Control techniques are elusive by their very definition and use technology almost invisible in order to retrieve information useful for the identification and subsequent repression. To do this for some time the authorities prefer indiscriminate methods, which do mass screening, trying to present the need for siffate practices as necessary, and at the same time violating the freedom and individual privacy. One of the last cases found is that of the Machine Identification Code Technology project developed and disseminated by the Electronic Frontier Foundation. The study reveals the methods that manufacturers of printers have been forced to implement, inputting codes are invisible to the naked eye that uniquely identify the machine that produced them, and therefore its possessor. The EFF has drawn detailed decoding tables that allow to reconstruct the meanings expressed by a matrix of yellow dots, usually visible only with a microscope. In addition to invite users to print and send the appropriate test sheets to extend the test as much as possible, the organization provides a list of printers indicted and of those, however, not equipped with this type of mechanism, in addition to a web software that online allows you to decode the array of dots 'signage' rebuilding those produced by your printer. All tools needed not only to extend the awareness of these abuses, but also to attract attention and efforts to effectively combat them.