@misc{cryptoeprint:2000:068,
author = {Tak-Ming Law},
title = {A Content Certified E-mail Protocol with a Public Mailbox},
howpublished = {Cryptology ePrint Archive, Report 2000/068},
year = {2000},
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.