Paper 2024/705

Large-Scale MPC: Scaling Private Iris Code Uniqueness Checks to Millions of Users

Remco Bloemen, Worldcoin Foundation
Daniel Kales, TACEO
Philipp Sippl, Worldcoin Foundation
Roman Walch, TACEO

In this work we tackle privacy concerns in biometric verification systems that typically require server-side processing of sensitive data (e.g., fingerprints and Iris Codes). Concretely, we design a solution that allows us to query whether a given Iris Code is similar to one contained in a given database, while all queries and datasets are being protected using secure multiparty computation (MPC). Addressing the substantial performance demands of operational systems like World ID and aid distributions by the Red Cross, we propose new protocols to improve performance by more than three orders of magnitude compared to the recent state-of-the-art system Janus (S&P 24). Our final protocol can achieve a throughput of over a million Iris Code comparisons per second on a single CPU core, while protecting the privacy of both the query and database Iris Codes. We additionally investigate GPU acceleration for some building blocks of our protocol, which results in further speedups of over 38x compared to the respective multi-threaded CPU implementation.

Available format(s)
Cryptographic protocols
Publication info
MPCIris CodesuniquenessprivacyWorld ID
Contact author(s)
remco @ worldcoin org
kales @ taceo io
philipp @ worldcoin org
walch @ taceo io
2024-05-10: approved
2024-05-07: received
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Creative Commons Attribution


      author = {Remco Bloemen and Daniel Kales and Philipp Sippl and Roman Walch},
      title = {Large-Scale {MPC}: Scaling Private Iris Code Uniqueness Checks to Millions of Users},
      howpublished = {Cryptology ePrint Archive, Paper 2024/705},
      year = {2024},
      note = {\url{}},
      url = {}
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