Toru Nakanishi Hiroki Fujii Yuta Hira Nobuo Funabiki Revocable Group Signature Schemes with Constant Costs for Signing and Verifying. 463-480 2009 Public Key Cryptography http://dx.doi.org/10.1007/978-3-642-00468-1_26 conf/pkc/2009 db/conf/pkc/pkc2009.html#NakanishiFHF09