Ben Lynn Manoj Prabhakaran Amit Sahai Positive Results and Techniques for Obfuscation. 20-39 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3027&spage=20 2004 conf/eurocrypt/2004 EUROCRYPT db/conf/eurocrypt/eurocrypt2004.html#LynnPS04