@misc{cryptoeprint:2015:760,
author = {Pol Van Aubel and Daniel J. Bernstein and Ruben Niederhagen},
title = {Investigating SRAM PUFs in large CPUs and GPUs},
howpublished = {Cryptology ePrint Archive, Report 2015/760},
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.