@misc{cryptoeprint:2004:339,
author = {Don Coppersmith and Nick Howgrave-Graham and S. V. Nagaraj},
title = {Divisors in Residue Classes, Constructively},
howpublished = {Cryptology ePrint Archive, Report 2004/339},
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.