@misc{cryptoeprint:2010:348,
author = {A. N. Alekseychuk},
title = {Lattice-theoretic Characterization of Secret Sharing Representable Connected Matroids},
howpublished = {Cryptology ePrint Archive, Report 2010/348},
year = {2010},
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.