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An ID-based Hierarchical Access Control Scheme with Constant Size Public Parameter

Many ways are proposed to reduce the secret storage space of access control in hierarchy, but no one optimizes the public parameters which are only modified by CA. Length of each public parameter is one important factor for the size and utilization of storage space. The frequent changes on the maximum length of public parameter will be a weakness for stability, in dynamic key management. Number and length of changed public parameter are considered for the interaction between CA and trusted public platform in dynamic management. The paper proposes an improved scheme to optimize storage space of public parameter for each class from variable linear size to a small constant size. Our scheme has higher utilization, stability and efficiency on storage space of trusted public platform and needs less interaction between CA and trusted public platform. The security of this improved scheme is proved on key recovery model.