Pan Wang Peng Ning Douglas S. Reeves Storage-Efficient Stateless Group Key Revocation. 25-38 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3225&spage=25 2004 conf/isw/2004 ISC db/conf/isw/isc2004.html#WangNR04