User Collusion Avoidance Scheme for Privacy-Preserving Decentralized Key-Policy Attribute-Based Encryption -- Full Version
This addresses data confidentiality and privacy issues for users in untrusted cloud environments, representing an incremental improvement over prior methods.
The paper tackles the problem of user collusion in decentralized key-policy attribute-based encryption for cloud data sharing, proposing a scheme that preserves user privacy and mitigates this vulnerability, with security based on the decisional bilinear Diffie-Hellman assumption instead of nonstandard ones.
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.