Mihir Bellare Haixia Shi Chong Zhang Foundations of Group Signatures: The Case of Dynamic Groups. 136-153 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3376&spage=136 2005 conf/ctrsa/2005 CT-RSA db/conf/ctrsa/ctrsa2005.html#BellareSZ05