@misc{cryptoeprint:2005:257,
author = {Jin Hong and Woo-Hwan Kim},
title = {TMD-Tradeoff and State Entropy Loss Considerations of Streamcipher MICKEY},
howpublished = {Cryptology ePrint Archive, Report 2005/257},
year = {2005},
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.