具有向后无关性的本地验证撤销群签名方案

A New Verifier-Local Revocation Group Signature with Backward Unlinkability

用户撤销是群签名中的一个重要问题,本地验证撤销(VLR)是一种有效的解决方法.2004年CCS的Boneh-Shacham方案是签名长度很短的VLR方案,但它不具有向后无关性(BU).此后BU-VLR群签名方案被提出来,效率却弱于Boneh-Shacham方案.基于弱DTDH假设和q-SDH假设,首先提出一种BU-VLR群签名方案,具有较短的签名长度和较低的运算量.其次为了减少公布在撤销列表上的数据,给出扩展方案.最后用构造签名的方法,改进2007年IEICE中Nakanishi-Funabiki方案,使得到的签名长度更短,运算量保持不变.

Membership revocation is an important issue of group signatures. Verifier-local revocation （VLR for short） and witness-based method are two current main nontrivial approaches. The latter is more suitable in some environments, especially in mobile environments. In CCS＇04, an efficient VLR group signature scheme is proposed by Boneh and Shacham, which is very short but not having the propriety of backward unlinkability （BU）, a property that keeps the anonymity of a member even after he/she has been revoked. Recently, BU-VLR group signature schemes have been proposed. However, these schemes are not comparable with Boneh-Shacham＇s in performance. Based on the weak DTDH and q-SDH assumptions, a new BU-VLR group signature scheme is proposed. The advantage of the proposal is shorter signature length and lower computation cost over the previous BU-VLR group signature schemes. To reduce the data published in the revocation list, an extended version is also provided with lower overhead in computation according to the method put forward by Nakanishi and Funabiki in ASIACRYPT＇05. Finally, an improved version of the scheme in IEICE＇07 proposed by Nakanish and Funabiki is given using the construction trick in signature, the signature length of which is only 77.8% that of the original scheme under the same computation.