User Collusion Avoidance Scheme for Privacy-Preserving Decentralized Key-Policy Attribute-Based Encryption -- Full Version

TL;DR

This paper introduces a privacy-preserving decentralized key-policy attribute-based encryption scheme that prevents user collusion and maintains user privacy in distributed cloud environments, relying on standard cryptographic assumptions.

Contribution

It presents a novel decentralized attribute-based encryption scheme that mitigates user collusion and preserves privacy, using standard cryptographic assumptions unlike previous schemes.

Findings

Scheme prevents user collusion effectively.

Scheme maintains user privacy during key interactions.

Relies on standard decisional bilinear Diffie-Hellman assumption.

Abstract

Recent trend towards cloud computing paradigm, smart devices and 4G wireless technologies has enabled seamless data sharing among users. Cloud computing environment is distributed and untrusted, hence data owners have to encrypt their data to enforce data confidentiality. The data confidentiality in a distributed environment can be achieved by using attribute-based encryption technique. Decentralized attribute-based encryption technique is a variant of multiple authority based attribute-based encryption whereby any attribute authority can independently join and leave the system without collaborating with the existing attribute authorities. In this paper, we propose a privacy-preserving decentralized key-policy attribute-based encryption scheme. The scheme preserves the user privacy when users interact with multiple authorities to obtain decryption keys while mitigating the well-known user collusion security vulnerability. We showed that our scheme relies on decisional bilinear Diffie-Hellman standard complexity assumption in contrast to the previous nonstandard complexity assumptions such as $q-$decisional Diffie-Hellman inversion.