Version 3 transaction relay
Also covering Topologically Restricted Until Confirmation (TRUC)
Version 3 transaction relay is a proposal to allow transactions to opt-in to a modified set of transaction relay policies designed to prevent pinning attacks. Combined with package relay, these policies help enable the use of dynamic feerates with LN onchain transactions.
V3 transaction relay is a superset of standard transaction policy. That is, v3 transactions follow all rules for standard transactions (e.g. minimum and maximum transaction weights) while also adding some additional rules designed to allow transaction replacement while precluding transaction-pinning attacks. v3 transactions also require minor changes to the package RBF policy in order to maintain incentive compatibility with miners.
V3 transaction relay solves rule 3 transaction pinning and may allow the removal of the CPFP carve-out.
Version 3 transactions are used by ephemeral anchors.
Primary code and documentation
- New transaction policies (nVersion=3) for contracting protocols
- Opt In Topologically Restricted Until Confirmation Transactions For More Robust Fee-bumping
Optech newsletter and website mentions
2024
- Bitcoin Core #29242 lays the groundwork for package replace by fee with v3-compatible packages
- Research about historic use of anchor outputs for possibly imbuing them with v3 properties
- Ideas for post-v3 relay enhancements after cluster mempool is deployed
- Bitcoin Core #28948 adds support for (but does not enable) version 3 transaction relay
- Challenges opening zero-conf channels when using the initially allowed v3 transaction topology
- Idea to apply RBF rules to v3 transactions to allow removing CPFP carve-out for cluster mempool
- Proposed changes to LN for v3 relay and ephemeral anchors
- Discussion about cluster mempool and a need for a CPFP carve out replacement like v3 relay
- Discussion about LN anchors and v3 transaction relay proposal
- Discussion about the costs of pinning when v3 policies are used
2023
- Replacement cycle attacks not solved by current v3 transaction relay policies
- LN developer discussion about multiple relay policy topics, including v3 transaction relay
- Preventing coinjoin pinning with v3 transaction relay
2022
- 2022 year-in-review: v3 transaction relay
- Ephemeral anchors implementation as proposed extension to v3 transaction relay policy
- Comparing disabling non-replaceable transactions to disabling special v3 transaction relay rules
- Ephemeral anchors proposal built on v3 transaction relay proposal
- Proposed new transaction relay policies designed for LN-penalty
See also
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