Detlef Hühnlein Sachar Paulus On the Implementation of Cryptosystems Based on Real Quadratic Number Fields. 288-302 2000 conf/sacrypt/2000 Selected Areas in Cryptography http://link.springer.de/link/service/series/0558/bibs/2012/20120288.htm db/conf/sacrypt/sacrypt2000.html#HuhnleinP00