@misc{cryptoeprint:2003:048,
author = {E. Martinez-Moro, J. Mozo-Fernandez, C. Munuera },
title = {Compounding Secret Sharing Schemes},
howpublished = {Cryptology ePrint Archive, Report 2003/048},
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.