@misc{cryptoeprint:2013:491,
author = {Vladimir Kolesnikov and Ranjit Kumaresan},
title = {Improved OT Extension for Transferring Short Secrets},
howpublished = {Cryptology ePrint Archive, Report 2013/491},
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.