Cable

Distributed systems development is hard. Doubly so when you have adopted a complicated technological stack in order to achieve the goals of a peer-to-peer group chat like Cabal. Some problems inherent in an approach can only be seen in hindsight, and repaired with foresight. Enter Cable, a new lightweight binary communication protocol originally specified to be the upcoming backbone of the peer-to-peer group chat Cabal.

The Cable protocol is pull-based, with message authenticity through cryptographic hashes, where peers receive messages by sending queries into the network: "give me the most recent week of chat messages in channel main". Peer-to-peer query-forwarding is built into the design to enable message retrieval outside any given peer's direct connections. Its logless approach enables message deletion and allows the many devices owned by a single person to use the same cryptographic identity in communication. The binary specification combined with the pull-based design minimizes system resources in transport and storage alike. Cable's goals as a protocol: to be compact over the wire, easy to implement from scratch with libsodium bindings as the only dependency, to enable bridging across any network transport, and to be agnostic with regard to how data is stored. In addition to unlocking new capabilities in Cabal's future, we also hope to pave the way for a multitude of other protocols to be hosted on Cable's agnostic wire format.