public byte[] Serialize <T>(CryptoDtoChannel channel, CryptoDtoMode mode, T obj)
{
ArrayBufferWriter <byte> arrayBufferWriter = new ArrayBufferWriter <byte>();
Serialize(arrayBufferWriter, channel, mode, obj);
return(arrayBufferWriter.WrittenSpan.ToArray());
}
internal Deserializer(CryptoDtoChannel channel, ushort headerLength, CryptoDtoHeaderDto header, ReadOnlySpan <byte> bytes, bool ignoreSequence, IBufferWriter <byte> plaintextBuffer)
{
sequenceValid = false;
channelTag = header.ChannelTag;
switch (header.Mode)
{
case CryptoDtoMode.ChaCha20Poly1305:
{
int adLength = 2 + headerLength;
int aeLength = bytes.Length - adLength - 16;
ReadOnlySpan <byte> ad = bytes.Slice(0, adLength);
ReadOnlySpan <byte> ae = bytes.Slice(adLength, aeLength);
ReadOnlySpan <byte> tag = bytes.Slice(adLength + aeLength, 16);
Span <byte> nonce = stackalloc byte[Aead.NonceSize];
BinaryPrimitives.WriteUInt64LittleEndian(nonce.Slice(4), header.Sequence);
var aead = channel.ReceiveChaCha20Poly1305;
Memory <byte> plaintext = plaintextBuffer.GetMemory(aeLength).Slice(0, aeLength);
aead.Decrypt(nonce, ae, tag, plaintext.Span, ad);
if (ignoreSequence)
{
sequenceValid = channel.IsReceivedSequenceAllowed(header.Sequence);
}
else
{
channel.CheckReceivedSequence(header.Sequence); //The packet has passed MAC, so now check if it's being duplicated or replayed
sequenceValid = true;
}
var dtoNameLength = Unsafe.ReadUnaligned <ushort>(ref MemoryMarshal.GetReference(plaintext.Span)); //.NET Standard 2.0 doesn't have BitConverter.ToUInt16(Span<T>)
if (plaintext.Length < (2 + dtoNameLength))
{
throw new CryptographicException("Not enough bytes to process packet. (2) " + dtoNameLength + " " + plaintext.Length);
}
dtoNameBuffer = plaintext.Span.Slice(2, dtoNameLength);
var dtoLength = Unsafe.ReadUnaligned <ushort>(ref MemoryMarshal.GetReference(plaintext.Span.Slice(2 + dtoNameLength, 2))); //.NET Standard 2.0 doesn't have BitConverter.ToUInt16(Span<T>)
if (plaintext.Length < (2 + dtoNameLength + 2 + dtoLength))
{
throw new CryptographicException("Not enough bytes to process packet. (3) " + dtoLength + " " + plaintext.Length);
}
dtoBuffer = plaintext.Slice(2 + dtoNameLength + 2, dtoLength);
break;
}
default:
throw new CryptographicException("Mode not recognised");
}
}
public static Deserializer Deserialize(IBufferWriter <byte> plaintextBuffer, CryptoDtoChannel channel, ReadOnlyMemory <byte> bytes)
{
var header = Deserializer.GetHeader(bytes, out ushort headerLength);
if (header.ChannelTag != channel.ChannelTag)
{
throw new CryptographicException("Channel Tag doesn't match provided Channel");
}
return(new Deserializer(channel, headerLength, header, bytes.Span, false, plaintextBuffer));
}
// Hint for callers using ArrayBufferWriter<byte> - output.WrittenSpan contains the serialised data
public void Serialize <T>(IBufferWriter <byte> output, CryptoDtoChannel channel, CryptoDtoMode mode, T dto)
{
lock (bufferLock)
{
ReadOnlySpan <byte> dtoNameBuffer = GetDtoNameBytes <T>();
dtoBuffer.Clear();
MessagePackSerializer.Serialize(dtoBuffer, dto);
Pack(output, channel, mode, dtoNameBuffer, dtoBuffer.WrittenSpan);
}
}
public void CreateChannel(string channelTag, int receiveSequenceHistorySize = 10)
{
lock (channelStoreLock)
{
if (channelStore.ContainsKey(channelTag))
{
throw new CryptographicException("Key tag already exists in store. (" + channelTag + ")");
}
channelStore[channelTag] = new CryptoDtoChannel(channelTag, receiveSequenceHistorySize);
}
}
public bool TryCreateChannel(string channelTag, int receiveSequenceHistorySize = 10)
{
lock (channelStoreLock)
{
if (channelStore.ContainsKey(channelTag))
{
return(false);
}
channelStore[channelTag] = new CryptoDtoChannel(channelTag, receiveSequenceHistorySize);
return(true);
}
}
public void Pack(IBufferWriter <byte> output, CryptoDtoChannel channel, CryptoDtoMode mode, ReadOnlySpan <byte> dtoNameBuffer, ReadOnlySpan <byte> dtoBuffer)
{
channel.GetTransmitKey(mode, out ulong sequenceToSend);
CryptoDtoHeaderDto header = new CryptoDtoHeaderDto
{
ChannelTag = channel.ChannelTag,
Mode = mode,
Sequence = sequenceToSend
};
Pack(output, header, channel.TransmitChaCha20Poly1305, dtoNameBuffer, dtoBuffer);
}
public bool TryGetChannel(string channelTag, out CryptoDtoChannel channel)
{
lock (channelStoreLock)
{
if (!channelStore.ContainsKey(channelTag))
{
channel = null;
return(false);
}
channel = channelStore[channelTag];
return(true);
}
}
public static Deserializer DeserializeIgnoreSequence(IBufferWriter <byte> plaintextBuffer, CryptoDtoChannel channel, ReadOnlyMemory <byte> bytes) //This is used for UDP channels where duplication is possible and the overhead of CryptographicException isn't acceptable. Use IsSequenceValid() in code to ignore the UDP packet.
{
var header = Deserializer.GetHeader(bytes, out ushort headerLength);
if (header.ChannelTag != channel.ChannelTag)
{
throw new CryptographicException("Channel Tag doesn't match provided Channel");
}
return(new Deserializer(channel, headerLength, header, bytes.Span, true, plaintextBuffer));
}
public static Deserializer DeserializeIgnoreSequence(CryptoDtoChannel channel, ReadOnlyMemory <byte> bytes) //This is used for UDP channels where duplication is possible and the overhead of CryptographicException isn't acceptable. Use IsSequenceValid() in code to ignore the UDP packet.
{
var plaintextBuffer = new ArrayBufferWriter <byte>();
return(DeserializeIgnoreSequence(plaintextBuffer, channel, bytes));
}
public static Deserializer Deserialize(CryptoDtoChannel channel, ReadOnlyMemory <byte> bytes)
{
var plaintextBuffer = new ArrayBufferWriter <byte>();
return(Deserialize(plaintextBuffer, channel, bytes));
}
