@misc{cryptoeprint:2010:171,
author = {Jiang Wu and Maire O'Neill},
title = {On Foundation and Construction of Physical Unclonable Functions},
howpublished = {Cryptology ePrint Archive, Report 2010/171},
year = {2010},
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.