Mitigating Channel Jamming with Reputation Credentials: a Protocol Sketch

Summary:

Antoine Riard, a developer of the Lightning Network Protocol, has proposed a "staking/reputational" credential system for the network. The proposed system would allow a routing hop to adopt a 0-risk HTLC forwarding acceptance policy with a direct link between credentials and a cost expressed in satoshis. This proposal is at the stage of a sketch and doesn't pretend more. Although one can opt into using this reputation system, it is open to criticism that an attacker could game the system. To address concerns, Antoine proposes fleshing out a protocol sketch, asking for wide community feedback, trying to break it themselves, proposing a new iteration, and doing it over and over until they reach a level of consistency and soundness convincing as many stakeholders as possible in the community.Antoine's proposed reputation-based scheme aims to solve channel jamming in the Lightning Network. The proposal relies on "credentials" issued by routing hops and requested to be attached to each HTLC forward request, which can be used by a reputation algorithm to reward/punish payment senders and allocate channel liquidity resources efficiently. Critics of the proposal argue that decentralized reputation systems baked into a protocol are difficult to manage effectively and prone to attacks where an innocent party is blamed. They also warn that decisions made by protocol developers will impact what data can be collected and how easy it is to collect. Reputation should be managed by multiple companies and projects, rather than protocol devs. The proposal builds on previous reputation-scheme research and integrates recent proposals of upfront fees as a straightforward mechanism to bootstrap the reputation system. The proposal aims to use reputation credentials to allow HTLC traffic-shaping and protect against jamming situations, while also allowing active HTLC traffic-shaping for extended channel liquidity lockups based on accumulated reputation. The mitigation is effective, incentive-compatible, transparent from the user, and conserves high-level privacy. Implementation requires few protocol messages to modify, a HTLC intercepting API, onion messages support, landing EC blinded signature in libsecp256k1-zkp, and routing algorithms adaptations. The "credentials-to-liquidity" allocation algorithms are likely the new real beast.In a recent proposal on the Lightning Development mailing list, Antoine Riard discusses the potential implementation of a reputation system for routing nodes in the Lightning Network (LN). The proposed system would track historical performance metrics and use them to determine trustworthiness in terms of successfully forwarding transactions. While this could introduce centralization inertia, it could also incentivize new routing hops to lower acquisition costs and attract more traffic. However, the proposal's ecosystem impacts on items such as inbound channel routing fees, ratecards, and flow-control valves must be studied to ensure that future LN protocol upgrades are not significantly restrained. Riard emphasizes modularity and flexibility in the proposed system, with each routing node having oversight over its routing policy, acquisition methods, credentials to liquidity rate, and the ability to experiment with new acquisition methods. Additionally, the credentials themselves could have an "innate" expiration time if short-lived ZKP is utilized. The framework could also be extended beyond solving jamming, serving as a generalized risk-management framework for Bitcoin decentralized financial networks. Feedback on the proposal is welcomed.

Updated on: 2023-06-03T10:42:56.834694+00:00