Javier Herranz Germán Sáez New Identity-Based Ring Signature Schemes. 27-39 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3269&spage=27 2004 conf/icics/2004 ICICS db/conf/icics/icics2004.html#HerranzS04