Expressive Data Sharing and Self-Controlled Fine-Grained Data Deletion in Cloud-Assisted IoT

Expressive data sharing and efficient data deletion are essential to drive the development of cloud-assisted IoT. But insecure transmission and the vulnerability of the cloud server may cause potential threats to IoT data, attribute-based encryption (ABE) is widely applied to ensure data confidentially. Nonetheless, the potential data exposure caused by the compromised long-term key and the contradiction between conventional access structures in ABE and the various demands of data owners are still two huge challenges. To overcome these challenges, this article designs an unbounded and puncturable ciphertext-policy ABE with arithmetic span program ( $\mathcal {UP}$ - $\mathcal {CP}$ - $\mathcal {ABE}$ - $\mathcal {ASP}$ ) scheme and presents an expressive data sharing and self-controlled fine-grained data deletion solution in cloud-assisted IoT, which allows data owners to efficiently encrypt and share data with various computable access policies, but also enables data owners and data users to independently delete specific data stored in the cloud. The designed $\mathcal {UP}$ - $\mathcal {CP}$ - $\mathcal {ABE}$ - $\mathcal {ASP}$ leverages unbounded ABE and puncturable encryption to support the flexible update of system parameters and the deletion of specific data. Also, the arithmetic span program access structure is combined to realize expressive data sharing. Moreover, the $\mathcal {UP}$ - $\mathcal {CP}$ - $\mathcal {ABE}$ - $\mathcal {ASP}$ is adaptively secure in the standard model, and comprehensive performance evaluations demonstrate its practicability and scalability in cloud-assisted IoT.