Private Proof-of-Stake Blockchains using Differentially-private Stake Distortion

Chenghong Wang; David Pujo; Kartik Nayak; Ashwin Machanavajjhala

Paper 2023/787

Private Proof-of-Stake Blockchains using Differentially-private Stake Distortion

Chenghong Wang

, Duke University

David Pujo, Duke University

Kartik Nayak, Duke University

Ashwin Machanavajjhala, Duke University

Abstract

Safety, liveness, and privacy are three critical properties for any private proof-of-stake (PoS) blockchain. However, prior work (SP'21) has shown that to obtain safety and liveness, a PoS blockchain must in theory forgo privacy. Specifically, to ensure safety and liveness, PoS blockchains elect parties based on stake proportion, potentially exposing a party's stake even with private transaction processing. In this work, we make two key contributions. First, we present the first stake inference attack applicable to both deterministic and randomized PoS with exponentially less running time in comparison with SOTA designs. Second, we use differentially private stake distortion to achieve privacy in PoS blockchains and design two stake distortion mechanisms that any PoS protocol can use. We further evaluate our proposed methods using Ethereum 2.0, a widely-recognized PoS blockchain in operation. Results demonstrate effective stake inference risk mitigation, reasonable privacy, and preservation of essential safety and liveness properties.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Preprint.
Keywords: blockchains private ledger differential privacy network attacks UC security proof-of-stake
Contact author(s): cw374 @ duke edu
david @ cs duke edu
kartik @ cs duke edu
ashwin @ cs duke edu
History: 2023-05-30: approved; 2023-05-30: received; See all versions
Short URL: https://ia.cr/2023/787
License: CC BY

BibTeX

@misc{cryptoeprint:2023/787,
      author = {Chenghong Wang and David Pujo and Kartik Nayak and Ashwin Machanavajjhala},
      title = {Private Proof-of-Stake Blockchains using Differentially-private Stake Distortion},
      howpublished = {Cryptology ePrint Archive, Paper 2023/787},
      year = {2023},
      note = {\url{https://eprint.iacr.org/2023/787}},
      url = {https://eprint.iacr.org/2023/787}
}