@misc{cryptoeprint:2011:526,
author = {Suresh Chari and Charanjit Jutla and Arnab Roy},
title = {Universally Composable Security Analysis of OAuth v2.0},
howpublished = {Cryptology ePrint Archive, Report 2011/526},
year = {2011},
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.