Paper 2026/1018

Symmetric Attribute-Based Encryption from Minimal Hardness Assumptions

Abstract

We present a novel construction that applies the Ciphertext-Policy Attribute-Based Encryption paradigm in an original symmetric framework, where also the encryptor needs to have enough attributes to be able to produce a ciphertext for a given policy. The scheme is built from minimal assumptions on collision-resistant hash functions and pseudorandom functions, exploiting the properties of linear secret sharing and polynomial interpolation. Thus, it is natively Post-Quantum secure. We formally define a novel extended form for access trees, that trades a polynomial space expansion for a more predictable topological structure. This structure enhance the arithmetic possibilities of the associated secret sharing primitive. Moreover, we propose a comprehensive notation for access trees, sharing and interpolation, which may help in the study of these powerful primitives.