@misc{cryptoeprint:2005:376,
author = {Carles Padro and Ignacio Gracia},
title = {Representing small identically self-dual matroids by self-dual codes},
howpublished = {Cryptology ePrint Archive, Report 2005/376},
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.