createGrant method

Future<CreateGrantResponse> createGrant({
  1. required String granteePrincipal,
  2. required String keyId,
  3. required List<GrantOperation> operations,
  4. GrantConstraints? constraints,
  5. List<String>? grantTokens,
  6. String? name,
  7. String? retiringPrincipal,
})

Adds a grant to a customer master key (CMK). The grant allows the grantee principal to use the CMK when the conditions specified in the grant are met. When setting permissions, grants are an alternative to key policies.

To create a grant that allows a cryptographic operation only when the request includes a particular encryption context, use the Constraints parameter. For details, see GrantConstraints.

You can create grants on symmetric and asymmetric CMKs. However, if the grant allows an operation that the CMK does not support, CreateGrant fails with a ValidationException.

  • Grants for symmetric CMKs cannot allow operations that are not supported for symmetric CMKs, including Sign, Verify, and GetPublicKey. (There are limited exceptions to this rule for legacy operations, but you should not create a grant for an operation that AWS KMS does not support.)
  • Grants for asymmetric CMKs cannot allow operations that are not supported for asymmetric CMKs, including operations that generate data keys or data key pairs, or operations related to automatic key rotation, imported key material, or CMKs in custom key stores.
  • Grants for asymmetric CMKs with a KeyUsage of ENCRYPT_DECRYPT cannot allow the Sign or Verify operations. Grants for asymmetric CMKs with a KeyUsage of SIGN_VERIFY cannot allow the Encrypt or Decrypt operations.
  • Grants for asymmetric CMKs cannot include an encryption context grant constraint. An encryption context is not supported on asymmetric CMKs.
For information about symmetric and asymmetric CMKs, see Using Symmetric and Asymmetric CMKs in the AWS Key Management Service Developer Guide. For more information about grants, see Grants in the AWS Key Management Service Developer Guide .

The CMK that you use for this operation must be in a compatible key state. For details, see How Key State Affects Use of a Customer Master Key in the AWS Key Management Service Developer Guide.

Cross-account use: Yes. To perform this operation on a CMK in a different AWS account, specify the key ARN in the value of the KeyId parameter.

Required permissions: kms:CreateGrant (key policy)

Related operations:

May throw NotFoundException. May throw DisabledException. May throw DependencyTimeoutException. May throw InvalidArnException. May throw KMSInternalException. May throw InvalidGrantTokenException. May throw LimitExceededException. May throw KMSInvalidStateException.

Parameter granteePrincipal : The principal that is given permission to perform the operations that the grant permits.

To specify the principal, use the Amazon Resource Name (ARN) of an AWS principal. Valid AWS principals include AWS accounts (root), IAM users, IAM roles, federated users, and assumed role users. For examples of the ARN syntax to use for specifying a principal, see AWS Identity and Access Management (IAM) in the Example ARNs section of the AWS General Reference.

Parameter keyId : The unique identifier for the customer master key (CMK) that the grant applies to.

Specify the key ID or the Amazon Resource Name (ARN) of the CMK. To specify a CMK in a different AWS account, you must use the key ARN.

For example:

  • Key ID: 1234abcd-12ab-34cd-56ef-1234567890ab
  • Key ARN: arn:aws:kms:us-east-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab
To get the key ID and key ARN for a CMK, use ListKeys or DescribeKey.

Parameter operations : A list of operations that the grant permits.

Parameter constraints : Allows a cryptographic operation only when the encryption context matches or includes the encryption context specified in this structure. For more information about encryption context, see Encryption Context in the AWS Key Management Service Developer Guide .

Grant constraints are not applied to operations that do not support an encryption context, such as cryptographic operations with asymmetric CMKs and management operations, such as DescribeKey or RetireGrant.

Parameter grantTokens : A list of grant tokens.

For more information, see Grant Tokens in the AWS Key Management Service Developer Guide.

Parameter name : A friendly name for the grant. Use this value to prevent the unintended creation of duplicate grants when retrying this request.

When this value is absent, all CreateGrant requests result in a new grant with a unique GrantId even if all the supplied parameters are identical. This can result in unintended duplicates when you retry the CreateGrant request.

When this value is present, you can retry a CreateGrant request with identical parameters; if the grant already exists, the original GrantId is returned without creating a new grant. Note that the returned grant token is unique with every CreateGrant request, even when a duplicate GrantId is returned. All grant tokens for the same grant ID can be used interchangeably.

Parameter retiringPrincipal : The principal that is given permission to retire the grant by using RetireGrant operation.

To specify the principal, use the Amazon Resource Name (ARN) of an AWS principal. Valid AWS principals include AWS accounts (root), IAM users, federated users, and assumed role users. For examples of the ARN syntax to use for specifying a principal, see AWS Identity and Access Management (IAM) in the Example ARNs section of the AWS General Reference.

Implementation

Future<CreateGrantResponse> createGrant({
  required String granteePrincipal,
  required String keyId,
  required List<GrantOperation> operations,
  GrantConstraints? constraints,
  List<String>? grantTokens,
  String? name,
  String? retiringPrincipal,
}) async {
  ArgumentError.checkNotNull(granteePrincipal, 'granteePrincipal');
  _s.validateStringLength(
    'granteePrincipal',
    granteePrincipal,
    1,
    256,
    isRequired: true,
  );
  ArgumentError.checkNotNull(keyId, 'keyId');
  _s.validateStringLength(
    'keyId',
    keyId,
    1,
    2048,
    isRequired: true,
  );
  ArgumentError.checkNotNull(operations, 'operations');
  _s.validateStringLength(
    'name',
    name,
    1,
    256,
  );
  _s.validateStringLength(
    'retiringPrincipal',
    retiringPrincipal,
    1,
    256,
  );
  final headers = <String, String>{
    'Content-Type': 'application/x-amz-json-1.1',
    'X-Amz-Target': 'TrentService.CreateGrant'
  };
  final jsonResponse = await _protocol.send(
    method: 'POST',
    requestUri: '/',
    exceptionFnMap: _exceptionFns,
    // TODO queryParams
    headers: headers,
    payload: {
      'GranteePrincipal': granteePrincipal,
      'KeyId': keyId,
      'Operations': operations.map((e) => e.toValue()).toList(),
      if (constraints != null) 'Constraints': constraints,
      if (grantTokens != null) 'GrantTokens': grantTokens,
      if (name != null) 'Name': name,
      if (retiringPrincipal != null) 'RetiringPrincipal': retiringPrincipal,
    },
  );

  return CreateGrantResponse.fromJson(jsonResponse.body);
}