@misc{cryptoeprint:2013:650,
author = {Elette Boyle and Kai-Min Chung and Rafael Pass},
title = {On Extractability (a.k.a. Differing-Inputs) Obfuscation},
howpublished = {Cryptology ePrint Archive, Report 2013/650},
year = {2013},
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.