The ISC International Journal of Information Security

Abstract The potential of Attribute-Based Encryption (ABE) in the context of IoT has driven researchers to propose pairing-free ABE schemes that are suitable for resource-constrained devices. Unfortunately, many of these schemes turned out to be insecure. This fact reinforces the view of some researchers according to which instantiating an Identity-Based Encryption (IBE) in plain Decisional Diffie-Hellman (DDH) groups is impossible. In this paper, we provide a generic Ciphertext-Policy ABE (CP-ABE) scheme supporting secret AND-gate policy using Inner-Product Functional Encryption (IPFE). We also propose an instantiation of our generic CP-ABE scheme based on the DDH assumption. From our generic CP-ABE scheme, we derive an IBE scheme by introducing the concept of Clustered Identity-Based Encryption (CIBE). Our schemes show that it is possible to construct secure IBE and ABE schemes based on the classical DDH assumption. An implementation of our CIBE in Python using the Charm framework is available on GitHub.