@misc{cryptoeprint:2006:008,
author = {James A. Muir},
title = {A Simple Left-to-Right Algorithm for the Computation of the Arithmetic Weight of Integers},
howpublished = {Cryptology ePrint Archive, Report 2006/008},
year = {2006},
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.