@misc{cryptoeprint:2014:764,
author = {Jens Groth and Markulf Kohlweiss},
title = {One-out-of-Many Proofs: Or How to Leak a Secret and Spend a Coin},
howpublished = {Cryptology ePrint Archive, Report 2014/764},
year = {2014},
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.