Raylin Tso Juan Manuel González Nieto Takeshi Okamoto Colin Boyd Eiji Okamoto Verifier-Key-Flexible Universal Designated-Verifier Signatures. 403-421 2007 conf/ima/2007 IMA Int. Conf. http://dx.doi.org/10.1007/978-3-540-77272-9_24 db/conf/ima/ima2007.html#TsoNOBO07