@misc{cryptoeprint:2011:246,
author = {Bernardo Machado David and Anderson C. A. Nascimento and Rafael Tonicelli},
title = {A Framework for Secure Single Sign-On},
howpublished = {Cryptology ePrint Archive, Report 2011/246},
year = {2011},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.