InputDerivedKey32 CreatePasswordDerivedKeyWithBCrypt(IV16 iv, KeyMaterial64 keyMaterial64, RoundsExponent roundsExponent,
LongRunningOperationContext context)
{
var leftSHA512 = new byte[32];
var rightSHA512 = new byte[32];
Buffer.BlockCopy(keyMaterial64.GetBytes(), 0, leftSHA512, 0, 32);
Buffer.BlockCopy(keyMaterial64.GetBytes(), 32, rightSHA512, 0, 32);
context.EncryptionProgress.Message = LocalizableStrings.MsgProcessingKey;
// Compute the left side on a ThreadPool thread
var task = Task.Run(() => BCrypt.CreateHash(iv, leftSHA512, roundsExponent.Value, context));
// Compute the right side after dispatching the work for the right side
BCrypt24 rightBCrypt = BCrypt.CreateHash(iv, rightSHA512, roundsExponent.Value, context);
// Wait for the left side result
task.Wait(context.CancellationToken);
// Use the results
var combinedHashes = ByteArrays.Concatenate(keyMaterial64.GetBytes(), task.Result.GetBytes(), rightBCrypt.GetBytes());
Debug.Assert(combinedHashes.Length == 64 + 24 + 24);
var condensedHash = this._platform.ComputeSHA256(combinedHashes);
return(new InputDerivedKey32(condensedHash));
}
InputDerivedKey32 CreateDerivedKeyWithSHA256(IV16 iv, KeyMaterial64 keyMaterial64)
{
var keyMaterial = ByteArrays.Concatenate(iv.GetBytes(), keyMaterial64.GetBytes());
var derivedKey = this._platform.ComputeSHA256(keyMaterial);
return(new InputDerivedKey32(derivedKey));
}
/// <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);
}
CipherV2 EncryptCommon(KeyMaterial64 keyMaterial64, RoundsExponent roundsExponent, LongRunningOperationContext context,
Compressed compressed)
{
if (context == null)
{
context = new LongRunningOperation(progress => { }, () => { }).Context;
}
if (this._log)
{
Debug.WriteLine("KeyMaterial64:");
Debug.WriteLine(keyMaterial64.GetBytes().ToHexView(false));
}
if (this._log)
{
Debug.WriteLine("Compressed:");
Debug.WriteLine(compressed.GetBytes().ToHexView(false));
}
PaddedData paddedData = this._internal.ApplyRandomPadding(compressed);
if (this._log)
{
Debug.WriteLine("PaddedData:");
Debug.WriteLine(paddedData.GetBytes().ToHexView(false));
Debug.WriteLine("PlainTextPadding:");
Debug.WriteLine(paddedData.PlaintextPadding);
}
IV16 iv = new IV16(this._platform.GenerateRandomBytes(16));
if (this._log)
{
Debug.WriteLine("IV16:");
Debug.WriteLine(iv.GetBytes().ToHexView(false));
}
InputDerivedKey32 inputDerivedKey = roundsExponent.Value == RoundsExponent.DontMakeRounds
? CreateDerivedKeyWithSHA256(iv, keyMaterial64)
: CreatePasswordDerivedKeyWithBCrypt(iv, keyMaterial64, roundsExponent, context);
if (this._log)
{
Debug.WriteLine("InputDerivedKey32:");
Debug.WriteLine(inputDerivedKey.GetBytes().ToHexView(false));
}
RandomKey32 randomKey = new RandomKey32(this._platform.GenerateRandomBytes(32));
if (this._log)
{
Debug.WriteLine("RandomKey32:");
Debug.WriteLine(randomKey.GetBytes().ToHexView(false));
}
XDSSecAPIInternal.IVCache ivCache = roundsExponent.Value == RoundsExponent.DontMakeRounds
? null
: this._internal.CreateIVTable(iv, roundsExponent.Value);
var cipherV2 = new CipherV2 {
RoundsExponent = roundsExponent, IV16 = iv
};
this._internal.AESEncryptRandomKeyWithInputDerivedKey(inputDerivedKey, randomKey, cipherV2, ivCache, context);
if (this._log)
{
Debug.WriteLine("RandomKeyCipher32:");
Debug.WriteLine(cipherV2.RandomKeyCipher32.GetBytes().ToHexView(false));
}
this._internal.AESEncryptMessageWithRandomKey(paddedData, randomKey, cipherV2, ivCache, context);
if (this._log)
{
Debug.WriteLine("MessageCipher:");
Debug.WriteLine(cipherV2.MessageCipher.GetBytes().ToHexView(false));
}
MAC16 mac = CreateMAC(cipherV2, context);
if (this._log)
{
Debug.WriteLine("MAC16:");
Debug.WriteLine(mac.GetBytes().ToHexView(false));
}
this._internal.AESEncryptMACWithRandomKey(cipherV2, mac, randomKey, ivCache, context);
if (this._log)
{
Debug.WriteLine("MACCipher16:");
Debug.WriteLine(cipherV2.MACCipher16.GetBytes().ToHexView(false));
}
return(cipherV2);
}
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>
/// Changes the master password by encrypting the master random key with a new password and updating the key file.
/// </summary>
/// <param name="currentMasterPassword">The current master password.</param>
/// <param name="futureMasterPassword">The future master password.</param>
/// <returns></returns>
public async Task ChangeMasterPasswordAsync(string currentMasterPassword, string futureMasterPassword)
{
// Verify the user knows the current master password
await TryLoadDecryptAndSetMasterRandomKeyAsync(currentMasterPassword, null);
KeyMaterial64 futureMasterPasswordHash = CreateKeyMaterialFromPassphrase(futureMasterPassword);
// get the current master random key in plaintext
KeyMaterial64 currentPlaintextMasterRandomKey = this.xdsCryptoService.SymmetricKeyRepository.GetMasterRandomKey();
// encrypt the current master random key for saving in the key file and write the file.
CipherV2 encryptedMasterRandomKey = this.xdsCryptoService.BinaryEncrypt(new Clearbytes(currentPlaintextMasterRandomKey.GetBytes()), futureMasterPasswordHash, new RoundsExponent(10), null).Result;
byte[] encryptedMasterRandomKeyBytes = this.xdsCryptoService.BinaryEncodeXDSSec(encryptedMasterRandomKey, null).Result;
await this.repo.WriteSpecialFile(MasterKeyFilename, encryptedMasterRandomKeyBytes);
}
async Task EncryptAndSaveDeviceVaultKeyAsync(KeyMaterial64 masterRandomKey, KeyMaterial64 masterPassphraseKeyMaterial, LongRunningOperationContext context)
{
context.EncryptionProgress.Message = "Encrypting master random key";
context.EncryptionProgress.Report(context.EncryptionProgress);
CipherV2 encryptedMasterRandomKey = this.xdsCryptoService.BinaryEncrypt(new Clearbytes(masterRandomKey.GetBytes()), masterPassphraseKeyMaterial, new RoundsExponent(10), context).Result;
byte[] encryptedMasterRandomKeyBytes = this.xdsCryptoService.BinaryEncodeXDSSec(encryptedMasterRandomKey, context).Result;
await this.repo.WriteSpecialFile(MasterKeyFilename, encryptedMasterRandomKeyBytes);
}