Paper 2023/362

Protecting Quantum Procrastinators with Signature Lifting: A Case Study in Cryptocurrencies

Or Sattath, Computer Science Department, Ben-Gurion University of the Negev
Shai Wyborski, School of Computer Science and Engineering, The Hebrew University of Jerusalem, Computer Science Department, Ben-Gurion University of the Negev

Current solutions to quantum vulnerabilities of widely used cryptographic schemes involve migrating users to post-quantum schemes before quantum attacks become feasible. This work deals with protecting quantum procrastinators: users that failed to migrate to post-quantum cryptography in time. To address this problem in the context of digital signatures, we introduce a technique called signature lifting, that allows us to lift a deployed pre-quantum signature scheme satisfying a certain property to a post-quantum signature scheme that uses the same keys. Informally, the said property is that a post-quantum one-way function is used "somewhere along the way" to derive the public-key from the secret-key. Our constructions of signature lifting relies heavily on the post-quantum digital signature scheme Picnic (Chase et al., CCS'17). Our main case-study is cryptocurrencies, where this property holds in two scenarios: when the public-key is generated via a key-derivation function or when the public-key hash is posted instead of the public-key itself. We propose a modification, based on signature lifting, that can be applied in many cryptocurrencies for securely spending pre-quantum coins in presence of quantum adversaries. Our construction improves upon existing constructions in two major ways: it is not limited to pre-quantum coins whose ECDSA public-key has been kept secret (and in particular, it handles all coins that are stored in addresses generated by HD wallets), and it does not require access to post-quantum coins or using side payments to pay for posting the transaction.

Available format(s)
Publication info
BitcoinCryptocurrenciesPost-quantum CryptographyProcrastinatorsPicnic
Contact author(s)
sattath @ bgu ac il
shai wyborski @ mail huji ac il
2023-03-16: approved
2023-03-12: received
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Creative Commons Attribution-NonCommercial-NoDerivs


      author = {Or Sattath and Shai Wyborski},
      title = {Protecting Quantum Procrastinators with Signature Lifting: A Case Study in Cryptocurrencies},
      howpublished = {Cryptology ePrint Archive, Paper 2023/362},
      year = {2023},
      note = {\url{}},
      url = {}
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