@misc{cryptoeprint:2010:350,
author = {Vladimir Kolesnikov},
title = {A Security Enhancement and Proof for Authentication and Key Agreement (AKA)},
howpublished = {Cryptology ePrint Archive, Report 2010/350},
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.