Yunlei Zhao Chan H. Lee Yiming Zhao Hong Zhu Some Observations on Zap and Its Applications. 180-193 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3089&spage=180 2004 conf/acns/2004 ACNS db/conf/acns/acns2004.html#ZhaoLZZ04