Proof-of-Stake Protocols for Privacy-Aware Blockchains.

Proof-of-stake (PoS) protocols are emerging as one of the most promising alternative to the wasteful proof-of-work (PoW) protocols for consensus in Blockchains (or distributed ledgers). However, current PoS protocols inherently disclose both the identity and the wealth of the stakeholders, and thus seem incompatible with privacy-preserving cryptocurrencies (such as ZCash, Monero, etc.). In this paper we initiate the formal study for PoS protocols with privacy properties. Our results include: 1. A (theoretical) feasibility result showing that it is possible to construct a general class of private PoS (PPoS) protocols; and to add privacy to a wide class of PoS protocols, 2. A privacy-preserving version of a popular PoS protocol, Ouroboros Praos. Towards our result, we define the notion of anonymous verifiable random function, which we believe is of independent interest.