Douglas R. Stinson Reto Strobl Provably Secure Distributed Schnorr Signatures and a (t, n) Threshold Scheme for Implicit Certificates. 417-434 2001 conf/acisp/2001 ACISP http://link.springer.de/link/service/series/0558/bibs/2119/21190417.htm db/conf/acisp/acisp2001.html#StinsonS01