Ethereum consensus was inspired by the choice of the greedily heaviest

Ethereum consensus was inspired by the choice of the

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Ethereum consensus was inspired by the choice of the greedily heaviest observable subtree (GHOST) State Bi,Pi the local blockchain view Each peer of the blockchain executes: Receive blocks Bj, Pj from j Bi = Bi Bj Pi = Pi Pj num-desc(b): if children(b) = then return 1 else return 1 + ∑ c children(b) num-desc(c) Prune lightest branches at i b = genesis-block(Bi) while b.next ≠ block = argmax c children(b) {num-desc (c)} B = B {block} P = P { block,b } b = block Bi,Pi = B,P [SZ15] Y. Sompolinsky and A. Zohar, “Secure high-rate transaction processing in bitcoin,” in Financial Cryptography and Data Security FC’15, 2015, pp. 507–527. 58
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Bitcoin vs. Ethereum/GHOST 59
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Ethereum branch selection 60 Ethereum codebase evolved dramatically over the past two years While originally stated as inspired by GHOST, Ethereum’s branch selection algorithm is currently different: Ethereum selects the branch with the highest total difficulty, which is the sum of the difficulties of all the cryptopuzzles of its last block and its ancestors.
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Quiz
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Question 1 62 What is the PoW mechanism useful for?
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Question 1 63 What is the PoW mechanism useful for? What is its major drawback?
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Question 2 64 What are the blocks of the branch selected by Bitcoin?
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Question 2 65 What are the blocks of the branch selected by Bitcoin? What are the blocks of the branch selected by the GHOST protocol?
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Conclusions
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Conclusions 67 Classic blockchains rely on proof-of-work to select the processes that can propose new blocks: If a process solves the cryptopuzzle, it can propose a block Else, it is not allowed, absence of PoW in a block => block ignored The consensus they use is basic: It assumes synchrony: wait to get all messages sent at t, Presume you receive all the info generated at t, and decide Let’s relax synchrony and find a solution that works even after unexpected delays
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