Paper 2022/1673

DeV-IP: A k-out-n Decentralized and verifiable BFV for Inner Product evaluation

Jose Contreras, Humanode
Hardik Gajera, Humanode

The biometric system has become the desired alternative to a knowledge-based authentication system. An authentication system does not provide uniqueness, as a single user can create multiple registrations with different identities for authentication. Biometric authentication identifies users based on physical traits (fingerprint, iris, face, voice), which allows the system to detect multiple authentications from the same user. The biometric templates must be encrypted or hidden to preserve users' privacy. Moreover, we need a system to perform the matching process over encrypted data without decrypting templates to preserve the users' privacy. For the euclidean distance-based matching process, centralized server-based authentication leads to possible privacy violations of biometric templates since the power of computing inner product value over any two encrypted templates allows the server to retrieve the plain biometric template by computing a few inner products. To prevent this, we considered a decentralized system called collective authority, which is a part of a public network. The collective authority computes the collective public key with contributions from all nodes in the collective authority. It also performs a matching process over encrypted biometric templates in a decentralized manner where each node performs partial matching. Then the leader of the collective authority combines it to get the final value. We further provide a lattice-based verification system for each operation. Every time a node performs some computations, it needs to provide proof of the correctness of the computation, which is publicly verifiable. We finally make the system dynamics using Shamir's secret sharing scheme. In dynamic collective authority, only $k$ nodes out of the total $n$ nodes are required to perform the matching process. We further show that the security of the proposed system relies on the security of the underlying encryption scheme and the secret sharing scheme.

Available format(s)
Public-key cryptography
Publication info
Lattice-based Encryption Verification Shamir's secret-sharing Homomorphic Encryption Collective Authority
Contact author(s)
tanogedler @ humanode io
hgajera @ humanode io
2022-12-02: approved
2022-12-01: received
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Creative Commons Attribution


      author = {Jose Contreras and Hardik Gajera},
      title = {{DeV}-{IP}: A k-out-n Decentralized and verifiable {BFV} for Inner Product evaluation},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1673},
      year = {2022},
      note = {\url{}},
      url = {}
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