  As cryptographic tokens and altcoins are increasingly being built to serve as
utility tokens, the notion of useful work consensus protocols, as opposed to
number-crunching PoW consensus, is becoming ever more important. In such
contexts, users get rewards from the network after they have carried out some
specific task useful for the network. While in some cases the proof of some
utility or service can be proved, the majority of tasks are impossible to
verify. In order to deal with such cases, we design Proof-of-Prestige (PoP) - a
reward system that can run on top of Proof-of-Stake blockchains. PoP introduces
prestige which is a volatile resource and, in contrast to coins, regenerates
over time. Prestige can be gained by performing useful work, spent when
benefiting from services and directly translates to users minting power. PoP is
resistant against Sybil and Collude attacks and can be used to reward workers
for completing unverifiable tasks, while keeping the system free for the
end-users. We use two exemplar use-cases to showcase the usefulness of PoP and
we build a simulator to assess the cryptoeconomic behaviour of the system in
terms of prestige transfer between nodes.
