| Popis: |
In order to overcome the drawbacks of current attribute-based signature (ABS) schemes in terms of security,efficiency and signing policy,Ma,et al.and Cao,et al.respectively proposed a threshold ABS with single attribute au-thority and a multi-authority ABS with signing policy supporting AND,OR,threshold gates,and presented the security proof of their schemes under computational Diffie-Hellman assumption.Both schemes were demonstrated have security pitfalls by presenting specified attacks against them.Specifically,their schemes are all vulnerable to forgery attack.Thus,they are not feasible for practical applications.In addition,the cause of the flaws in these ABS schemes are presented,as well as an improvement of Ma et al.'s scheme. |
