/// <summary>
///
/// </summary>
/// <param name="envelope"></param>
/// <param name="ciphertext"></param>
/// <returns></returns>
/// <exception cref="InvalidMetadataMessageException"></exception>
/// <exception cref="InvalidMetadataVersionException"></exception>
/// <exception cref="ProtocolDuplicateMessageException"></exception>
/// <exception cref="ProtocolUntrustedIdentityException"></exception>
/// <exception cref="ProtocolLegacyMessageException"></exception>
/// <exception cref="ProtocolInvalidKeyException"></exception>
/// <exception cref="ProtocolInvalidVersionException"></exception>
/// <exception cref="ProtocolInvalidMessageException"></exception>
/// <exception cref="ProtocolInvalidKeyIdException"></exception>
/// <exception cref="ProtocolNoSessionException"></exception>
/// <exception cref="SelfSendException"></exception>
private Plaintext Decrypt(SignalServiceEnvelope envelope, byte[] ciphertext)
{
try
{
byte[] paddedMessage;
SignalServiceMetadata metadata;
uint sessionVersion;
if (!envelope.HasSource() && !envelope.IsUnidentifiedSender())
{
throw new ProtocolInvalidMessageException(new InvalidMessageException("Non-UD envelope is missing a source!"), null, 0);
}
if (envelope.IsPreKeySignalMessage())
{
SignalProtocolAddress sourceAddress = GetPreferredProtocolAddress(signalProtocolStore, envelope.GetSourceAddress(), envelope.GetSourceDevice());
SessionCipher sessionCipher = new SessionCipher(signalProtocolStore, sourceAddress);
paddedMessage = sessionCipher.decrypt(new PreKeySignalMessage(ciphertext));
metadata = new SignalServiceMetadata(envelope.GetSourceAddress(), envelope.GetSourceDevice(), envelope.GetTimestamp(), false);
sessionVersion = sessionCipher.getSessionVersion();
}
else if (envelope.IsSignalMessage())
{
SignalProtocolAddress sourceAddress = GetPreferredProtocolAddress(signalProtocolStore, envelope.GetSourceAddress(), envelope.GetSourceDevice());
SessionCipher sessionCipher = new SessionCipher(signalProtocolStore, sourceAddress);
paddedMessage = sessionCipher.decrypt(new SignalMessage(ciphertext));
metadata = new SignalServiceMetadata(envelope.GetSourceAddress(), envelope.GetSourceDevice(), envelope.GetTimestamp(), false);
sessionVersion = sessionCipher.getSessionVersion();
}
else if (envelope.IsUnidentifiedSender())
{
SealedSessionCipher sealedSessionCipher = new SealedSessionCipher(signalProtocolStore, localAddress.Uuid, localAddress.GetNumber(), 1);
DecryptionResult result = sealedSessionCipher.Decrypt(certificateValidator !, ciphertext, (long)envelope.Envelope.ServerTimestamp);
SignalServiceAddress resultAddress = new SignalServiceAddress(UuidUtil.Parse(result.SenderUuid), result.SenderE164);
SignalProtocolAddress protocolAddress = GetPreferredProtocolAddress(signalProtocolStore, resultAddress, result.DeviceId);
paddedMessage = result.PaddedMessage;
metadata = new SignalServiceMetadata(resultAddress, result.DeviceId, envelope.GetTimestamp(), true);
sessionVersion = (uint)sealedSessionCipher.GetSessionVersion(protocolAddress);
}
else
{
throw new InvalidMessageException($"Unknown type: {envelope.GetType()}");
}
PushTransportDetails transportDetails = new PushTransportDetails(sessionVersion);
byte[] data = transportDetails.GetStrippedPaddingMessageBody(paddedMessage);
return(new Plaintext(metadata, data));
}
catch (DuplicateMessageException e)
{
throw new ProtocolDuplicateMessageException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
catch (LegacyMessageException e)
{
throw new ProtocolLegacyMessageException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
catch (InvalidMessageException e)
{
throw new ProtocolInvalidMessageException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
catch (InvalidKeyIdException e)
{
throw new ProtocolInvalidKeyIdException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
catch (InvalidKeyException e)
{
throw new ProtocolInvalidKeyException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
catch (libsignal.exceptions.UntrustedIdentityException e)
{
throw new ProtocolUntrustedIdentityException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
catch (InvalidVersionException e)
{
throw new ProtocolInvalidVersionException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
catch (NoSessionException e)
{
throw new ProtocolNoSessionException(e, envelope.GetSourceIdentifier(), envelope.GetSourceDevice());
}
}