Paper 2023/642

PELTA -- Shielding Multiparty-FHE against Malicious Adversaries

Sylvain Chatel, École Polytechnique Fédérale de Lausanne
Christian Mouchet, École Polytechnique Fédérale de Lausanne
Ali Utkan Sahin, École Polytechnique Fédérale de Lausanne
Apostolos Pyrgelis, École Polytechnique Fédérale de Lausanne
Carmela Troncoso, École Polytechnique Fédérale de Lausanne
Jean-Pierre Hubaux, École Polytechnique Fédérale de Lausanne

Multiparty fully homomorphic encryption (MFHE) schemes enable multiple parties to efficiently compute functions on their sensitive data while retaining confidentiality. However, existing MFHE schemes guarantee data confidentiality and the correctness of the computation result only against honest-but-curious adversaries. In this work, we provide the first practical construction that enables the verification of MFHE operations in zero-knowledge, protecting MFHE from malicious adversaries. Our solution relies on a combination of lattice-based commitment schemes and proof systems which we adapt to support both modern FHE schemes and their implementation optimizations. We implement our construction in PELTA. Our experimental evaluation shows that PELTA is one to two orders of magnitude faster than existing techniques in the literature.

Available format(s)
Cryptographic protocols
Publication info
secure multiparty computationhomomorphic encryptionlattice-based cryptographyzero-knowledge proofs
Contact author(s)
sylvain chatel @ epfl ch
2023-05-08: revised
2023-05-05: received
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Creative Commons Attribution


      author = {Sylvain Chatel and Christian Mouchet and Ali Utkan Sahin and Apostolos Pyrgelis and Carmela Troncoso and Jean-Pierre Hubaux},
      title = {PELTA -- Shielding Multiparty-FHE against Malicious Adversaries},
      howpublished = {Cryptology ePrint Archive, Paper 2023/642},
      year = {2023},
      note = {\url{}},
      url = {}
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