@misc{cryptoeprint:2010:448,
author = {Ronen Gradwohl and Noam Livne and Alon Rosen},
title = {Sequential Rationality in Cryptographic Protocols},
howpublished = {Cryptology ePrint Archive, Report 2010/448},
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.