Paper 2022/1513

Player-Replaceability and Forensic Support are Two Sides of the Same (Crypto) Coin

Peiyao Sheng, University of Illinois Urbana-Champaign
Gerui Wang, University of Illinois Urbana-Champaign
Kartik Nayak, Duke University
Sreeram Kannan, University of Washington
Pramod Viswanath, Princeton University

Player-replaceability is a property of a blockchain protocol that ensures every step of the protocol is executed by an unpredictably random (small) set of players; this guarantees security against a fully adaptive adversary and is a crucial property in building permissionless blockchains. Forensic Support is a property of a blockchain protocol that provides the ability, with cryptographic integrity, to identify malicious parties when there is a safety violation; this provides the ability to enforce punishments for adversarial behavior and is a crucial component of incentive mechanism designs for blockchains. Player-replaceability and strong forensic support are both desirable properties, yet, none of the existing blockchain protocols have both properties. Our main result is to construct a new BFT protocol that is player-replaceable and has maximum forensic support. The key invention is the notion of a ``transition certificate'', without which we show that natural adaptations of extant BFT and longest chain protocols do not lead to the desired goal of simultaneous player-replaceability and forensic support.

Available format(s)
Cryptographic protocols
Publication info
Player replaceability BFT Protocols Blockchain Forensics
Contact author(s)
peiyaosheng @ gmail com
geruiw2 @ illinois edu
kartik @ cs duke edu
ksreeram @ ece uw edu
pramodv @ princeton edu
2022-11-07: approved
2022-11-02: received
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      author = {Peiyao Sheng and Gerui Wang and Kartik Nayak and Sreeram Kannan and Pramod Viswanath},
      title = {Player-Replaceability and Forensic Support are Two Sides of the Same (Crypto) Coin},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1513},
      year = {2022},
      note = {\url{}},
      url = {}
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