Further Study on Proxy Authorization and Its Scheme

Proxy authorization makes it possible to entrust the right of signing or making decisions to other parties. This paper analyzes the basic principles and security problems of proxy authorization schemes and presents three proxy authorization schemes based on elliptic curves cryptosystem. In the first multiparty proxy authorization scheme, a group of n members can cooperate to entrust their right, and the authorizing right can be supervised by secret sharing mechanism. In the second multicast proxy authorization scheme, the members can entrust their right in multicast mode. The multicasting design strategy prevents coalition attack, avoids the problem of generalized signature forgery. In the last conditionally anonymous scheme, the identity blinding algorithm enables the proxy signer to be anonymous and the anonymity can also be revoked if necessary. This design strategy avoids the misuse of proxy authorization and renders effective supervision on signature entrusting and proxy signing.