Matthew Cary Ramarathnam Venkatesan A Message Authentication Code Based on Unimodular Matrix Groups. 500-512 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2729&spage=500 2003 conf/crypto/2003 CRYPTO db/conf/crypto/crypto2003.html#CaryV03