@misc{cryptoeprint:2014:850,
author = {Markku-Juhani O. Saarinen},
title = {BRUTUS: Identifying Cryptanalytic Weaknesses in CAESAR First Round Candidates},
howpublished = {Cryptology ePrint Archive, Report 2014/850},
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.