Byoungcheon Lee Kim-Kwang Raymond Choo Jeongmo Yang Seungjae Yoo Secret Signatures: How to Achieve Business Privacy Efficiently? 30-47 2007 conf/wisa/2007 WISA http://dx.doi.org/10.1007/978-3-540-77535-5_3 db/conf/wisa/wisa2007.html#LeeCYY07