Card Security Code

Location

The CVV2 is a 3 or 4 digit value printed on the card, but not available on the magnetic stripe.

* MasterCard, Visa and Discover credit and debit cards have a 3 digit code, called the "CVC2" (card validation code), "CVV2" (card verification value) and "Cardmember ID" respectively. It is not embossed like the card number, and is always the final group of numbers printed on the back signature panel of the card. New MasterCard and Visa cards feature the "CVC2" in a separate panel to the right of the signature strip. This has been done in order to prevent overwriting of the numbers by signing the card.

* American Express cards have a 4 digit code printed on the front side of the card above the number, referred to as the "CID", or Card Identification Number. It is printed flat, not embossed like the card number.

The number is generated when the card is issued, by encrypting the card number and expiry date under a key known only to the issuing bank. Supplying this code in a transaction is intended to verify that the customer has the card in their physical possession.

Security benefits

Since the CVV2 is not contained on the magnetic stripe of the card, it is not typically included in the transaction when the card is used face to face at a merchant. However, some merchants have begun requiring the code for use of American Express cards, such as Sears and Staples.[citation needed] This provides a level of protection to the cardholder, in that a corrupt merchant cannot simply capture the magnetic stripe details of a card and use them later for "card not present" purchases over the phone, mail order or Internet. To do this, a merchant would also have to note the CVV2 visually and record it, which is more likely to arouse the cardholder's suspicion.

Online merchants who require the CVV2 in their transactions are forbidden from storing these details once the transaction is complete. This way, if a database of transactions is compromised, the CVV2 is not included, and the stolen credit card numbers are less useful.

Limitations

The use of the CVV2 cannot protect against phishing scams, where the cardholder is tricked into entering the CVV2 among other card details via a fraudulent website. The growth in phishing has reduced the real-world effectiveness of the CVV2 as an anti-fraud device. There is now also a scam where a phisher has already obtained the credit card number (perhaps by hacking a merchant database or from a poorly designed receipt) and gives this information to the victims (lulling them into a false sense of security) before asking for the CVV2 (which is all that the phisher needs).

Since the CVV2 may not be stored by the merchant, a merchant who needs to rebill a credit card for a regular subscription would not be able to provide the code after the initial transaction. This means the use of CVV2 codes must remain optional; however, transactions without CVV2 are likely to be subjected to more stringent fraud screening, and fraudulent transactions without CVV2 are more likely to be resolved in favour of the cardholder.

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