Card security code

The Card security code is located on the back of MasterCard, Visa and Discover credit or debit cards and is typically a separate group of 3 digits to the right of the signature strip.

On American Express cards, the Card security code is a printed, not embossed, group of four digits on the front towards the right.

The card security code (CSC), sometimes called Card Verification Data (CVD), Card Verification Value (CVV or CVV2), Card Verification Value Code (CVVC), Card Verification Code (CVC or CVC2), Verification Code (V-Code or V Code), or Card Code Verification (CCV)^[1] are different terms for security features for credit or debit card transactions, providing increased protection against credit card fraud.

Types of codes

There are several types of security codes:

• The first code, called CVC1 or CVV1, is encoded on the magnetic stripe of the card and used for transactions in person. The purpose of the CVC1 or CVV1 is to ensure the data stored on the magnetic stripe of the card is valid and was generated by the issuing bank. This value is submitted as part of transactions and is verified by the issuing bank. A limitation of the CVC1 or CVV1 is that if the entire magnetic stripe is copied, rather than generated, the card can be duplicated. See the Skimming section for more details.
• The second code, and the most cited, is CVV2 or CVC2. This CSC (also known as a CCID or Credit Card ID) is often asked for by merchants for them to secure card not present transactions occurring over the Internet, by mail, fax or over the phone. In many countries in Western Europe, because of increased attempts at card fraud, it is now mandatory to provide this code when the cardholder is not present in person.^{[citation needed]}
• Contactless card and chip cards may supply their own codes generated electronically, such as iCVV or Dynamic CVV.

These codes should not be confused with the standard card account number appearing in embossed or printed digits. (The standard card number undergoes a separate validation algorithm called the Luhn algorithm which serves to determine whether a given card's number is appropriate.)

These codes should also not be confused with a card's PIN or passwords associated with MasterCard SecureCode or Verified by Visa. These codes are not printed or embedded in the card but are manually entered at the time of transaction.

Location of code

The CSC (the second type of code noted above) is a three- or four-digit value printed on the card or signature strip, but not encoded on the magnetic stripe.

• MasterCard, Visa, Diners Club, Discover, and JCB credit and debit cards have a three-digit card security code. The code 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 North American MasterCard and Visa cards feature the code in a separate panel to the right of the signature strip.^[2] This has been done to prevent overwriting of the numbers by signing the card. The codes have different names:

"CVC2" (card validation code) MasterCard,

"CVV2" (card verification value) Visa,

"CID" (card identification number) Discover.

• American Express cards have a four-digit code printed on the front side of the card above the number. It is printed flat, not embossed like the card number. This code is called:

"CID" or "unique card code"

Security benefits

Since the CSC 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 in North America, such as Sears and Staples, require the code. For American Express cards, this has been an invariable practice (for "card not present" transactions) in European Union (EU) states like Ireland and the United Kingdom since the start of 2005. This provides a level of protection to the bank/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.

Merchants who require the CVV2 for "card not present" transactions are forbidden in the USA by Visa from storing the CVV2 once the individual transaction is authorized and completed.^[3] This way, if a database of transactions is compromised, the CVV2 is not included, and the stolen card numbers are less useful. The Payment Card Industry Data Security Standard (PCI DSS) also prohibits the storage of CSC (and other sensitive authorisation data) post transaction authorisation. This applies globally to anyone who stores, processes or transmits card holder data.^[4]

Supplying the CSC code in a transaction is intended to verify that the customer has the card in their possession. Knowledge of the code proves that the customer has seen the card, or has seen a record made by somebody who saw the card.

Limitations

• The use of the CSC cannot protect against phishing scams, where the cardholder is tricked into entering the CSC among other card details via a fraudulent website. The growth in phishing has reduced the real-world effectiveness of the CSC as an anti-fraud device. There is now also a scam where a phisher has already obtained the card account 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 CSC (which is all that the phisher needs).^[5]
• Since the CSC may not be stored by the merchant for any length of time^[3] (after the original transaction in which the CSC was quoted and then authorized and completed), a merchant who needs to regularly bill a card for a regular subscription would not be able to provide the code after the initial transaction.
• Some card issuers do not yet use the CSC - although MasterCard started in 1997 and Visa in the USA had them issued by 2001. However, transactions without CSC are likely to be subjected to more stringent fraud screening, and fraudulent transactions without CSC are more likely to be resolved in favour of the cardholder.
• It is not mandatory for a merchant to require the security code for making a transaction, hence the card is still prone to fraud even if only its number is known to phishers.

Generation of card security codes

CVC1, CVV1, CVC2 and CVV2 values are generated when the card is issued. The values are calculated by encrypting the bank card number (also known as the primary account number or PAN), expiration date and service code with encryption keys (often called Card Verification Key or CVK) known only to the issuing bank, and decimalising the result.^[6][7]

See also

• Credit card fraud
• ISO 8583 (Data element #44 carries the Security Code response)

References

1. ^ "Authorize.Net - Developer Frequently Asked Questions:". http://developer.authorize.net/faqs/#7444. Retrieved 29 March 2009. 
2. ^ "Card Security Features" (PDF). Visa. http://www.visa.ca/en/merchant/pdfs/security_features.pdf. 
3. ^ ^{a b} "Rules for Visa Merchants" (doc). p. 1. http://usa.visa.com/download/merchants/pdra_form_dec2006.doc. 
4. ^ Official Source of PCI DSS Data Security Standards Documents and Payment Card Compliance Guidelines
5. ^ Urban Legends Reference Pages: Visa Fraud Investigation Scam
6. ^ "z/OS Integrated Cryptographic Service Facility Application Programmer’s Guide". IBM. March 2002. p. 209. http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/CSFB4Z20/2.4.2?SHELF=&DT=20020114105428. 
7. ^ "z/OS Integrated Cryptographic Service Facility Application Programmer’s Guide". IBM. March 2002. p. 258. http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/CSFB4Z20/2.4.5.16?SHELF=&DT=20020114105428.