Paper 2023/832

Unstoppable Wallets: Chain-assisted Threshold ECDSA and its Applications

Guy Zyskind, Massachusetts Institute of Technology, SCRT Labs
Avishay Yanai
Alex "Sandy" Pentland, Massachusetts Institute of Technology

The security and usability of cryptocurrencies and other blockchain-based applications depend on the secure management of cryptographic keys. However, current approaches for managing these keys often rely on third parties, trusted to be available at a minimum, and even serve as custodians in some solutions, creating single points of failure and limiting the ability of users to fully control their own assets. In this work, we introduce the concept of unstoppable wallets, which are programmable threshold ECDSA wallets that allow users to co-sign transactions with a confidential smart contract, rather than a singular third-party. We propose a new model that encapsulates the use of a confidential smart contract as both a party and the sole (broadcast) communication channel in secure Multi-Party Computation (MPC) protocols. We construct highly efficient threshold ECDSA protocols that form the basis of unstoppable wallets and prove their security under this model, achieving the standard notion of fairness and robustness even in case of a dishonest majority of signers. Our protocols minimize the write-complexity for threshold ECDSA key-generation and signing, while reducing communication and computation overhead. We implement these protocols as smart contracts, deploy them on Secret Network, and showcase their applicability for two interesting applications, policy checking and wallet exchange, as well as their efficiency by demonstrating low gas costs and fees.

Available format(s)
Cryptographic protocols
Publication info
threshold cryptographyMPCBlockchainsignaturesrobustnessfairness
Contact author(s)
guyz @ mit edu
ay yanay @ gmail com
pentland @ mit edu
2023-06-06: approved
2023-06-05: received
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Creative Commons Attribution


      author = {Guy Zyskind and Avishay Yanai and Alex "Sandy" Pentland},
      title = {Unstoppable Wallets: Chain-assisted Threshold ECDSA and its Applications},
      howpublished = {Cryptology ePrint Archive, Paper 2023/832},
      year = {2023},
      note = {\url{}},
      url = {}
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