@misc{cryptoeprint:1998:012,
author = {Ran Canetti, Shai Halevi, Amir Herzberg},
title = {Maintaining Authenticated Communication in the Presence of Break-ins},
howpublished = {Cryptology ePrint Archive, Report 1998/012},
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.