Vicente Benjumea Seung Geol Choi Javier Lopez Moti Yung Fair Traceable Multi-Group Signatures. 231-246 2008 Financial Cryptography http://dx.doi.org/10.1007/978-3-540-85230-8_21 conf/fc/2008 db/conf/fc/fc2008.html#BenjumeaCLY08