Background: The cloud storage service allows its users to easily store, manage and share
their data using large variety of devices. However, upon outsourcing their data, the users require ways
to ensure their data confidentiality without losing their granular and flexible data sharing capabilities.
Method: We propose a scheme, based on cipher-text policy attribute based encryption that uses threshold-
gate access structures as the main access structure. The proposed scheme is able to maintain data
confidentiality while providing data owners with an efficient, flexible, scalable and easily manageable
access control and efficient revocation.
Results: The Experimental results show that the usage of threshold gate access structures results in a
large increase in the efficiency of the encryption operation. Moreover, the proposed revocation process
is able to achieve both forward and backward security while maintaining a low overhead on the data
owner and the users.
Conclusion: The proposed scheme uses threshold gate access structures which increases the flexibility
of the access structure and reduces the size of linear secret sharing matrices and the computational
overhead of the encryption scheme when having complex access structures. The scheme also introduces
an efficient revocation operation that is able to achieve forward and backward security without incurring
a large computation, storage or communication overhead.