Working with Grants Using the AWS KMS API and the AWS SDK for PHP Version 3

A grant is another mechanism for providing permissions, an alternative to the key policy. You can use grants to give long-term access that allows AWS principals to use your AWS Key Management Service (AWS KMS) customer-managed CMKs. For more information, see Using Grants.

The following examples show how to:

All the example code for the AWS SDK for PHP Version 3 is available here on GitHub.

Credentials

Before running the example code, configure your AWS credentials, as described in Credentials for the AWS SDK for PHP Version 3. Then import the AWS SDK for PHP, as described in Basic Usage Patterns of the AWS SDK for PHP Version 3.

For more information about using AWS Key Management Service (AWS KMS), see the AWS KMS Developer Guide.

Create a Grant

To create a grant for an AWS KMS CMK, use the CreateGrant operation.

Imports

require 'vendor/autoload.php';

use Aws\Kms\KmsClient; 
use Aws\Exception\AwsException;

Sample Code

$KmsClient = new Aws\Kms\KmsClient([
    'profile' => 'default',
    'version' => '2014-11-01',
    'region' => 'us-east-2'
]);

$keyId = 'arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab';
$granteePrincipal = "arn:aws:iam::111122223333:user/Alice";
$operation = ['Encrypt', 'Decrypt']; // A list of operations that the grant allows.

try {
    $result = $KmsClient->createGrant([
        'GranteePrincipal' => $granteePrincipal,
        'KeyId' => $keyId,
        'Operations' => $operation
    ]);
    var_dump($result);
} catch (AwsException $e) {
    // output error message if fails
    echo $e->getMessage();
    echo "\n";
}
 
 

View a Grant

To get detailed information about the grants on an AWS KMS CMK, use the ListGrants operation.

Imports

require 'vendor/autoload.php';

use Aws\Kms\KmsClient; 
use Aws\Exception\AwsException;

Sample Code

$KmsClient = new Aws\Kms\KmsClient([
    'profile' => 'default',
    'version' => '2014-11-01',
    'region' => 'us-east-2'
]);

$keyId = 'arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab';
$limit = 10;

try {
    $result = $KmsClient->listGrants([
        'KeyId' => $keyId,
        'Limit' => $limit,
    ]);
    var_dump($result);
} catch (AwsException $e) {
    // output error message if fails
    echo $e->getMessage();
    echo "\n";
}
 
 

Retire a Grant

To retire a grant for an AWS KMS CMK, use the RetireGrant operation. Retire a grant to clean up after you finish using it.

Imports

require 'vendor/autoload.php';

use Aws\Kms\KmsClient; 
use Aws\Exception\AwsException;

Sample Code

$KmsClient = new Aws\Kms\KmsClient([
    'profile' => 'default',
    'version' => '2014-11-01',
    'region' => 'us-east-2'
]);

$grantToken = 'Place your grant token here';


try {
    $result = $KmsClient->retireGrant([
        'GrantToken' => $grantToken,
    ]);
    var_dump($result);
} catch (AwsException $e) {
    // output error message if fails
    echo $e->getMessage();
    echo "\n";
}

//Can also identify grant to retire by a combination of the grant ID and the Amazon Resource Name (ARN) of the customer master key (CMK)
$keyId = 'arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab';
$grantId = 'Unique identifier of the grant returned during CreateGrant operation'

try {
    $result = $KmsClient->retireGrant([
        'GrantId' => $grantToken,
        'KeyId' => $keyId,
    ]);
    var_dump($result);
} catch (AwsException $e) {
    // output error message if fails
    echo $e->getMessage();
    echo "\n";
}

 

Revoke a Grant

To revoke a grant to an AWS KMS CMK, use the RevokeGrant operation. You can revoke a grant to explicitly deny operations that depend on it.

Imports

require 'vendor/autoload.php';

use Aws\Kms\KmsClient; 
use Aws\Exception\AwsException;

Sample Code

$KmsClient = new Aws\Kms\KmsClient([
    'profile' => 'default',
    'version' => '2014-11-01',
    'region' => 'us-east-2'
]);

$keyId = 'arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab';
$grantId = "grant1";

try {
    $result = $KmsClient->revokeGrant([
        'KeyId' => $keyId,
        'GrantId' => $grantId,
    ]);
    var_dump($result);
} catch (AwsException $e) {
    // output error message if fails
    echo $e->getMessage();
    echo "\n";
}