Censorship
Censorship on Transactions
Nakamoto PoW
Ghassan O. Karame (NEC Laboratories), Elli Androulaki (IBM Research), Marc Roeschlin, Arthur Gervais (ETH Zurich)
TISSEC, 2015
Privacy and accountability around double spending
Fredrik Winzer, Benjamin Herd (Robert Bosch GmbH) and Sebastian Faust (Technical University Darmstadt)
Temporary censorship against a specific account
Formalize with Markov game
Aljosha Judmayer (SBA Research), Nicholas Stifter (TU Wien), Alexei Zamyatin (Imperial College London), Itay Tsabary, Ittay Eyal (Technion and IC3), Peter Gaži (IOHK), Sarah Meiklejohn (University College London), Edgar Weippl (SBA Research)
Cost of censorship
Solution
Kfir Lev-Ari (Technion IIT), Alexander Spiegelman (VMware Research), Idit Keidar (Technion IIT), Dahlia Malkhi
OPODIS'19, Best paper award
Fairness about the ratio of transactions that each participants appends to the ledger
Assume ratitonal participants (utility function is the ratio of her included transactions)
A master decides the ratio to punish misbahaving participants
Detectable all-to-all communication primitive to detect misbehaviors in synchrony
Implementation with Hyperledger Iroha, PBFT (Castro's implementation) Yair Amir, Brian Coan, Jonathan Kirsch, John Lane
Periodically (e.g., once every 10 blocks) perform an agreement on a set of blined transactions
Each validator proposes a set of blined transactions which they think being censored
The leader is then obliged to include after the transaction are revealed, otherwise validators perform view-change
Threshold encryption of transactions
Censorship on Validators
Incentives
"Penalize both sizes"
Detection/Rejection
The suspicion score of a chain = how much the chain has been censoring validators' votes
Users are guaranteed to have suspicion scores that are reasonably similar
Help the sorcial coordination on whether or not to perform a minority fork to escape a censorship attack
Others