Synchronized clock
Synchronous Byzantine Agreement with Expected O(1) Rounds, Expected O(n^2) Communication, and Optimal Resilience
Ittai Abraham et al.
Section 5 Clock Synchronization
Threshold Logical Clocks for Asynchronous Distributed Coordination and Consensus
July 17, 2019, WIP
Bryan Ford (EPFL)
Chain-based PoS
Ouroboros
Ouroboros Chronos: Permissionless Clock Synchronization via Proof-of-Stake
Christian Badertscher, Peter Gaˇzi, Aggelos Kiayias, Alexander Russell, and Vassilis Zikas
Slide at EuroCrypto'19 rump session
Based on Ouroboros Genesis
https://gyazo.com/c5afbdc4afd30bc7b6e3e9ef5d06213b
Ouroboros Clepsydra: Ouroboros Praos in the Universally Composable Relative Time Model
Handan Kılın¸c Alper (Web3 Foundation)
Based on Ouroboros Praos
https://gyazo.com/107d2684ff8e257fd58246089cbaa19e
Follow-up: Consensus on Clock in Universally Composable Timing Model Clock Syncronization Protocol for Full Nodes of a Blockchain
Generalization of Ouroboros Clepsydra
Comparision with Chronos
They assume that there exists a core set of parties (termed “alert parties”) who are honest and synchronized.
The existence of such a core set of parties is based on the assumption that their clocks follow almost the same rate
Chronos's synchronization algorithm helps new joining parties to synchronize themselves with the alert parties
Our model and theirs differ on this point, as we assume that the clocks of parties can arbitrarily shift
Eth2
Network-adjusted timestamps @ethresear.ch, 2018.11, Vitalik
When a node receives a message from another node, it calculates the implied timestamp of that node: for example, if genesis time is 1500000000, slot length is 8 seconds, and it receives a block with slot number 10, it takes an implied timestamp of 1500000080. A node can compute the median implied timestamp of all nodes based on their latest messages, and simply adopt it
Time attacks and security models @ethresear.ch, 2020.2, Alex Vlasov
Follow-up of Time as a Public Service in Byzantine context
#PoS