ms2.ToArray()); // here SHA256 is used as KDF, together with common fields from packets, including both ECDH public keys and timestamp
#endregion
// decrypt
var plainTextSdData = new byte[encryptedSdData.Length];
cryptoLibrary.ProcessAesCbcBlocks(false, aesKey, iv, encryptedSdData, plainTextSdData);
var r = new InviteSessionDescription();
var reader = BinaryProcedures.CreateBinaryReader(plainTextSdData, 0);
r.Flags = reader.ReadByte();
if ((r.Flags & FlagsMask_MustBeZero) != 0)
{
throw new NotImplementedException();
}
r.UserCertificate = UserCertificate.Decode_AssertIsValidNow(reader, cryptoLibrary, receivedFromUserNullable, localTimeNowUtc);
r.DirectChannelEndPoint = BinaryProcedures.DecodeIPEndPoint(reader);
r.NatBehaviour = NatBehaviourModel.Decode(reader);
r.DirectChannelToken32 = DirectChannelToken32.Decode(reader);
r.SessionType = (SessionType)reader.ReadByte();
r.UserCertificateSignature = UserCertificateSignature.DecodeAndVerify(reader, cryptoLibrary,
w =>
{
req.GetSharedSignedFields(w);
ack1.GetSharedSignedFields(w, ack1SdIsReady);
r.WriteSignedFields(w);
},
r.UserCertificate);
return(r);
}
internal void DeriveSharedPingPongHmacKey(InviteRequestPacket req, InviteAck1Packet ack1, InviteAck2Packet ack2, InviteConfirmationPacket cfm)
{
if (SharedInviteAckDhSecret == null)
{
throw new NotImplementedException();
}
PacketProcedures.CreateBinaryWriter(out var ms, out var w);
req.GetSharedSignedFields(w);
ack1.GetSharedSignedFields(w, true);
ack2.GetSharedSignedFields(w);
cfm.GetSharedSignedFields(w);
w.Write(SharedInviteAckDhSecret);
SharedPingPongHmacKey = _localDrpPeer.CryptoLibrary.GetHashSHA256(ms.ToArray());
}
/// <summary>
/// sends INVITE, autenticates users, returns Session to be used to create direct cannel
/// </summary>
/// <param name="responderUserId">
/// comes from local contact book
/// </param>
/// <param name="responderRegId">
/// comes from local contact book
/// </param>
/// <param name="loggerCb">may be invoked more than one time (in case of retrying)</param>
public async Task <InviteSession> SendInviteAsync(UserCertificate requesterUserCertificate, RegistrationId responderRegistrationId, UserId responderUserId,
SessionType sessionType, Action <Logger> loggerCb = null)
{
InviteSession session = null;
try
{
var sw = Stopwatch.StartNew();
RoutedRequest routedRequest = null;
int trialsCount = 0;
Exception latestTriedNeighborException = null;
_retry:
trialsCount++;
session = new InviteSession(this);
var req = new InviteRequestPacket
{
NumberOfHopsRemaining = InviteRequestPacket.MaxNumberOfHopsRemaining,
RequesterEcdhePublicKey = new EcdhPublicKey(session.LocalInviteAckEcdhePublicKey),
RequesterRegistrationId = this.Configuration.LocalPeerRegistrationId,
ResponderRegistrationId = responderRegistrationId,
ReqTimestamp32S = Engine.Timestamp32S,
};
var logger = new Logger(Engine, this, req, DrpPeerEngine.VisionChannelModuleName_inv_requesterSide);
if (!Engine.RecentUniqueInviteRequests.Filter(req.GetUniqueRequestIdFields))
{
if (trialsCount > 50)
{
throw new NonUniquePacketFieldsException($"could not find unique fields to send INVITE request");
}
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"waiting a second to generate ne wunique INVITE request");
}
await Engine.EngineThreadQueue.WaitAsync(TimeSpan.FromSeconds(1), "inv_wait_1236");
goto _retry;
}
session.Logger = logger;
loggerCb?.Invoke(logger);
Engine.RecentUniquePublicEcdhKeys.AssertIsUnique(req.RequesterEcdhePublicKey.Ecdh25519PublicKey, "req.RequesterEcdhePublicKey");
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"generated unique ECDH key {req.RequesterEcdhePublicKey}");
}
req.RequesterRegistrationSignature = RegistrationSignature.Sign(Engine.CryptoLibrary, req.GetSharedSignedFields, this.Configuration.LocalPeerRegistrationPrivateKey);
this.TestDirection(logger, req.ResponderRegistrationId);
routedRequest = new RoutedRequest(logger, null, null, null, req, null, routedRequest);
// find best connected peer to send the request
var destinationPeer = Engine.RouteInviteRequest(this, routedRequest);
if (destinationPeer == null)
{
if (latestTriedNeighborException == null)
{
throw new NoNeighborsToSendInviteException();
}
else
{
throw latestTriedNeighborException;
}
}
InviteAck1Packet ack1;
try
{
var reqUdpData = req.Encode_SetP2pFields(destinationPeer);
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"sending {req} (ReqTimestamp32S={MiscProcedures.Uint32secondsToDateTime(req.ReqTimestamp32S)}), waiting for NPACK");
}
var sentRequest = new SentRequest(Engine, logger, destinationPeer.RemoteEndpoint, destinationPeer, reqUdpData, req.ReqP2pSeq16, InviteAck1Packet.GetScanner(logger, req, destinationPeer));
var ack1UdpData = await sentRequest.SendRequestAsync("ack1 4146");
#region process ACK1
// NeighborHMAC and NeighborToken32 are already verified by scanner
ack1 = InviteAck1Packet.Decode(ack1UdpData);
Engine.RecentUniquePublicEcdhKeys.AssertIsUnique(ack1.ResponderEcdhePublicKey.Ecdh25519PublicKey, $"ack1.ResponderEcdhePublicKey");
if (!ack1.ResponderRegistrationSignature.Verify(Engine.CryptoLibrary, w =>
{
req.GetSharedSignedFields(w);
ack1.GetSharedSignedFields(w, true);
},
responderRegistrationId))
{
throw new BadSignatureException("invalid REGISTER ACK1 ResponderRegistrationSignature 2349");
}
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"verified ACK1");
}
session.DeriveSharedInviteAckDhSecret(Engine.CryptoLibrary, ack1.ResponderEcdhePublicKey.Ecdh25519PublicKey);
// send NPACK to ACK1
SendNeighborPeerAckResponseToAck1(ack1, destinationPeer);
#endregion
}
catch (RequestFailedException exc2)
{
latestTriedNeighborException = exc2;
if (trialsCount > 50)
{
throw;
}
logger.WriteToLog_higherLevelDetail($"trying again on error {exc2.Message}... alreadyTriedProxyingToDestinationPeers.Count={routedRequest.TriedNeighbors.Count}");
routedRequest.TriedNeighbors.Add(destinationPeer);
goto _retry;
}
// decode and verify SD
session.RemoteSessionDescription = InviteSessionDescription.Decrypt_Verify(Engine.CryptoLibrary,
ack1.ToResponderSessionDescriptionEncrypted,
req, ack1, false, session,
responderUserId, Engine.DateTimeNowUtc);
// sign and encode local SD
session.LocalSessionDescription = new InviteSessionDescription
{
DirectChannelEndPoint = destinationPeer.LocalEndpoint,
SessionType = sessionType,
DirectChannelToken32 = session.LocalDirectChannelToken32
};
session.LocalSessionDescription.UserCertificate = requesterUserCertificate;
session.LocalSessionDescription.UserCertificateSignature = UserCertificateSignature.Sign(Engine.CryptoLibrary,
w =>
{
req.GetSharedSignedFields(w);
ack1.GetSharedSignedFields(w, true);
session.LocalSessionDescription.WriteSignedFields(w);
},
requesterUserCertificate
);
#region send ack2
var ack2 = new InviteAck2Packet
{
RequesterRegistrationId = req.RequesterRegistrationId,
ResponderRegistrationId = req.ResponderRegistrationId,
ReqTimestamp32S = req.ReqTimestamp32S,
ToRequesterSessionDescriptionEncrypted = session.LocalSessionDescription.Encrypt(Engine.CryptoLibrary, req, ack1, session, true)
};
ack2.RequesterRegistrationSignature = RegistrationSignature.Sign(Engine.CryptoLibrary, w =>
{
req.GetSharedSignedFields(w);
ack1.GetSharedSignedFields(w, true);
ack2.GetSharedSignedFields(w);
}, this.Configuration.LocalPeerRegistrationPrivateKey);
var ack2UdpData = ack2.Encode_SetP2pFields(destinationPeer);
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"sending ACK2, waiting for NPACK");
}
await destinationPeer.SendUdpRequestAsync_Retransmit_WaitForNPACK("ack2 234575672", ack2UdpData, ack2.ReqP2pSeq16, ack2.GetSignedFieldsForNeighborHMAC);
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"received NPACK");
}
#endregion
#region wait for CFM
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"waiting for CFM");
}
var cfmUdpData = await Engine.WaitForUdpResponseAsync(new PendingLowLevelUdpRequest("cfm 1235695", destinationPeer.RemoteEndpoint,
InviteConfirmationPacket.GetScanner(logger, req, destinationPeer),
Engine.DateTimeNowUtc, Engine.Configuration.CfmTimoutS
));
if (cfmUdpData == null)
{
throw new DrpTimeoutException($"did not get CFM at invite requester from destination peer {destinationPeer} (timeout={Engine.Configuration.CfmTimoutS}s)");
}
// NeighborHMAC and NeighborToken32 are already verified by scanner
var cfm = InviteConfirmationPacket.Decode(cfmUdpData);
if (!cfm.ResponderRegistrationSignature.Verify(Engine.CryptoLibrary, w =>
{
req.GetSharedSignedFields(w);
ack1.GetSharedSignedFields(w, true);
ack2.GetSharedSignedFields(w);
},
responderRegistrationId))
{
throw new BadSignatureException("invalid REGISTER CFM ResponderRegistrationSignature 6398");
}
if (logger.WriteToLog_detail_enabled)
{
logger.WriteToLog_detail($"verified CFM");
}
// send NPACK to CFM
SendNeighborPeerAckResponseToCfm(cfm, destinationPeer);
#endregion
session.DeriveSharedPingPongHmacKey(req, ack1, ack2, cfm);
return(session);
}
catch
{
session?.Dispose();
throw;
}
}