| Summary: | 碩士 === 逢甲大學 === 資訊工程所 === 90 ===
Since Mambo, Usuda and Okamoto introduced the proxy signature scheme, many variant schemes have been proposed to achieve the varied specific requirements in a proxy signature situation. A (t, n) threshold proxy signature scheme is a signature that t or more proxy signers of assigned group of n proxy signers sign a message on behalf of an original signer. In the thesis, we will propose some disadvantages and weaknesses of the previous threshold proxy signature schemes. Furthermore, we propose a new threshold proxy signature scheme to overcome the weaknesses of the previous schemes and preserve all the advantages of the previous scheme.
In addition, with the rapid development of computer technologies, people store a great deal of information in the computer systems. Recently, the major development of computer network is storing various resources in distributed computer systems, so that these resources may be shared through the network in the form of network services provided by servers. Therefore, it is necessary to do user authentication that is identification and verification and grant access right for resource protection in a distributed computer network. In the thesis, we use the concept of delegation to provide a new solution. It is proposed here allowing servers to simplify verification processes for a user with multiple access requests at the same time and users to update their access rights dynamically.
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