@misc{cryptoeprint:2011:488,
author = {Kai-Yuen Cheong},
title = {A Survey of Cryptography Based on Physically Unclonable Objects},
howpublished = {Cryptology ePrint Archive, Report 2011/488},
year = {2011},
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.