@misc{cryptoeprint:2006:117,
author = {Daniel R. L. Brown},
title = {Conjectured Security of the ANSI-NIST Elliptic Curve RNG},
howpublished = {Cryptology ePrint Archive, Report 2006/117},
year = {2006},
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.