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# CVV2 为特定卡片生成或验证
<a name="use-cases-issuers.generalfunctions.cvv2"></a>

[CVV2](terminology.md#terms.cvv2)是传统上在卡背面提供的价值，用于在线购物。对于虚拟卡，它也可能显示在应用程序或屏幕上。从密码学上讲，它与服务代码值相同， CVV1 但具有不同的服务代码值。

## 创建密钥
<a name="use-cases-issuers.generalfunctions.cvv2.setup"></a>

```
$ aws payment-cryptography create-key --exportable --key-attributes KeyAlgorithm=TDES_2KEY,KeyUsage=TR31_C0_CARD_VERIFICATION_KEY,KeyClass=SYMMETRIC_KEY,KeyModesOfUse='{Generate=true,Verify=true}' --tags='[{"Key":"KEY_PURPOSE","Value":"CVV2"},{"Key":"CARD_BIN","Value":"12345678"}]'
```

响应会回显请求参数，包括后续调用的 ARN 以及密钥检查值 (KCV)。

```
{
               "Key": {
                   "KeyArn": "arn:aws:payment-cryptography:us-east-2:111122223333:key/7f7g4spf3xcklhzu",
                   "KeyAttributes": {
                       "KeyUsage": "TR31_C0_CARD_VERIFICATION_KEY",
                       "KeyClass": "SYMMETRIC_KEY",
                       "KeyAlgorithm": "TDES_2KEY",
                       "KeyModesOfUse": {
                           "Encrypt": false,
                           "Decrypt": false,
                           "Wrap": false,
                           "Unwrap": false,
                           "Generate": true,
                           "Sign": false,
                           "Verify": true,
                           "DeriveKey": false,
                           "NoRestrictions": false
                       }
                   },
                   "KeyCheckValue": "AEA5CD",
                   "KeyCheckValueAlgorithm": "ANSI_X9_24",
                   "Enabled": true,
                   "Exportable": true,
                   "KeyState": "CREATE_COMPLETE",
                   "KeyOrigin": "AWS_PAYMENT_CRYPTOGRAPHY",
                   "CreateTimestamp": "2023-06-05T06:41:46.648000-07:00",
                   "UsageStartTimestamp": "2023-06-05T06:41:46.626000-07:00"
               }
           }
```

注意代表密钥的那个`KeyArn`，例如 *arn: aws: payment-cryptography: us-east-2:* 111122223333: key/7f7g4spf3xcklhzu。您需要在下一步中执行该操作。

## 生成一个 CVV2
<a name="use-cases-issuers.generalfunctions.cvv2.generate"></a>

**Example**  
在此示例中，我们将[CVV2](terminology.md#terms.cvv2)为给定的 PAN 生成一个，其输入值为`PAN`和卡片到期日期。  
有关所有可用参数，请参阅 API 参考指南中的 [CardVerificationValue2](https://docs.aws.amazon.com/payment-cryptography/latest/DataAPIReference/API_CardVerificationValue2.html)。  

```
$ aws payment-cryptography-data generate-card-validation-data --key-identifier arn:aws:payment-cryptography:us-east-2:111122223333:key/7f7g4spf3xcklhzu --primary-account-number=171234567890123 --generation-attributes CardVerificationValue2='{CardExpiryDate=1127}'
```

```
                     {
                         "KeyArn": "arn:aws:payment-cryptography:us-east-2:111122223333:key/7f7g4spf3xcklhzu",
                         "KeyCheckValue": "AEA5CD",
                         "ValidationData": "321"
                     }
```

## 验证 CVV2
<a name="use-cases-issuers.generalfunctions.cvv2.verify"></a>

**Example**  
在此示例中，我们将使用输入的 CVK、卡到期日期`PAN`和交易期间提供的 CVV 来验证给定的 PAN 以进行验证。[CVV2](terminology.md#terms.cvv2)  
有关所有可用参数，请参阅 API 参考指南中的 [CardVerificationValue2](https://docs.aws.amazon.com/payment-cryptography/latest/DataAPIReference/API_CardVerificationValue2.html)。  
CVV2 其他输入是用户输入的值。因此，这不一定是定期无法验证的问题的迹象。

```
$ aws payment-cryptography-data verify-card-validation-data --key-identifier arn:aws:payment-cryptography:us-east-2:111122223333:key/7f7g4spf3xcklhzu --primary-account-number=171234567890123 --verification-attributes CardVerificationValue2='{CardExpiryDate=1127} --validation-data 321
```

```
{
                       "KeyArn": "arn:aws:payment-cryptography:us-east-2:111122223333:key/7f7g4spf3xcklhzu",
                       "KeyCheckValue": "AEA5CD",
                       "ValidationData": "801"
   }
```