# Use `PutKeyPolicy` with an AWS SDK or CLI The following code examples show how to use `PutKeyPolicy`. ------ #### [ CLI ] **AWS CLI** **To change the key policy for a KMS key** The following `put-key-policy` example changes the key policy for a customer managed key. To begin, create a key policy and save it in a local JSON file. In this example, the file is `key_policy.json`. You can also specify the key policy as a string value of the `policy` parameter. The first statement in this key policy gives the AWS account permission to use IAM policies to control access to the KMS key. The second statement gives the `test-user` user permission to run the `describe-key` and `list-keys` commands on the KMS key. Contents of `key_policy.json`: ``` { "Version":"2012-10-17", "Id" : "key-default-1", "Statement" : [ { "Sid" : "Enable IAM User Permissions", "Effect" : "Allow", "Principal" : { "AWS" : "arn:aws:iam::111122223333:root" }, "Action" : "kms:*", "Resource" : "*" }, { "Sid" : "Allow Use of Key", "Effect" : "Allow", "Principal" : { "AWS" : "arn:aws:iam::111122223333:user/test-user" }, "Action" : [ "kms:DescribeKey", "kms:ListKeys" ], "Resource" : "*" } ] } ``` To identify the KMS key, this example uses the key ID, but you can also use a key ARN. To specify the key policy, the command uses the `policy` parameter. To indicate that the policy is in a file, it uses the required `file://` prefix. This prefix is required to identify files on all supported operating systems. Finally, the command uses the `policy-name` parameter with a value of `default`. If no policy name is specified, the default value is `default`. The only valid value is `default`. ``` aws kms put-key-policy \ --policy-name default \ --key-id 1234abcd-12ab-34cd-56ef-1234567890ab \ --policy file://key_policy.json ``` This command does not produce any output. To verify that the command was effective, use the `get-key-policy` command. The following example command gets the key policy for the same KMS key. The `output` parameter with a value of `text` returns a text format that is easy to read. ``` aws kms get-key-policy \ --policy-name default \ --key-id 1234abcd-12ab-34cd-56ef-1234567890ab \ --output text ``` Output: ``` { "Version":"2012-10-17", "Id" : "key-default-1", "Statement" : [ { "Sid" : "Enable IAM User Permissions", "Effect" : "Allow", "Principal" : { "AWS" : "arn:aws:iam::111122223333:root" }, "Action" : "kms:*", "Resource" : "*" }, { "Sid" : "Allow Use of Key", "Effect" : "Allow", "Principal" : { "AWS" : "arn:aws:iam::111122223333:user/test-user" }, "Action" : [ "kms:Describe", "kms:List" ], "Resource" : "*" } ] } ``` For more information, see [Changing a Key Policy](https://docs.aws.amazon.com/kms/latest/developerguide/key-policy-modifying.html) in the *AWS Key Management Service Developer Guide*. + For API details, see [PutKeyPolicy](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/kms/put-key-policy.html) in *AWS CLI Command Reference*. ------ #### [ PHP ] **SDK for PHP** There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/php/example_code/kms#code-examples). ``` /*** * @param string $keyId * @param string $policy * @return void */ public function putKeyPolicy(string $keyId, string $policy) { try { $this->client->putKeyPolicy([ 'KeyId' => $keyId, 'Policy' => $policy, ]); }catch(KmsException $caught){ echo "There was a problem replacing the key policy: {$caught->getAwsErrorMessage()}\n"; throw $caught; } } ``` + For API details, see [PutKeyPolicy](https://docs.aws.amazon.com/goto/SdkForPHPV3/kms-2014-11-01/PutKeyPolicy) in *AWS SDK for PHP API Reference*. ------ #### [ Python ] **SDK for Python (Boto3)** There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/kms#code-examples). ``` class KeyPolicy: def __init__(self, kms_client): self.kms_client = kms_client @classmethod def from_client(cls) -> "KeyPolicy": """ Creates a KeyPolicy instance with a default KMS client. :return: An instance of KeyPolicy initialized with the default KMS client. """ kms_client = boto3.client("kms") return cls(kms_client) def set_policy(self, key_id: str, policy: dict[str, any]) -> None: """ Sets the policy of a key. Setting a policy entirely overwrites the existing policy, so care is taken to add a statement to the existing list of statements rather than simply writing a new policy. :param key_id: The ARN or ID of the key to set the policy to. :param policy: The existing policy of the key. :return: None """ principal = input( "Enter the ARN of an IAM role to set as the principal on the policy: " ) if key_id != "" and principal != "": # The updated policy replaces the existing policy. Add a new statement to # the list along with the original policy statements. policy["Statement"].append( { "Sid": "Allow access for ExampleRole", "Effect": "Allow", "Principal": {"AWS": principal}, "Action": [ "kms:Encrypt", "kms:GenerateDataKey*", "kms:Decrypt", "kms:DescribeKey", "kms:ReEncrypt*", ], "Resource": "*", } ) try: self.kms_client.put_key_policy(KeyId=key_id, Policy=json.dumps(policy)) except ClientError as err: logger.error( "Couldn't set policy for key %s. Here's why %s", key_id, err.response["Error"]["Message"], ) raise else: print(f"Set policy for key {key_id}.") else: print("Skipping set policy demo.") ``` + For API details, see [PutKeyPolicy](https://docs.aws.amazon.com/goto/boto3/kms-2014-11-01/PutKeyPolicy) in *AWS SDK for Python (Boto3) API Reference*. ------ #### [ SAP ABAP ] **SDK for SAP ABAP** There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/sap-abap/services/kms#code-examples). ``` TRY. " iv_key_id = 'arn:aws:kms:us-east-1:123456789012:key/1234abcd-12ab-34cd-56ef-1234567890ab' " iv_policy = '{"Version":"2012-10-17", "Statement": [...]}' lo_kms->putkeypolicy( iv_keyid = iv_key_id iv_policyname = 'default' iv_policy = iv_policy ). MESSAGE 'Key policy updated successfully.' TYPE 'I'. CATCH /aws1/cx_kmsnotfoundexception. MESSAGE 'Key not found.' TYPE 'E'. CATCH /aws1/cx_kmsmalformedplydocex. MESSAGE 'Malformed policy document.' TYPE 'E'. CATCH /aws1/cx_kmskmsinternalex. MESSAGE 'An internal error occurred.' TYPE 'E'. ENDTRY. ``` + For API details, see [PutKeyPolicy](https://docs.aws.amazon.com/sdk-for-sap-abap/v1/api/latest/index.html) in *AWS SDK for SAP ABAP API reference*. ------ For a complete list of AWS SDK developer guides and code examples, see [Using this service with an AWS SDK](sdk-general-information-section.md). This topic also includes information about getting started and details about previous SDK versions.