//Can we change the ChaCha20Poly1305 input to some kind of ICrypto interface or action with 'Encrypt' and 'Decrypt'?
private void Pack(IBufferWriter <byte> output, CryptoDtoHeaderDto header, ChaCha20Poly1305 crypto, ReadOnlySpan <byte> dtoNameBuffer, ReadOnlySpan <byte> dtoBuffer)
{
lock (bufferLock)
{
headerBuffer.Clear();
MessagePackSerializer.Serialize(headerBuffer, header);
ReadOnlySpan <byte> headerBytes = headerBuffer.WrittenSpan;
ushort headerLength = (ushort)headerBytes.Length;
BinaryPrimitives.WriteUInt16LittleEndian(headerLengthBytes, headerLength);
ushort dtoNameLength = (ushort)dtoNameBuffer.Length;
BinaryPrimitives.WriteUInt16LittleEndian(dtoNameLengthBytes, dtoNameLength);
ushort dtoLength = (ushort)dtoBuffer.Length;
BinaryPrimitives.WriteUInt16LittleEndian(dtoLengthBytes, dtoLength);
switch (header.Mode)
{
case CryptoDtoMode.ChaCha20Poly1305:
{
int adLength = 2 + headerLength;
int aeLength = 2 + dtoNameLength + 2 + dtoLength;
// Copy data into associated data buffer
adBuffer.Clear();
adBuffer.Write(headerLengthBytes);
adBuffer.Write(headerBytes);
// Copy data into authenticated encryption buffer
aeBuffer.Clear();
aeBuffer.Write(dtoNameLengthBytes);
aeBuffer.Write(dtoNameBuffer);
aeBuffer.Write(dtoLengthBytes);
aeBuffer.Write(dtoBuffer);
Span <byte> nonceSpan = new Span <byte>(nonceBytes);
BinaryPrimitives.WriteUInt64LittleEndian(nonceSpan.Slice(4), header.Sequence);
var adSpan = adBuffer.WrittenSpan;
var aeSpan = aeBuffer.WrittenSpan;
var cipherTextSpan = cipherText.Span.Slice(0, aeLength);
cipherTextSpan.Clear();
Span <byte> tagSpan = tagBuffer;
tagSpan.Clear();
crypto.Encrypt(nonceSpan, aeSpan, cipherTextSpan, tagSpan, adSpan);
output.Write(adSpan);
output.Write(cipherTextSpan);
output.Write(tagSpan);
break;
}
default:
throw new CryptographicException("Mode not recognised");
}
}
}
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 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);
}
