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b'Aparna Krishnan is head of education at Blockchain at Berkeley and co-founder of Mechanism Labs, an open source blockchain research lab. Earlier this year, Aparna was awarded a scholarship by the DFINITY Foundation for Mechanism Labs\\u2019 research into consensus mechanisms. This episode is essentially a primer for advanced discussion of consensus in decentralized networks.\\n\\nhttps://mechanismlabs.io/\\nhttps://github.com/aparnakr\\nhttps://twitter.com/aparnalocked\\nhttps://medium.com/@aparnalocked\\n\\nAparna Krishnan\\nCo-founder mechanism labs open source research lab\\nAll work and research is on Github\\nTelegram: @mechanism_labs\\nCo-founder of the education team at Blockchain Berkeley\\nConsensus researcher\\nTeaches executive education courses\\n\\nConsensus\\nProof of Work\\nProof of Stake\\nOld Field\\n\\nHistory\\nCynthia Dwork developed stronger adversarial models\\nDid not have many applications\\nBlockchain has brought cryptography and consensus into the mainstream eye\\n\\n\\n\\nProtocols\\nDFINITY\\nTendermint\\nBitcoin\\nFocus has been on proof of stake protocols\\nMining may not be sustainable\\nLong term sustainabilities and lack of externalities is important\\nProof of stake offers efficiently\\nAs does proof of elapsed time and proof of space and time\\n\\nConsensus\\nSybil control\\nComing to agreement relies on traditional consensus\\nPoS, PoW refer to the sybil control mechanism\\nPoS - Putting down capital\\nFinancial penalty for misbehavior\\nToken holders are participants\\nPoW - burning energy\\nOne cpu, one vote\\nNo connection between token custody and rewards\\nP o Elapsed Time \\nProof of Authority placing reputation\\nA cost of playing ball\\nTraditional Consensus (PBFT)\\nNo concept of probabilistic finality\\nAll honest nodes come to final agreement\\nClosed, permissioned\\nBlockchain\\nAll nodes may with a high degree of probability agree\\nA probabilistic guarantee\\n\\nLongest Chain Rule\\nLongest sequence of blocks is the \\nEthereum\\nGhost\\nCan be attacked by a stealthy entity\\nOpen, permissionless, decentralized\\nInefficient\\nNode churn\\nBetter liveness properties\\n\\nEarly PoS 2013\\nPeerCoin\\nNXT\\nBitshares\\nPrimitive\\nState grinding attack vulnerable\\nRandomness derived from blockhashes\\n\\nNew Generation\\nDFINITY\\nUses threshold relay decentralized randomness\\nTendermint\\nRound robin\\nHas social layer fallback\\nEthereum Casper\\nThunderella\\nAlgorand\\nHides the block creator until the block has been created\\n\\nIn Tendermint a minority below the assumption cannot break finality\\nIn Bitcoin >10% can change the finality through threatening to censor \\n\\nHard to get both economic and cryptographic security. Not clear that bribing and collusion attacks have been solved. No protocols have shown sophisticated economic models.\\n\\nMechanism Labs\\nFocussing on incentive schemes\\nWhat does it mean to have a stable, scalable protocol\\nScalability\\n\\nProof of Replication\\nRecent work with Verifiable delay functions\\nIn commit/reveal schemes there is an opportunity to manipulate by giving only one person the ability to reveal the randomness\\nVerifiable delay functions allow anyone to reveal the randomness\\nASIC resistance because not parallelizable'