@misc{cryptoeprint:2011:371,
author = {Paulo S. L. M. Barreto and Richard Lindner and Rafael Misoczki},
title = {Monoidic Codes in Cryptography},
howpublished = {Cryptology ePrint Archive, Report 2011/371},
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.