@misc{cryptoeprint:1998:018,
author = {Ran Canetti },
title = {Security and Composition of Multi-party Cryptographic Protocols},
howpublished = {Cryptology ePrint Archive, Report 1998/018},
year = {1998},
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.