@misc{cryptoeprint:2015:607,
author = {Hitesh Tewari and Eamon O Nuallain},
title = {Netcoin - A Traceable P2P Electronic Cash System},
howpublished = {Cryptology ePrint Archive, Report 2015/607},
year = {2015},
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.