@misc{cryptoeprint:2014:007,
author = {Ethan Heilman },
title = {One Weird Trick to Stop Selfish Miners: Fresh Bitcoins, A Solution for the Honest Miner.},
howpublished = {Cryptology ePrint Archive, Report 2014/007},
year = {2014},
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.