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Abstract
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The transition of cryptographic primitives to the post-quantum era necessitates the rigorous translation of asymptotic security proofs into concrete parameter instantiations. This
paper evaluates the practical realizability of the Decentralized Multi-Authority AttributeBased Encryption (MA-ABE) scheme by Datta, Komargodski, and Waters (Eurocrypt 2021),
a seminal construction relying exclusively on the Learning With Errors (LWE) assumption.
While DKW21 eliminates the reliance on bilinear maps, offering resilience against quantum adversaries, our comprehensive numerical audit reveals a profound dichotomy between
its theoretical soundness and practical feasibility. We demonstrate that the convergence
of constraints derived from LWE hardness and the noise flooding technique required for
simulation-based security forces the modulus-to-noise ratio into a super-polynomial regime.
Consequently, the requisite parameters—particularly the smudging bound Bˆ—scale astronomically (≈ 1047), rendering the scheme unimplementable on existing computational substrates. Beyond identifying this ”Parameter Wall,” this work proposes a radical architectural
reconfiguration to bridge the gap between theory and practice. We introduce novel optimization strategies including the transition to non-commutative Module-LWE structures, the
invention of Coset-Restricted Lattice Hashing to minimize pre-image norms, and the adoption of Entropic Smudging via Lossy Trapdoors. Furthermore, we explore Isospectral Lattice
Deformations and Learning With Rounding (LWR) transformations to decouple security constraints from decryption correctness, outlining a viable roadmap for practical post-quantum
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