Dan Boneh Antoine Joux Phong Q. Nguyen Why Textbook ElGamal and RSA Encryption Are Insecure. 30-43 2000 conf/asiacrypt/2000 ASIACRYPT http://link.springer.de/link/service/series/0558/bibs/1976/19760030.htm db/conf/asiacrypt/asiacrypt2000.html#BonehJN00