@misc{cryptoeprint:2013:756,
author = {Yonglin Hao, Dongxia Bai},
title = {A Meet-in-the-middle Attack on Round-Reduced mCrypton},
howpublished = {Cryptology ePrint Archive, Report 2013/756},
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.