@misc{cryptoeprint:2014:749,
author = {Daniel E. Holcomb and Kevin Fu},
title = {Bitline PUF: Building Native Challenge-Response PUF Capability into Any SRAM},
howpublished = {Cryptology ePrint Archive, Report 2014/749},
year = {2014},
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.