@misc{cryptoeprint:2010:074,
author = {Andrew C. Yao and Moti Yung and Yunlei Zhao},
title = {Concurrent Knowledge Extraction in the Public-Key Model},
howpublished = {Cryptology ePrint Archive, Report 2010/074},
year = {2010},
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.