Resumen
The authors have plagiarized part of a paper that had already appeared in IEEE Transactions on Information Forensics and Security, 10(2), 371?383. doi:10.1109/tifs.2014.2375555. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. As such this article represents a severe abuse of the scientific publishing system. Apologies are offered to readers of the journal that this was not detected during the submission process.