@misc{cryptoeprint:2015:553,
author = {Rafail Ostrovsky and Silas Richelson and Alessandra Scafuro},
title = {Round-Optimal Black-Box Two-Party Computation},
howpublished = {Cryptology ePrint Archive, Report 2015/553},
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.