@misc{cryptoeprint:2015:378,
author = {Fatemeh Ganji and Shahin Tajik and Jean-Pierre Seifert},
title = {PAC Learning of Arbiter PUFs},
howpublished = {Cryptology ePrint Archive, Report 2015/378},
year = {2015},
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.