A Predictable Incentive Mechanism for TrueBit
This addresses a specific drawback in blockchain-based computation verification for users and developers, making it incremental by refining an existing protocol.
The paper tackles the unpredictable profitability of participation in TrueBit's verification mechanism by proposing a new incentive scheme that randomly selects multiple solvers to share fees evenly and includes a proof of independent execution to deter computation pooling, resulting in more predictable rewards for participants.
TrueBit is a protocol that uses interactive verification to allow a resource-constrained computation environment like a blockchain to perform much larger computations than usual in a trusted way. As long as a single honest participant is present to verify the computation, an invalid computation cannot get accepted. In TrueBit, the presence of such a verifier is incentivised by randomly injected forced errors. Additionally, in order to counter sybil attacks, the reward for finding an error drops off exponentially with the number of challengers. The main drawback of this mechanism is that it makes it very hard to predict whether participation will be profitable or not. To even out the rewards, we propose to randomly select multiple solvers from a pool and evenly share the fees among them, while still allowing outside challengers. Furthermore, a proof of independent execution will make it harder to establish computation pools which share computation results.