@misc{cryptoeprint:2013:442,
author = {Shashank Agrawal and Manoj Prabhakaran},
title = {On Fair Exchange, Fair Coins and Fair Sampling},
howpublished = {Cryptology ePrint Archive, Report 2013/442},
year = {2013},
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.