Renato Renner Stefan Wolf The Exact Price for Unconditionally Secure Asymmetric Cryptography. 109-125 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3027&spage=109 2004 conf/eurocrypt/2004 EUROCRYPT db/conf/eurocrypt/eurocrypt2004.html#RennerW04