Paper 2021/727

SoK: Privacy-Preserving Computing in the Blockchain Era

Ghada Almashaqbeh and Ravital Solomon


Privacy is a huge concern for cryptocurrencies and blockchains as most of these systems log everything in the clear. This has resulted in several academic and industrial initiatives to address privacy. Starting with the UTXO model of Bitcoin, initial works brought confidentiality and anonymity to payments. Recent works have expanded to support more generalized forms of private computation. Such solutions tend to be highly involved as they rely on advanced cryptographic primitives and creative techniques to handle issues related to dealing with private records (e.g. concurrency and double spending). This situation makes it hard to comprehend the current state-of-the-art, much less build on top of it. To address these challenges, we develop a systematization of knowledge for privacy-preserving solutions in blockchain. To the best of our knowledge, our work is the first of its kind. After motivating design challenges, we devise two systematization frameworks---the first as a stepping stone to the second---and use them to study the state-of-the-art. For our first framework, we study the zero-knowledge proof systems used in surveyed solutions, based on their key features and limitations. Our second is for blockchain privacy-preserving solutions; we define several dimensions to categorize the surveyed schemes and, in doing so, identify two major paradigms employed to achieve private computation. We go on to provide insights to guide solutions' adoption and development. Finally, we touch upon challenges related to limited functionality, practicality, and accommodating new developments.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Minor revision. IEEE Euro S&P 2022
Blockchainsprivate paymentsprivacy-preserving computingsmart contractszero knowledge proofshomomorphic encryption
Contact author(s)
ghada @ uconn edu
ravital @ sunscreen tech
2022-03-09: last of 2 revisions
2021-06-02: received
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      author = {Ghada Almashaqbeh and Ravital Solomon},
      title = {{SoK}: Privacy-Preserving Computing in the Blockchain Era},
      howpublished = {Cryptology ePrint Archive, Paper 2021/727},
      year = {2021},
      note = {\url{}},
      url = {}
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