ABP: Attribute-Based Broadcast Proxy Re-Encryption With Coalitional Game Theory

This article proposes attribute-based broadcast proxy (ABP) re-encryption with coalitional game theory—a scheme to share encrypted cloud data with Internet of Things (IoT) devices. The scheme reduces the decryption costs on the receiver's side. In the case of sharing data with a subgroup of IoT devices, i.e., identities, where attributes satisfy a particular access policy, and the cardinality of IoT devices satisfying the access policy is not known to the data owner, the existing encryption techniques, such as broadcast proxy re-encryption and attribute-based encryption, cannot solve the problem. Hence, we propose the concept of attribute-based encryption in broadcast proxy re-encryption, named ABP. In ABP, we use the coalitional game theory to find the optimal coalition for minimizing the decryption cost and the total cost of the system. We prove that ABP is a selective security chosen-plaintext attack secure under the random oracle model. The performance of ABP is evaluated and compared with the existing broadcast proxy re-encryption schemes. We observe that ABP reduces the decryption cost. Furthermore, the total cost of the system is reduced using the coalitional game.