@misc{cryptoeprint:2015:002,
author = {S. M. Dehnavi and A. Mahmoodi Rishakani and M. R. Mirzaee Shamsabad},
title = {Characterization of MDS mappings},
howpublished = {Cryptology ePrint Archive, Report 2015/002},
year = {2015},
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.