Feng Bao Robert H. Deng Khanh Quoc Nguyen Vijay Varadharajan Multi-Party Fair Exchange with an Off-Line Trusted Neutral Party. 858-863 1999 DEXA Workshop http://computer.org/conferen/proceed/dexa/0281/02810858abs.htm db/conf/dexaw/dexaw99.html#BaoDNV99