GenerateMac (smaws-clients.Smaws_Client

val request : 
  Smaws_Lib.Context.t ->
  generate_mac_request ->
  (generate_mac_response,
    [> Smaws_Lib.Protocols.AwsJson.error
    | `DisabledException of disabled_exception
    | `DryRunOperationException of dry_run_operation_exception
    | `InvalidGrantTokenException of invalid_grant_token_exception
    | `InvalidKeyUsageException of invalid_key_usage_exception
    | `KeyUnavailableException of key_unavailable_exception
    | `KMSInternalException of kms_internal_exception
    | `KMSInvalidStateException of kms_invalid_state_exception
    | `NotFoundException of not_found_exception ])
    Stdlib.result

Generates a hash-based message authentication code (HMAC) for a message using an HMAC KMS key and a MAC algorithm that the key supports. HMAC KMS keys and the HMAC algorithms that KMS uses conform to industry standards defined in RFC 2104.

You can use value that GenerateMac returns in the VerifyMac operation to demonstrate that the original message has not changed. Also, because a secret key is used to create the hash, you can verify that the party that generated the hash has the required secret key. You can also use the raw result to implement HMAC-based algorithms such as key derivation functions. This operation is part of KMS support for HMAC KMS keys. For details, see HMAC keys in KMS in the Key Management Service Developer Guide.

Best practices recommend that you limit the time during which any signing mechanism, including an HMAC, is effective. This deters an attack where the actor uses a signed message to establish validity repeatedly or long after the message is superseded. HMAC tags do not include a timestamp, but you can include a timestamp in the token or message to help you detect when its time to refresh the HMAC.

The KMS key that you use for this operation must be in a compatible key state. For details, see Key states of KMS keys in the Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation with a KMS key in a different Amazon Web Services account, specify the key ARN or alias ARN in the value of the KeyId parameter.

Required permissions: kms:GenerateMac (key policy)

Related operations: VerifyMac

Eventual consistency: The KMS API follows an eventual consistency model. For more information, see KMS eventual consistency.