The last three codes, CVC(CardVerificationCode), are additional codes printed on the back of credit cards, also known as CVV. The display position is on the back of the credit card, and the top at the end of the signature is displayed in italics. The first four digits are the card number and the last three digits are the verification code, that is, the last three codes.

This kind of verification code does not refer to the password of the credit card. To book a flight by phone, you only need to enter the bank card number and the three digits behind it, as well as the validity period of the credit card. There is no password at all. At noon yesterday, the customer service staff of Ctrip.com told the reporter that the information needed to purchase air tickets by credit card is: card number, credit card validity period, "last three" verification code and cardholder ID number.

Extended data:

CVV information is stored in the track of a magnetic stripe bank card, and is encrypted by a special encryption algorithm defined by each bank according to the information such as card number, track master account number and card issuing bank logo code, 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.

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