[Cryptography] Cryptocurrency voting games

[Sanjay Bhattacherjee]

Hello,

We have just completed a draft paper titled "Cryptocurrency voting
games". We think this work should be of interest to practitioners in
the cryptocurrency ecosystem. The abstract for the work is given
below. As a first attempt on modelling the voting game scenarios in
proof-of-work based cryptocurrencies, we are eager to have comments on
the work.
Link to the draft: https://eprint.iacr.org/2017/1167

We define a notion of stability for the cryptocurrency system based on
the number of mining pools (not necessarily the largest ones) that
should collude to attain 51% hashpower. Given a snapshot of the
hashpower distribution, the various stability statistics provide
deeper insight into different ways the system can be vulnerable from
collusions at that point. We think this will be a useful tool for
better analysis of the system that should be done regularly.

The voting game occurring in the context of the cryptocurrency
improvement proposals (BIP, EIP, etc.) leads to assigning a relevant
voting power based on a miner's (or pool's) capability to stop a
lock-in of the proposal. Given that these proposals give rise to
serious debates, a statistic for a miner's influence on the activation
of the proposals should be a good tool as well for reading the
ecosystem.

Eagerly awaiting your comments.

Regards,
Sanjay Bhattacherjee
Turing Lab, ISI Kolkata

Abstract: This work shows that weighted majority voting games occur in
cryptocurrencies. In particular, two such games are highlighted. The
first game, which we call the Rule Game, pertains to the scenario
where the entities in the system engage in a voting procedure to
accept or reject a change of rules. The second game, which we call the
Attack Game, refers to the scenario where a group of entities in a
cryptocurrency system can form a coalition to engage in double
spending. For the Rule Game we provide analysis to argue that the
Coleman’s preventive power measure is the appropriate tool for
measuring a player’s influence in the game while for the Attack Game,
we define a notion of stability based on the notion of minimal winning
coalitions. For both the Rule Game and the Attack Game, we show how to
analyse the games based on a snapshot of real world data for Bitcoin
which is presently the most popular of all the cryptocurrencies.