Uniform.Matrix.Protocol.Crypto 0.1.2

Uniform.Matrix.Protocol.Crypto

Matrix end-to-end encryption in pure .NET: Olm and Megolm, device keys, cross-signing, secret storage, server-side key backup with a recovery key, key requests between own devices, and emoji (SAS) verification. No native libraries; the curves come from BouncyCastle.

dotnet add package Uniform.Matrix.Protocol.Crypto

Encrypt a room

OlmMachine does the protocol work for one device. It talks to the server through IKeyTransport; Uniform.Matrix.Client has MatrixKeyTransport over a logged-in MatrixClient.

using Uniform.Matrix.Protocol.Crypto;

using OlmMachine machine = await OlmMachine.CreateAsync(new MatrixKeyTransport(client), new InMemoryCryptoStore(), client.UserId!, client.DeviceId!, pickleKey);
await machine.UploadInitialKeysAsync();

// Every sync goes through the machine: to-device messages, device lists, one-time key counts
await machine.ReceiveSyncAsync(sync);

// Send encrypted, and decrypt what arrives
EncryptedContent content = await machine.EncryptRoomEventAsync(roomId, EventTypes.RoomMessage, new MessageContent { MessageType = MessageTypes.Text, Body = "secret" }, memberIds);
await client.SendEventAsync(roomId, EventTypes.RoomEncrypted, content);
RoomEventDecryption result = await machine.DecryptRoomEventAsync(roomId, clientEvent);

SetUpRecoveryAsync creates cross-signing keys, a key backup and the recovery key; RecoverAsync restores them on a new login. RequestVerificationAsync, AcceptVerificationAsync and ConfirmVerificationAsync run emoji verification.

Olm and Megolm directly

using MegolmOutboundSession outbound = MegolmOutboundSession.Create();
using MegolmInboundSession inbound = MegolmInboundSession.FromSessionKey(outbound.SessionKey);

string ciphertext = outbound.Encrypt("hello");
MegolmPlaintext plaintext = inbound.Decrypt(ciphertext);
Console.WriteLine(plaintext.Text); // hello

OlmAccount and OlmSession cover Olm. Pickles use vodozemac's format, so state moves between the two implementations.

Notes

• The Olm and Megolm code is a C# port of vodozemac 0.11.1, and is tested against vodozemac itself. Unlike vodozemac, it has not been audited, and .NET cannot guarantee constant-time code or wipe all secrets from memory.
• Licensed MIT AND Apache-2.0: the vodozemac-derived files stay under the Apache License 2.0, whose text and the notices are included in the package.

About

Part of Uniform.Matrix, a pure .NET implementation of the Matrix specification. Version 0.1 is an early pre-release: APIs may still change.

• Architecture
• Building and testing