Author: Subhra Mazumdar 2020-01-28 05:24:27
Published on: 2020-01-28T05:24:27+00:00
The Lightning Network protocol was discussed, and it was noted that the AMCU technique violated relationship anonymity. This technique compromises privacy to achieve atomicity and reduced collateral while also providing a notion of accountability. However, this trade-off could potentially make the Lightning Network unusable. The AMCU paper outlines how any off-chain updateable cryptocurrency system can host any contract that the hosting cryptocurrency system can host, including instances of itself. Participants in this system follow the protocol rules, culminating in a transaction that spends the funds of the sub-channel to whatever set of contracts was agreed upon as the latest channel state.To close the sub-channel, particular protocol rules need to be followed, culminating in a transaction that spends the fund of the sub-channel to the latest agreed-upon set of contracts. Off-chain updateable cryptocurrency systems implement a cut-through mechanism where presenting a valid transaction to the participants should be enough to convince them to delete those spent outputs and replace them with the outputs of that transaction in the next state of the off-chain cryptocurrency system.Cryptocurrency systems allow for the creation and destruction of UTXOs, making both blockchains and payment channels cryptocurrency systems. The difference lies in the coins they can safely store, as blockchains can safely store coins held by anyone, while payment channels can only safely store coins held by participants in the channel. The AMCU technique is measured against its ability to be implemented on-chain to enable a multi-participant CoinSwap. However, from a skim of the AMCU paper, it seems like all intermediate hops need to validate that all other intermediate hops follow the protocol, which would require presenting all transactions involved. This implies that all intermediate hops know the entire route, which is bad for privacy.The paper "Atomic multi-channel updates with constant collateral in bitcoin-compatible payment-channel networks" describes a setup phase requiring freezing coins available at each channel involved in the protocol. During this phase, the balance at each payment channel is split into two sub-channels: one with coins required for the present protocol session, and the other with remaining coins that can be freely spent. Operations at each channel during this phase can be carried out in parallel. Parties apply a condition on a fraction of channel funds to ensure a successful payment, but the entire channel fund is held when this occurs. The concept of subchannels of a single channel has been suggested in the paper, but it is still unclear what happens during closing of the subchannel.
Updated on: 2023-06-02T22:47:57.694028+00:00