@misc{cryptoeprint:2015:202,
author = {Shafi Goldwasser and Yael Tauman Kalai and Sunoo Park},
title = {Adaptively Secure Coin-Flipping, Revisited},
howpublished = {Cryptology ePrint Archive, Report 2015/202},
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.