Zero-conf channels, also called turbo channels, are new single-funded channels where the funder gives some or all of their initial funds to the acceptor. Those funds are not secure until the channel open transaction receives a sufficient number of confirmations, so there’s no risk to the acceptor spending some of those funds back through the funder using the standard LN protocol.
For example, Alice has several BTC in an account at Bob’s custodial exchange. Alice asks Bob to open a new channel paying her 1.0 BTC. Because Bob trusts himself not to double-spend the channel he just opened, he can allow Alice to send 0.1 BTC through his node to third-party Carol even before the channel open transaction has received a single confirmation.
Zero-conf channels were in use via various ad hoc mechanisms prior to a standardized mechanisim for them being added to the LN protocol in 2022.
Primary code and documentation
Optech newsletter and website mentions
- LND 0.15.1-beta adds support for zero-conf channels
- Core Lightning 0.12 adds support for zero-conf channels
- LND #6816 adds documentation about how to use zero-conf channels
- LDK #1401 adds support for zero-conf channel opens
- BOLTs #910 adds an
- LDK #1311 adds support for SCID alias field useful for zero-conf channels
- 2021 year-in-review: zero-conf channel opens
- Rust-Lightning #1078 adds channel_type negotiation useful for zero-conf channels