@misc{cryptoeprint:2003:062,
author = {Rana Barua and Ratna Dutta and Palash Sarkar},
title = {Extending Joux's Protocol to Multi Party Key Agreement},
howpublished = {Cryptology ePrint Archive, Report 2003/062},
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.