public static byte[] SerializeCore(this XMessageMetaData m)
{
byte[] serialized = PocoSerializer.Begin()
.Append((byte)m.MessageType)
.Append(m.SenderLocalMessageId)
.Append(m.SenderPublicKey)
.Finish();
return(serialized);
}
public static XMessageMetaData DeserializeMessageMetadata(this byte[] messageMetadata)
{
var m = new XMessageMetaData();
var ser = PocoSerializer.GetDeserializer(messageMetadata);
m.MessageType = (MessageType)ser.MakeByte(0);
m.SenderLocalMessageId = ser.MakeInt32(1);
m.SenderPublicKey = ser.MakeByteArray(2);
return(m);
}
void EncryptWithStrategy(Message message, KeyMaterial64 keyMaterial, RoundsExponent roundsExponent, KeyMaterial64 initialMetadataKeyMaterial)
{
XMessageMetaData messageMetadata = new XMessageMetaData {
MessageType = message.MessageType
};
switch (message.MessageType)
{
case MessageType.Text:
message.TextCipher = EncryptTextToBytes(message.ThreadText, keyMaterial, roundsExponent);
messageMetadata.SenderLocalMessageId = int.Parse(message.Id);
break;
case MessageType.Media:
message.ImageCipher = this.ixdsCryptoService.DefaultEncrypt(message.ThreadMedia, keyMaterial);
messageMetadata.SenderLocalMessageId = int.Parse(message.Id);
break;
case MessageType.TextAndMedia:
case MessageType.File:
message.TextCipher = EncryptTextToBytes(message.ThreadText, keyMaterial, roundsExponent);
message.ImageCipher = this.ixdsCryptoService.DefaultEncrypt(message.ThreadMedia, keyMaterial);
messageMetadata.SenderLocalMessageId = int.Parse(message.Id);
break;
case MessageType.DeliveryReceipt:
case MessageType.ReadReceipt:
messageMetadata.SenderLocalMessageId = int.Parse(message.SenderLocalMessageId);
break;
default:
throw new Exception("Invalid MessageType");
}
if (initialMetadataKeyMaterial != null) // initialMetadataKeyMaterial is only for resend requests
{
messageMetadata.SenderPublicKey = this.profileViewModel.PublicKey;
message.MetaCipher = this.ixdsCryptoService.DefaultEncrypt(messageMetadata.SerializeCore(), initialMetadataKeyMaterial);
}
else
{
messageMetadata.SenderPublicKey = this.ixdsCryptoService.GetRandom(32).Result.X;
message.MetaCipher = this.ixdsCryptoService.DefaultEncrypt(messageMetadata.SerializeCore(), keyMaterial);
}
if (!message.MessageType.IsReceipt())
{
message.EncryptedE2EEncryptionKey = this.ixdsCryptoService.DefaultEncrypt(keyMaterial.GetBytes(), this.ixdsCryptoService.SymmetricKeyRepository.GetMasterRandomKey());
}
}
/// <summary>
/// Fully decrypts a message of all types, both control and content messages (including images), if an end-to-en-encryption key can be determined.
/// </summary>
async Task <Message> TryDecryptMessageToFindSenderEnryptDecryptionKeyAndSaveIt(XMessage xmessage)
{
try
{
IReadOnlyList <Identity> contacts = await this.repo.GetAllContacts();
var decryptedMessage = new Message
{
// XMessage fields
RecipientId = "1", // drop my Id
TextCipher = xmessage.TextCipher,
ImageCipher = xmessage.ImageCipher,
DynamicPublicKey = xmessage.DynamicPublicKey,
DynamicPublicKeyId = xmessage.DynamicPublicKeyId,
PrivateKeyHint = xmessage.PrivateKeyHint,
LocalMessageState = LocalMessageState.JustReceived,
SendMessageState = SendMessageState.None,
Side = MessageSide.You,
// This is what we try to decrypt here
MessageType = MessageType.None,
SenderId = null,
};
Response <CipherV2> decodeMetaResponse = this.ixdsCryptoService.BinaryDecodeXDSSec(xmessage.MetaCipher, null);
if (!decodeMetaResponse.IsSuccess)
{
return(null); // garbled, no chance, ignore!
}
foreach (Identity identity in contacts)
{
GetE2EDecryptionKeyResult getE2EDecryptionKeyResult = await this.e2eRatchet.GetEndToEndDecryptionKeyAsync(identity.Id, xmessage.DynamicPublicKey, xmessage.PrivateKeyHint);
if (getE2EDecryptionKeyResult.E2EDecryptionKeyType == E2EDecryptionKeyType.UnavailableDynamicPrivateKey)
{
continue; // there was a privateKeyHint != 0 in the message, but the dynamic private key was not in the ratchet for user in the loop
}
KeyMaterial64 keyMaterial64 = getE2EDecryptionKeyResult.E2EDecryptionKeyMaterial;
var decryptMetaResponse = this.ixdsCryptoService.BinaryDecrypt(decodeMetaResponse.Result, keyMaterial64, null);
if (!decryptMetaResponse.IsSuccess)
{
continue;
}
await this.e2eRatchet.SaveIncomingDynamicPublicKeyOnSuccessfulDecryptionAsync(identity.Id, xmessage.DynamicPublicKey,
xmessage.DynamicPublicKeyId);
XMessageMetaData metadata = decryptMetaResponse.Result.GetBytes().DeserializeMessageMetadata();
decryptedMessage.SenderId = identity.Id;
decryptedMessage.MessageType = metadata.MessageType;
decryptedMessage.SenderLocalMessageId = metadata.SenderLocalMessageId.ToString();
if (decryptedMessage.MessageType.IsReceipt())
{
return(decryptedMessage);
}
if (decryptedMessage.MessageType.IsContent())
{
if (decryptedMessage.MessageType == MessageType.Text || decryptedMessage.MessageType == MessageType.TextAndMedia || decryptedMessage.MessageType == MessageType.File)
{
// if the message has text, decrypt all text
var decodeTextResponse = this.ixdsCryptoService.BinaryDecodeXDSSec(xmessage.TextCipher, null);
if (!decodeTextResponse.IsSuccess)
{
return(null); // something is wrong, should have worked
}
var decrpytTextResponse = this.ixdsCryptoService.Decrypt(decodeTextResponse.Result, keyMaterial64, null);
if (!decrpytTextResponse.IsSuccess)
{
return(null); // something is wrong, should have worked
}
decryptedMessage.ThreadText = decrpytTextResponse.Result.Text;
}
if (decryptedMessage.MessageType == MessageType.Media || decryptedMessage.MessageType == MessageType.TextAndMedia || decryptedMessage.MessageType == MessageType.File)
{
// if the message has image content, decrypt the image content
var decodeImageResponse = this.ixdsCryptoService.BinaryDecodeXDSSec(xmessage.ImageCipher, null);
if (!decodeImageResponse.IsSuccess)
{
return(null); // something is wrong, should have worked
}
var decrpytImageResponse = this.ixdsCryptoService.BinaryDecrypt(decodeImageResponse.Result, keyMaterial64, null);
if (!decrpytImageResponse.IsSuccess)
{
return(null); // something is wrong, should have worked
}
decryptedMessage.ThreadMedia = decrpytImageResponse.Result.GetBytes();
}
decryptedMessage.EncryptedE2EEncryptionKey = this.ixdsCryptoService.DefaultEncrypt(keyMaterial64.GetBytes(), this.ixdsCryptoService.SymmetricKeyRepository.GetMasterRandomKey());
decryptedMessage.LocalMessageState = LocalMessageState.Integrated;
await this.repo.AddMessage(decryptedMessage);
}
else
{
throw new Exception($"Invalid MessageType {decryptedMessage.MessageType}");
}
return(decryptedMessage);
} // foreach
// If we are here, assume it's a new contact's message or RESENT message:
CipherV2 encryptedMetaData = decodeMetaResponse.Result;
KeyMaterial64 initialKey = this.e2eRatchet.GetInitialE2EDecryptionKey(xmessage.DynamicPublicKey);
var decryptInitialMetaResponse = this.ixdsCryptoService.BinaryDecrypt(encryptedMetaData, initialKey, null);
if (decryptInitialMetaResponse.IsSuccess)
{
XMessageMetaData initialMessageMetadata =
decryptInitialMetaResponse.Result.GetBytes().DeserializeMessageMetadata();
var incomingPublicKey = initialMessageMetadata.SenderPublicKey;
// If we received several resent messages, the first from that incoming contact has already produced that contact:
var contact = contacts.SingleOrDefault(c => ByteArrays.AreAllBytesEqual(c.StaticPublicKey, incomingPublicKey));
bool isIncomingContact = false;
if (contact == null)
{
// Create new contact and save it to make the ratchet work normally
isIncomingContact = true;
var date = DateTime.UtcNow;
var incomingContact = new Identity
{
Id = Guid.NewGuid().ToString(),
StaticPublicKey = incomingPublicKey,
ContactState = ContactState.Valid,
Name = "Anonymous",
FirstSeenUtc = date,
LastSeenUtc = date
};
await this.repo.AddContact(incomingContact);
contact = incomingContact;
}
await this.e2eRatchet.SaveIncomingDynamicPublicKeyOnSuccessfulDecryptionAsync(contact.Id, xmessage.DynamicPublicKey,
xmessage.DynamicPublicKeyId);
// add metadata to message
decryptedMessage.SenderId = contact.Id;
decryptedMessage.MessageType = initialMessageMetadata.MessageType;
decryptedMessage.SenderLocalMessageId = initialMessageMetadata.SenderLocalMessageId.ToString();
if (decryptedMessage.MessageType.IsContent())
{
var success = true;
GetE2EDecryptionKeyResult getE2EDecryptionKeyResult = await this.e2eRatchet.GetEndToEndDecryptionKeyAsync(contact.Id, xmessage.DynamicPublicKey, xmessage.PrivateKeyHint);
KeyMaterial64 keyMaterial64 = getE2EDecryptionKeyResult.E2EDecryptionKeyMaterial;
await this.e2eRatchet.GetEndToEndDecryptionKeyAsync(contact.Id, xmessage.DynamicPublicKey, xmessage.PrivateKeyHint);
if (decryptedMessage.MessageType == MessageType.Text || decryptedMessage.MessageType == MessageType.TextAndMedia)
{
// if the message has text, decrypt all text
var decodeTextResponse = this.ixdsCryptoService.BinaryDecodeXDSSec(xmessage.TextCipher, null);
if (!decodeTextResponse.IsSuccess)
{
success = false; // something is wrong, should have worked
}
else
{
var decrpytTextResponse = this.ixdsCryptoService.Decrypt(decodeTextResponse.Result, keyMaterial64, null);
if (!decrpytTextResponse.IsSuccess)
{
success = false; // something is wrong, should have worked
}
else
{
decryptedMessage.ThreadText = decrpytTextResponse.Result.Text;
}
}
}
if (decryptedMessage.MessageType == MessageType.Media || decryptedMessage.MessageType == MessageType.TextAndMedia)
{
// if the message has image content, decrypt the image content
var decodeImageResponse = this.ixdsCryptoService.BinaryDecodeXDSSec(xmessage.ImageCipher, null);
if (!decodeImageResponse.IsSuccess)
{
success = false; // something is wrong, should have worked
}
else
{
var decrpytImageResponse = this.ixdsCryptoService.BinaryDecrypt(decodeImageResponse.Result, keyMaterial64, null);
if (!decrpytImageResponse.IsSuccess)
{
success = false; // something is wrong, should have worked
}
else
{
decryptedMessage.ThreadMedia = decrpytImageResponse.Result.GetBytes();
}
}
}
if (success)
{
decryptedMessage.EncryptedE2EEncryptionKey = this.ixdsCryptoService.DefaultEncrypt(keyMaterial64.GetBytes(), this.ixdsCryptoService.SymmetricKeyRepository.GetMasterRandomKey());
decryptedMessage.LocalMessageState = LocalMessageState.Integrated;
await this.contactListManager.ChatWorker_ContactUpdateReceived(null, contact.Id);
await this.repo.AddMessage(decryptedMessage);
return(decryptedMessage);
}
else
{
if (isIncomingContact)
{
await this.repo.DeleteContacts(new[] { contact.Id }); // delete the just incoming contact if the was an error anyway.
}
return(null);
}
}
else
{
return(null);
}
}
// nope, resend request (I hope we don't loop here!)
string networkPayloadHash = NetworkPayloadHash.ComputeAsGuidString(xmessage.SerializedPayload);
if (!this._resendsRequested.Contains(networkPayloadHash))
{
var response = await this.chatClient.UploadResendRequest(new XResendRequest { Id = networkPayloadHash, RecipientId = null });
if (response.IsSuccess)
{
this._resendsRequested.Add(networkPayloadHash);
}
}
}
catch (Exception e)
{
this.logger.LogError(e.Message);
}
return(null);
}
