@misc{cryptoeprint:2005:006,
author = {Pradeep Kumar Mishra and Kishan Chand Gupta},
title = {A Metric on the Set of Elliptic Curves over ${\mathbf F}_p$.},
howpublished = {Cryptology ePrint Archive, Report 2005/006},
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.