The “lightning-onion” repository provides an implementation of the Lightning Network’s onion routing protocol, enabling secure and private routing of Hash-Time-Locked Contracts (HTLCs) across the network. This protocol empowers users with source-routing capabilities, allowing them to define routes, cumulative fees, and time-locks, enhancing control and efficiency. It upholds Bitcoin’s decentralization ethos by integrating an onion routing scheme that conceals payment destinations and participant details to safeguard against censorship. Employing a Sphinx-derived message format, the protocol includes modifications such as a MAC for enhanced security, streamlined packet size by removing unnecessary payloads, and the use of chacha20 as a stream cipher. Further, the mix-header is augmented with a per-hop payload for precise forwarding instructions, facilitating robust and responsive payment channel linkages. The repository aims to expand with the addition of HORNET’s application-specific implementation, enhancing the system’s functionality and privacy features.