@misc{cryptoeprint:2005:069,
author = {V. S. Dimitrov and L. Imbert and P. K. Mishra},
title = {Fast Elliptic Curve Point Multiplication using Double-Base Chains},
howpublished = {Cryptology ePrint Archive, Report 2005/069},
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.