@misc{cryptoeprint:2013:667,
author = {Tolga Acar and Lan Nguyen and Greg Zaverucha},
title = {A TPM Diffie-Hellman Oracle},
howpublished = {Cryptology ePrint Archive, Report 2013/667},
year = {2013},
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.