Onion Messages

Onion messages are a Lightning Network feature that lets nodes send small encrypted messages across the network using the same onion routing that protects payments, but without moving any money. Each intermediate node peels one encryption layer, learning only the next hop, so neither the endpoints nor the content are visible to relays. They are the transport layer for BOLT 12 offers, a reusable payment request format.

Why it matters

Before onion messages, requesting an invoice required contact outside the network, such as a web server, which added a point of failure and surveillance. With them, invoices can be requested and delivered inside Lightning itself, enabling static, reusable offers that work like a permanent payment address without the privacy loss. The mechanism also opens the door to asynchronous payments for mobile wallets that are frequently offline. For bitcoin's medium-of-exchange ambitions this is plumbing that makes paying a person as simple as paying a server, with privacy closer to handing over cash than to card networks.

How it works

A sender wraps a message in nested encryption layers, one per hop, using the Sphinx construction. Blinded paths extend the privacy further: a recipient can publish a route whose final hops are cryptographically hidden, so even the sender never learns the recipient's node identity. Unlike payments, onion messages carry no fees and lock no liquidity, so nodes apply rate limits to prevent abuse.