Revocable and time-based secure file hierarchy sharing in cloud-assisted internet of things

Cloud-assisted Internet of Things (IoT) has been widely accepted for IoT data sharing and outsourcing but owners lose control of their data. Hence, Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is proposed with fine-grained access control for encrypted data. However, a real-world situation exists in which the cloud in the existing schemes may be malicious and with not unlimited resources while data users may access the shared data based on time factor and leave the system dynamically, which can easily lead to data breach leakage, storage exhaustion and privilege confusion. Data auditing, storage saving, user revocation and time-based access control may be a feasible solution to the situation. Therefore, a revocable and time-based file hierarchy CP-ABE scheme is proposed to support user revocation, time-based access control and auditing over hierarchical data, which offers data storage saving and breach detection with efficient access control over dynamic users with time-based sharing requirements. The formal security analysis is presented. Extensive evaluations demonstrate that the proposed scheme improves encryption and decryption time by more than $$30%$$ 30 % and $$50%$$ 50 % respectively, while its storage saving gains exceeding $$50%$$ 50 % , confirming its effectiveness and efficiency in complex IoT data sharing scenario.