Abstract

Owing to the large volume of data, decentralized key management schemes are preferred over centralized ones. Often encryption and decryption are quite expensive and not practical when user access data from resource constrained devices. We propose a decentralized ABE scheme. Most of the existing Decentralized ABE scheme suffer from this disadvantage of expensive computational cost and weak security. In this paper we present a novel secure Online/offline Decentralized Attribute Based Encryption for Mobile Clouds. The proposed scheme reduces the online computation burden for data owners by completing the preprocessing computation as much as during the offline phase. The proposed scheme eliminates a major of computation overhead on user side by migrating the partial decryption computation to the cloud servers. In order to guarantee data security, a hash function is utilized to verify the integrity. Divide the encryption into two phases, offline pre-processing phase which is done when the device is otherwise not in use. For decryption outsourcing, data users need to generate a transformed version of the decryption key allowing an untrusted proxy server to partially decrypt the ciphertext. Data users can then fully decrypt the partially decrypted ciphertext. User revocation in this scheme without incurring additional cost in the online phase.

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