An Inner Product Space-Based Hierarchical Key Assignment Scheme for Access Control

An inner product space-based hierarchical access control scheme is presented in this work. The proposed scheme can be utilized in any cloud delivery model where the data owner implements a hierarchical access control policy. In other words, the scheme adjusts any hierarchical access control policy to a digital medium. The scheme is based on inner product spaces and the method of orthogonal projection. While distributing a basis for each class by the data owner, left-to-right and bottom-up (LRBU) policy can ensure much more flexibility and efficiency, especially during any change in the structure. For each class, the secret keys can be derived only when a predetermined subspace is available. Our scheme is resistant to collusion attacks and privilege creep problems, as well as providing key recovery and key indistinguishability security. The performance analysis also shows us that the data storage overhead is much more tolerable than other schemes in the literature. In addition, the other advantage of our key access scheme over many others in the literature is that it requires only one operation to derive the secret key of child classes securely and efficiently.