@misc{cryptoeprint:2013:736,
author = {Jean-Marie Chauvet},
title = {TRS-80 With A Keccak Sponge Cake},
howpublished = {Cryptology ePrint Archive, Report 2013/736},
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.