@misc{cryptoeprint:2009:057,
author = {Gregory M. Zaverucha and Douglas R. Stinson},
title = {Anonymity in Shared Symmetric Key Primitives},
howpublished = {Cryptology ePrint Archive, Report 2009/057},
year = {2009},
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.