Designing quantum-secure attribute-based encryption

In the last couple of decades, Attribute-Based Encryption (ABE) has been a promising encryption technique to realize fine-grained access control over encrypted data. ABE has appealing functionalities such as (i) access control through encryption and (ii) encrypting a message to a group of recipients without knowing their actual identities. However, the existing state-of-the-art ABEs are based on number-theoretic hardness assumptions. These designs are not secure against attacks by quantum algorithms such as Shor algorithm. Moreover, existing Post-Quantum Cryptography (PQC)-based ABEs fail to provide long-term security. Therefore, there is a need for quantum secure ABE that can withstand quantum attacks and provides long-term security. In this work, for the first time, we introduce the notion of a quantum-secure ABE (qABE) framework that preserves the classical ABE’s functionalities and resists quantum attacks. Next, we provide a generic construction of qABE which is able to transform any existing ABE into qABE scheme. Thereafter, we illustrate a concrete construction of a quantum ABE based on our generic transformation qABE and the Waters’ ciphertext-policy ABE scheme.