Reputation at Stake! A Trust Layer over Decentralized Ledger for Multiparty Computation and Reputation-Fair Lottery

Abstract

This work introduces, to the best of our knowledge, the first stake based reputation and trust layer to proof of stake (PoS) system. Namely, we show that the delegation framework, introduced by Karakostas et al. (SCN’20) to provide a delegation framework, can be extended and repurposed to construct a trust layer over a PoS consensus protocol in addition to its original application. Furthermore, we show a concrete reputation system satisfying the positive results of (1) Asharov et al. (Asiacrypt’13), allowing the secure execution of multiparty protocols such as GMW (STOC’ 87) and Damgard and Ishai (Crypto’05), and (2) Kleinrock et al. (Indocrypt’20), a Reputation-fair Lottery, thus, also, a Proof of Reputation system. More concretely, our devised layer is used to construct a concrete reputation system based on arbitrary stake distribution. In this layer groups of users can freely and dynamically “assign their respective trust” to members of a set of trustees, i.e. participants that offered themselves as receivers of such assignment. Furthermore, our work offers the advantage of providing a clear stake based criteria, verifiable in the ledger, and, therefore, naturally resistant to sybil attack, that the set of trustees indeed yields an honest majority. This setting provides a better situation than a simple assumption of honest majority, since it involves stake in a decentralized ledger, and the public verifiability of the reputation score via verification of the stake distribution.