擁有撤銷機制的前進式群體簽章系統

Abstract

群體簽章系統允許群體中任何的成員，以匿名性和無連結性的方式，以此群體的身份去作簽名。在有爭議時，只有群體管理者有能力去公開簽名者的身份。當一個群體的成員因為某些原因如調職或被公司開除而離開的時候，群體管理者必須要執行某種機制來廢止這個成員代替群體簽名的能力。 在這篇論文中，我們考慮在一個群體中廢止成員代替群體簽名能力的問題，提出一個簡單的廢止（撤銷）機制。而我們的群體簽章系統擁有較短的群體簽章大小及較快速的簽名程序。在強RSA假設和DDH假設之下，我們也證明提出的群體簽章系統及廢止機制是安全的。

A group signature scheme allows any group member to sign on behalf of the group in an anonymous and unlinkable way. In case of dispute, only the group manager has ability to open the identity of a group member. When a member of the group leaves for some reasons such as promotion in position or being fired by his company, the group manager should take some action to revoke this member. In this thesis, we consider the problem of revocation in a group signature scheme and propose a simple revocation mechanism. Our group signature scheme has shorter signature size and a faster signing procedure. We also prove that our group signature scheme and revocation mechanism are secure under the strong RSA assumption and the DDH assumption.