A Tool for Implementing Privacy in Nano

Abstract

We present a work in progress strategy for implementing privacy in Nano at the consensus level, that can be of independent interest. Nano is a cryptocurrency that uses an Open Representative Voting (ORV) as a consensus mechanism, a variant of Delegated Proof of Stake. Each transaction on the network is voted on by representatives and each vote has a weight equal to the percentage of their total delegated balance. Every account can delegate their stake to any other account (including itself) and change it anytime it wants. The fundamental goal of this paper is to construct a tool for the consensus algorithm to function without knowing the individual balances of each account. The tool is composed of three different schemes. The first is a weighted threshold secret sharing scheme based on Shamir's secret sharing scheme, used to generate a secret amongst a set of distributed parties, which will be a private key of an additive homomorphic ElGamal cryptosystem over elliptic curves. The second is a polynomials commitment scheme used to make the previous scheme verifiable, i.e., without the need for a trusted dealer. Finally, the third scheme is used to decrypt an ElGamal ciphertext without reconstructing the private key, which, because of this, can be used multiple times.