Alexander Klimov Adi Shamir Cryptographic Applications of T-Functions. 248-261 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3006&spage=248 2003 conf/sacrypt/2003 Selected Areas in Cryptography db/conf/sacrypt/sacrypt2003.html#KlimovS03