@misc{cryptoeprint:2012:294,
author = {Daniel J. Bernstein and Tanja Lange},
title = {Two grumpy giants and a baby},
howpublished = {Cryptology ePrint Archive, Report 2012/294},
year = {2012},
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.