Revisiting Module Lattice-based Homomorphic Encryption and Application to Secure-MPC
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Abstract
Homomorphic encryption (HE) schemes have gained significant popularity in modern privacy-preserving applications across various domains. While research on HE constructions based on learning with errors (LWE) and ring-LWE has received major attention from both cryptographers and software-hardware designers alike, their module-LWE-based counterpart has remained comparatively under-explored in the literature. A recent work provides a module-LWE-based instantiation (MLWE-HE) of the Cheon-Kim-Kim-Song (CKKS) scheme and showcases several of its advantages such as parameter flexibility and improved parallelism. However, a primary limitation of this construction is the quadratic growth in the size of the relinearization keys. Our contribution is two-pronged: first, we present a new relinearization key-generation technique that addresses the issue of quadratic key size expansion by reducing it to linear growth. Second, we extend the application of MLWE-HE in a multi-group homomorphic encryption (MGHE) framework, thereby generalizing the favorable properties of the single-keyed HE to a multi-keyed setting as well as investigating additional flexibility attributes of the MGHE framework.
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Anisha Mukherjee and Sujoy Sinha Roy, Revisiting Module Lattice-based Homomorphic Encryption and Application to Secure-MPC. IACR Communications in Cryptology, vol. 2, no. 2, Jul 07, 2025, doi: 10.62056/ay7qjp10.
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