Benoît Libert Jean-Jacques Quisquater Identity Based Undeniable Signatures. 112-125 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2964&spage=112 2004 conf/ctrsa/2004 CT-RSA db/conf/ctrsa/ctrsa2004.html#LibertQ04