Conditional Message Transfer Contract To Solve Jamming

The proposed framework presents a novel method to mitigate channel jamming in the Lightning Network by employing Bitcoin script capabilities. This solution enables channel counterparts to verify whether a specific message was exchanged off-chain at a predetermined blockchain time, serving as a universal clock. This verification is crucial for addressing the issue of channel jamming, particularly in determining the duration for which a Hashed Timelock Contract (HTLC) or Point Time-Locked Contract (PTLC) has been withheld. Consequently, this allows for the imposition of fees based on the withholding duration of the HTLC or PTLC.

The core of this mitigation strategy revolves around a series of special scripts that utilize adaptor signatures and timelocks, alongside an off-chain exchange of messages. The conditional message transfer contract (CMTC) forms the basis of this approach, with its execution contingent upon multiple and alternative proof paths: "message transfer success," "liveliness challenge," and "message transfer failure." Each path within the CMTC provides a mechanism for either party to reclaim withheld fees under specified conditions, such as the failure to deliver a preimage or being offline during critical periods.

In practice, the CMTC operates through encrypted contract execution transactions (CETs), each locked by a double adaptor point corresponding to specific temporal points within the agreed window. These CETs determine the payout of the withhold fee. For instance, if Bob fails to initiate a liveliness challenge or respond appropriately, he may lose out due to an equilibrium penalty fee. Conversely, Alice can engage in the liveliness challenge at each temporal point, potentially regaining parts of the withhold fee.

This solution also touches on broader applications and unresolved issues. It suggests possibilities for expanding this protocol to address three-party Discreet Log Contracts (DLCs) in a manner that avoids griefing, which could significantly enhance decentralized financial contracts on Bitcoin. However, the cryptographic correctness and cryptoeconomic equilibrium of these solutions still require further analysis to ensure their validity and effectiveness.

Finally, this post marks an initial formalization of ideas previously discussed in various forums, aiming to solve channel jamming without the need for complex mechanisms like blind signatures or garbled circuits. This simpler approach leverages existing script capabilities and offers a structured way to handle disputes and fee assignments in channel jamming scenarios.