Wen-Guey Tzeng Zhi-Jia Tzeng Robust Key-Evolving Public Key Encryption Schemes. 61-72 2002 conf/icics/2002 ICICS http://link.springer.de/link/service/series/0558/bibs/2513/25130061.htm db/conf/icics/icics2002.html#TzengT02