nchat

mautrix-signal is a Matrix-Signal puppeting bridge. It allows users to interact with Signal through the Matrix protocol.

For detailed setup and usage instructions, refer to the official documentation at docs.mau.fi.

whatsmeow is a Go library designed to interface with the WhatsApp web multidevice API. It allows developers to automate WhatsApp interactions such as sending/receiving messages, managing groups, and handling app state.

Core capabilities include:

• Sending text and media messages to private chats and groups.
• Receiving all incoming messages.
• Group management (joining via invites, creating/using invite links, and receiving group change events).
• Managing typing notifications, delivery receipts, and read receipts.
• Reading and writing app state (e.g., contact lists, chat pin/mute status).
• Handling retry receipts for failed message decryption.
• Sending status messages (experimental).

Note: Broadcast list messages and calls are currently not supported.

Duchat is an implementation of a dummy chat protocol designed specifically for the development and testing of nchat. It allows developers to simulate chat interactions without needing to connect to real messaging services.

Note that Duchat is disabled by default in standard nchat builds and must be explicitly enabled during the build process.

The blockchain is a distributed ledger system used to maintain a consistent state across multiple participants. It manages three primary types of state:

1. Key-Value Storage: A persistent trie for storing and retrieving data.
2. Group State: Manages participants and their specific permissions (e.g., AddUsers, RemoveUsers).
3. Shared Key Information: Manages encryption keys shared among participants.

Security is enforced through cryptographic signatures, sequential block heights, and state proofs that validate the state after a block is applied.

For most use cases involving languages other than C++, Java, or .NET, it is recommended to use the TDLib JSON interface. This interface is accessible via any language capable of executing C functions.

The JSON interface follows semantic versioning: major versions are binary and backward compatible, but the underlying API may change between minor or patch versions. You can use the version option to ensure compatibility with specific TDLib versions.

All stb libraries are dual-licensed as Public Domain or MIT.

• Public Domain: You can use them for any purpose without legal obligation, though attribution is appreciated.
• MIT: Available for those who prefer a standard open-source license.

Because they are public domain, you can wrap these libraries in your own software and relicense your new library under any license you choose.

nchat uses a multi-threaded architecture to handle different communication protocols (e.g., Telegram).

1. Protocol Processing: Each protocol must implement a thread that processes RequestMessage objects received via its SendRequest() method.
2. Communication to Main App: Protocols communicate information back to the main application by passing ServiceMessage objects to its message handler. These messages are then processed in a worker thread.
3. Core Logic and UI: The central application logic resides in uimodel.cpp, while the user interface rendering is managed by the ui*view.cpp files.

When developing with the Clip Library, keep the following platform constraints in mind:

• General (32-bit vs 64-bit): If your application might run in both 32-bit and 64-bit versions simultaneously, avoid using platform-dependent data types (like size_t) within custom format data, as their size may change.
• Windows: There is a limited number of available clipboard formats on Windows.
• Linux: Requires libx11-dev/libX11-devel for text and libpng-dev/libpng-devel for images.

To prevent block creators from brute-forcing emojis, a two-phase commit-reveal protocol is used to generate an unpredictable emoji_hash.

Protocol Steps:

1. Setup: Each participant generates a random 32-byte nonce and calculates nonce_hash = SHA256(nonce).
2. Commit Phase: Participants broadcast their nonce_hash (signed). The system waits for all participants to commit.
3. Reveal Phase: Participants broadcast their original nonce (signed). The system verifies SHA256(revealed_nonce) == committed_hash.
4. Final Hash: emoji_hash = HMAC-SHA512(concatenated_sorted_nonces, blockchain_hash).

Implementation Details: Participants should only apply messages (including their own) when received from the server to ensure all clients see the same state. This ensures emojis are only displayed once all clients with reasonable connectivity can view them.