@misc{cryptoeprint:2011:493,
author = {Nir Bitansky and Omer Paneth},
title = {From Point Obfuscation To 3-round Zero-Knowledge},
howpublished = {Cryptology ePrint Archive, Report 2011/493},
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.