Ian F. Blake Vladimir Kolesnikov Strong Conditional Oblivious Transfer and Computing on Intervals. 515-529 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3329&spage=515 2004 conf/asiacrypt/2004 ASIACRYPT db/conf/asiacrypt/asiacrypt2004.html#BlakeK04