Jan Camenisch Ueli M. Maurer Markus Stadler Digital Payment Systems with Passive Anonymity-Revoking Trustees. 33-43 1996 conf/esorics/1996 ESORICS http://dx.doi.org/10.1007/3-540-61770-1_26 db/conf/esorics/esorics1996.html#CamenischMS96