@misc{cryptoeprint:2011:672,
author = {Falko Strenzke},
title = {Fast and Secure Root Finding for Code-based Cryptosystems},
howpublished = {Cryptology ePrint Archive, Report 2011/672},
year = {2011},
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.