Paper 2022/1435

Eagle: Efficient Privacy Preserving Smart Contracts

Carsten Baum, Technical University of Denmark
James Hsin-yu Chiang, Technical University of Denmark
Bernardo David, IT University of Copenhagen
Tore Kasper Frederiksen, Alexandria Institute, Denmark

The proliferation of Decentralised Finance (DeFi) and Decentralised Autonomous Organisations (DAO), which in current form are exposed to front-running of token transactions and proposal voting, demonstrate the need to shield user inputs and internal state from the parties executing smart contracts. In this work we present “Eagle”, an efficient UC-secure protocol which efficiently realises a notion of privacy preserving smart contracts where both the amounts of tokens and the auxiliary data given as input to a contract are kept private from all parties but the one providing the input. Prior proposals realizing privacy preserving smart contracts on public, permissionless blockchains generally offer a limited contract functionality or require a trusted third party to manage private inputs and state. We achieve our results through a combination of secure multi-party computation (MPC) and zero-knowledge proofs on Pedersen commitments. Although other approaches leverage MPC in this setting, these incur impractical computational overheads by requiring the computation of cryptographic primitives within MPC. Our solution achieves security without the need of any cryptographic primitives to be computed inside the MPC instance and only require a constant amount of exponentiations per client input.

Note: Under submission.

Available format(s)
Cryptographic protocols
Publication info
secure multi-party computation confidential ledger smart contracts blockchain
Contact author(s)
cabau @ dtu dk
jchi @ dtu dk
bernardo @ bmdavid com
tore frederiksen @ alexandra dk
2022-10-24: approved
2022-10-21: received
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      author = {Carsten Baum and James Hsin-yu Chiang and Bernardo David and Tore Kasper Frederiksen},
      title = {Eagle: Efficient Privacy Preserving Smart Contracts},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1435},
      year = {2022},
      note = {\url{}},
      url = {}
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