@misc{cryptoeprint:2004:306,
author = {Daniel R. L. Brown and Robert P. Gallant},
title = {The Static Diffie-Hellman Problem},
howpublished = {Cryptology ePrint Archive, Report 2004/306},
year = {2004},
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.