Resumen
The authors have plagiarized part of a paper that had already appeared in IEEE Transactions on Dependable and Secure Computing, 12(3), 270?283. doi:10.1109/tdsc.2013.2297709 . 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. Apologies are offered to readers of the journal that this was not detected during the submission process.