@misc{cryptoeprint:2003:211,
author = {Nicolas T. Courtois, Louis Goubin and Jacques Patarin},
title = {SFLASHv3, a fast asymmetric signature scheme},
howpublished = {Cryptology ePrint Archive, Report 2003/211},
year = {2003},
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.