Jingwei Liu Rong Sun Wenping Ma Ying Li Xinmei Wang Fair Exchange Signature Schemes. 422-427 2008 AINA Workshops http://doi.ieeecomputersociety.org/10.1109/WAINA.2008.51 conf/aina/2008w db/conf/aina/ainaw2008.html#LiuSMLW08