# GenerateMac
<a name="API_GenerateMac"></a>

Generates a Message Authentication Code (MAC) cryptogram within AWS Payment Cryptography. 

You can use this operation to authenticate card-related data by using known data values to generate MAC for data validation between the sending and receiving parties. This operation uses message data, a secret encryption key and MAC algorithm to generate a unique MAC value for transmission. The receiving party of the MAC must use the same message data, secret encryption key and MAC algorithm to reproduce another MAC value for comparision.

You can use this operation to generate a DUPKT, CMAC, HMAC or EMV MAC by setting generation attributes and algorithm to the associated values. The MAC generation encryption key must have valid values for `KeyUsage` such as `TR31_M7_HMAC_KEY` for HMAC generation, and the key must have `KeyModesOfUse` set to `Generate`.

For information about valid keys for this operation, see [Understanding key attributes](https://docs.aws.amazon.com/payment-cryptography/latest/userguide/keys-validattributes.html) and [Key types for specific data operations](https://docs.aws.amazon.com/payment-cryptography/latest/userguide/crypto-ops-validkeys-ops.html) in the * AWS Payment Cryptography User Guide*. 

 **Cross-account use**: This operation can't be used across different AWS accounts.

 **Related operations:** 
+  [VerifyMac](API_VerifyMac.md) 

## Request Syntax
<a name="API_GenerateMac_RequestSyntax"></a>

```
POST /mac/generate HTTP/1.1
Content-type: application/json

{
   "GenerationAttributes": { ... },
   "KeyIdentifier": "string",
   "MacLength": number,
   "MessageData": "string"
}
```

## URI Request Parameters
<a name="API_GenerateMac_RequestParameters"></a>

The request does not use any URI parameters.

## Request Body
<a name="API_GenerateMac_RequestBody"></a>

The request accepts the following data in JSON format.

 ** [GenerationAttributes](#API_GenerateMac_RequestSyntax) **   <a name="paymentcryptographydata-GenerateMac-request-GenerationAttributes"></a>
The attributes and data values to use for MAC generation within AWS Payment Cryptography.  
Type: [MacAttributes](API_MacAttributes.md) object  
 **Note: **This object is a Union. Only one member of this object can be specified or returned.  
Required: Yes

 ** [KeyIdentifier](#API_GenerateMac_RequestSyntax) **   <a name="paymentcryptographydata-GenerateMac-request-KeyIdentifier"></a>
The `keyARN` of the MAC generation encryption key.  
Type: String  
Length Constraints: Minimum length of 7. Maximum length of 322.  
Pattern: `arn:aws:payment-cryptography:[a-z]{2}-[a-z]{1,16}-[0-9]+:[0-9]{12}:(key/[0-9a-zA-Z]{16,64}|alias/[a-zA-Z0-9/_-]+)$|^alias/[a-zA-Z0-9/_-]+`   
Required: Yes

 ** [MacLength](#API_GenerateMac_RequestSyntax) **   <a name="paymentcryptographydata-GenerateMac-request-MacLength"></a>
The length of a MAC under generation.  
Type: Integer  
Valid Range: Minimum value of 4. Maximum value of 16.  
Required: No

 ** [MessageData](#API_GenerateMac_RequestSyntax) **   <a name="paymentcryptographydata-GenerateMac-request-MessageData"></a>
The data for which a MAC is under generation. This value must be hexBinary.  
Type: String  
Length Constraints: Minimum length of 2. Maximum length of 8192.  
Pattern: `(?:[0-9a-fA-F][0-9a-fA-F])+`   
Required: Yes

## Response Syntax
<a name="API_GenerateMac_ResponseSyntax"></a>

```
HTTP/1.1 200
Content-type: application/json

{
   "KeyArn": "string",
   "KeyCheckValue": "string",
   "Mac": "string"
}
```

## Response Elements
<a name="API_GenerateMac_ResponseElements"></a>

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

 ** [KeyArn](#API_GenerateMac_ResponseSyntax) **   <a name="paymentcryptographydata-GenerateMac-response-KeyArn"></a>
The `keyARN` of the encryption key that AWS Payment Cryptography uses for MAC generation.  
Type: String  
Length Constraints: Minimum length of 70. Maximum length of 150.  
Pattern: `arn:aws:payment-cryptography:[a-z]{2}-[a-z]{1,16}-[0-9]+:[0-9]{12}:key/[0-9a-zA-Z]{16,64}` 

 ** [KeyCheckValue](#API_GenerateMac_ResponseSyntax) **   <a name="paymentcryptographydata-GenerateMac-response-KeyCheckValue"></a>
The key check value (KCV) of the encryption key. The KCV is used to check if all parties holding a given key have the same key or to detect that a key has changed.  
 AWS Payment Cryptography computes the KCV according to the CMAC specification.  
Type: String  
Length Constraints: Minimum length of 4. Maximum length of 16.  
Pattern: `[0-9a-fA-F]+` 

 ** [Mac](#API_GenerateMac_ResponseSyntax) **   <a name="paymentcryptographydata-GenerateMac-response-Mac"></a>
The MAC cryptogram generated within AWS Payment Cryptography.  
Type: String  
Length Constraints: Minimum length of 4. Maximum length of 128.  
Pattern: `[0-9a-fA-F]+` 

## Errors
<a name="API_GenerateMac_Errors"></a>

 ** AccessDeniedException **   
You do not have sufficient access to perform this action.  
HTTP Status Code: 403

 ** InternalServerException **   
The request processing has failed because of an unknown error, exception, or failure.  
HTTP Status Code: 500

 ** ResourceNotFoundException **   
The request was denied due to an invalid resource error.    
 ** ResourceId **   
The resource that is missing.
HTTP Status Code: 404

 ** ThrottlingException **   
The request was denied due to request throttling.  
HTTP Status Code: 429

 ** ValidationException **   
The request was denied due to an invalid request error.    
 ** fieldList **   
The request was denied due to an invalid request error.
HTTP Status Code: 400

## See Also
<a name="API_GenerateMac_SeeAlso"></a>

For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/payment-cryptography-data-2022-02-03/GenerateMac) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/payment-cryptography-data-2022-02-03/GenerateMac)