State channels (Timeout Fraud Problem)

[hswick]

The query/response mechanism seems like a good place for the use of state channels. However, the current issue is the data availability problem around the timeout mechanism.

Ex: Using a state channel verifier makes a query, solver sends a response. Verifier claims solver never sent a response within the time frame (5 blocks). Solver has chance to prove they are indeed still playing. This fraud proof mechanism happens on-chain. Incentives dictate verifier pulls this trick every single query/response round because they want to see the solver lose. Then each round ends up being on-chain anyways.

Summary - In order to use state channels for query/response need to solve timeout fraud problem.

[PhABC]

Would there be any way to have a "provenly public" message exchange? If each response has a chance of being observed by a third party, who could act as a witness, then players couldn't blame each others about not receiving a message. If a player claims that the other player is pretending not to receive/see the message, he could call a random witness and the faulty player would have their deposit slashed and distributed.

[hswick]

@PhABC something like that would be nice. Sounds a lot like a consensus or a blockchain 😉 Possibly something that had the properties we needed but not a full blockchain.
Maybe Plasma, sidechains??? Idk, just throwing things out there.

I had some ideas around using the task giver as a third party. EX: Solver sends message to both task giver and verifier. But that is definitely subject to sybil attacks/collusion. And I'm afraid wouldn't make a verifier not try to claim fraud each round anyways.

The problem requires some kind of other protocol besides Truebit.