@misc{cryptoeprint:2010:151,
author = {Stelian Flonta, Liviu-Cristian Miclea},
title = {Ring signature with divided private key},
howpublished = {Cryptology ePrint Archive, Report 2010/151},
year = {2010},
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.