The three digits behind the bank card are the cvv number, which is a 3-digit or 4-digit number generated by the card number, expiration date and service constraint code, and is generally written in the 2-track user-defined data area of the card magnetic stripe.

CVV information is stored in the tracks of magnetic stripe bank cards. According to the information such as card number, track master account number and logo code of the issuing bank, it is encrypted by a special encryption algorithm defined by each bank, and every step is encrypted by CVKA technology to obtain the verification code.

due to the different encryption algorithms of different banks, some fake cards illegally made by using the obtained bank card information can be identified and cannot be used when the issuing bank decrypts them.

Extended information

CVV code plays a very important role. It is equivalent to the ID card of a credit card and is usually used to prove that the payer owns the credit card at the time of transaction, thus preventing credit card fraud.

Generally, CVV codes are often used in the process of credit use. For example, key operations such as card opening and activation after obtaining a credit card will use security codes. In addition, credit cards can be swiped off-line besides POS. For example, if you know the card number of the credit card and the 3-digit "CVV code" on the back of the card, you can pay for it in online or telephone transactions, so you must keep the CVV code well to prevent leakage.

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