@misc{cryptoeprint:2005:189,
author = {Daniel R. L. Brown},
title = {A Weak-Randomizer Attack on RSA-OAEP with e = 3},
howpublished = {Cryptology ePrint Archive, Report 2005/189},
year = {2005},
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.