A Flexible Privacy-Preserving Data Sharing Scheme in Cloud-Assisted IoT

Abstract

Cloud-assisted Internet of Things (IoT) has become an increasingly popular technological trend as the performance of IoT applications can be greatly improved by delegating the cloud to manage massive IoT data. To protect the confidentiality of data outsourced from IoT devices to the cloud, cryptographic mechanisms are usually employed to encrypt the data in such a way that only the user designated by the data owner can decrypt the data. However, in the IoT multiuser environment, the encrypted data may also need to be shared with more users beyond the initially designated one. In this article, we propose a flexible privacy-preserving data sharing (FPDS) scheme in cloud-assisted IoT. With the FPDS scheme, an IoT user can encrypt data to a recipient by using identity-based encryption. More importantly, the IoT user can specify a fine-grained access policy to generate a delegation credential, and then send this credential to the cloud so that it can convert all the encrypted data satisfying the access policy into new ciphertexts that are readable to a new recipient. In this way, IoT users can share the data outsourced to the cloud in a flexible and privacy-preserving manner. Detailed security analysis shows that the FPDS scheme is secure against semitrusted cloud and malicious IoT users. Thorough theoretical and experimental analyses demonstrate the high efficiency of the scheme.