@misc{cryptoeprint:2000:049,
author = {Palash Sarkar},
title = {Spectral Domain Analysis of Correlation Immune and Resilient Boolean Functions},
howpublished = {Cryptology ePrint Archive, Report 2000/049},
year = {2000},
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.