@nic__carter 1/ The paper, "Formal Barriers to Longest-Chain Proof-of-Stake Protocols" by Jonah Brown-Cohen, Arvind Narayanan, Christos-Alexandros Psomas, and S. Matthew Weinberg assumes PoS blockchains are "similar" to PoW, except for wasted energy associated with the latter.
@nic__carter 2/ In other words, they assume PoS blockchains that are leader-based, similar to PoW's method of choosing the winning miner to add the new block to the blockchain.
3/They also assume PoS blockchains use the "longest chain rule," similar to PoW.
3/They also assume PoS blockchains use the "longest chain rule," similar to PoW.
@nic__carter 4/ With these assumptions the aim is to isolate the incentive-driven threat.
5/ Blockchain designs that are not leader-based or that do not use the "longest chain rule" don't fall into the same threat model.
5/ Blockchain designs that are not leader-based or that do not use the "longest chain rule" don't fall into the same threat model.
@nic__carter 6/ @storecoin's BlockFin consensus engine is leaderless -- there is no leader or delegate chosen to create new blocks. The consensus engine requires that all nodes validate and sign the blocks.
7/ For their participation, all validators share the block reward for every block.
7/ For their participation, all validators share the block reward for every block.
@nic__carter @storecoin 8/ This equitable incentive model ensures there is no $ benefit in deviating from the protocol.
9/ This leaderless consensus eliminates any long-term tendency toward centralization. By addressing the centralization concerns in the design, BlockFin ensures true decentralization.
9/ This leaderless consensus eliminates any long-term tendency toward centralization. By addressing the centralization concerns in the design, BlockFin ensures true decentralization.
@nic__carter @storecoin 10/ In @storecoin's BlockFin BFT consensus algorithm, the incoming transactions are assembled into pre-created blocks that are later validated and signed by all validators.
11/ This avoids chain forks, so the longest chain rule doesn't apply.
11/ This avoids chain forks, so the longest chain rule doesn't apply.
@nic__carter @storecoin 12/ Together, these two properties discourage temptations to deviate from the protocol rules.
13/ So, what could go wrong with such a design?!
🤔
13/ So, what could go wrong with such a design?!
🤔
@nic__carter @storecoin 14/ Block validation progress requires > 2/3 of validators to sign the blocks, so malicious validators may delay signing the blocks by going offline for extended periods of time.
@nic__carter @storecoin 15/ But, unless > 1/3 of validators collude and coordinate their attack, the block validation progresses well. The way BlockFin validation is designed, the whole network and any external observers know who is not signing the blocks.
@nic__carter @storecoin 16/ This is because the assembled blocks are in pending state with ~2/3 validator signatures, so all observers know the current state of block validation progress. BlockFin addresses this concern in a novel way, but that discussion is for another day!
@nic__carter @storecoin 17/ We believe that PoS blockchains can't be simple replicas of PoW blockchains, sans mining. The goal of PoS is not just to save wasted energy associated with PoW.
@nic__carter @storecoin 17/ Decentralization (security) can't be achieved with technology alone. We believe that economics and on-chain governance must bear equal responsibilities. @storecoin's Dynamic Proof-of-Stake protocol, which uses BlockFin as its "technology" foundation, will try to achieve this. 
