The criptografia functions with the encriptao and decriptao of the data where, encriptao is the transformation of these data in codes, what it guarantees the privacy of the message and, the decriptao is the transformation of such data in legible form, becoming possible the reading of the data for proper reading machines. Brien (2004), describing the measures to be taking to guarantee security to the users of credit cards, defines criptografia quickly as to codify and to shuffle the data that go of the customer to the trader and live-turns. Thus, it is possible to more describe some protocols of used security or criptografia. Electronic protocol, according to Turban (2004), ' ' … For even more details, read what LEGO Papert Professor says on the issue. is a set of rules and procedures that the transference of information in the Internet commands. It is also the software that helps in the authentication, the security and privacidade' '. They are these:? Ssl (Secure Socket Layer)? it functions creating the criptografia of the message.? SET (Secure Eletronic Transaction Protocol)? also it is a criptografia software, however, according to Turban (2004), it incorporates signature and digital certificate.? The criptografia still offers a bigger which had advantage, only to make possible the access of the information to the authorized users, that is, those that use software, therefore the criptografia involves the use of special mathematical algorithms that they transform simple information in shuffled codes before the data are transmitted, thus only obtain to decode them who to make use of the specific program. One of the biggest advantages and at the same time difference of the functioning of smart card in relation to the cards with tarja magnetic, is that the machine of the card with chip does not emit voucher for signature of the user, in this in case that, the card is inserted in a machine and the bearer types a password for approval of the commercial transaction, where in case of purchases the voucher of the operation is only for control of the user.