describeKey method

Future<DescribeKeyResponse> describeKey({
  1. required String keyId,
  2. List<String>? grantTokens,
})

Provides detailed information about a customer master key (CMK). You can run DescribeKey on a customer managed CMK or an AWS managed CMK.

This detailed information includes the key ARN, creation date (and deletion date, if applicable), the key state, and the origin and expiration date (if any) of the key material. For CMKs in custom key stores, it includes information about the custom key store, such as the key store ID and the AWS CloudHSM cluster ID. It includes fields, like KeySpec, that help you distinguish symmetric from asymmetric CMKs. It also provides information that is particularly important to asymmetric CMKs, such as the key usage (encryption or signing) and the encryption algorithms or signing algorithms that the CMK supports.

DescribeKey does not return the following information:

  • Aliases associated with the CMK. To get this information, use ListAliases.
  • Whether automatic key rotation is enabled on the CMK. To get this information, use GetKeyRotationStatus. Also, some key states prevent a CMK from being automatically rotated. For details, see How Automatic Key Rotation Works in AWS Key Management Service Developer Guide.
  • Tags on the CMK. To get this information, use ListResourceTags.
  • Key policies and grants on the CMK. To get this information, use GetKeyPolicy and ListGrants.
If you call the DescribeKey operation on a predefined AWS alias, that is, an AWS alias with no key ID, AWS KMS creates an AWS managed CMK. Then, it associates the alias with the new CMK, and returns the KeyId and Arn of the new CMK in the response.

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

Required permissions: kms:DescribeKey (key policy)

Related operations:

May throw NotFoundException. May throw InvalidArnException. May throw DependencyTimeoutException. May throw KMSInternalException.

Parameter keyId : Describes the specified customer master key (CMK).

If you specify a predefined AWS alias (an AWS alias with no key ID), KMS associates the alias with an AWS managed CMK and returns its KeyId and Arn in the response.

To specify a CMK, use its key ID, Amazon Resource Name (ARN), alias name, or alias ARN. When using an alias name, prefix it with "alias/". To specify a CMK in a different AWS account, you must use the key ARN or alias 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
  • Alias name: alias/ExampleAlias
  • Alias ARN: arn:aws:kms:us-east-2:111122223333:alias/ExampleAlias
To get the key ID and key ARN for a CMK, use ListKeys or DescribeKey. To get the alias name and alias ARN, use ListAliases.

Parameter grantTokens : A list of grant tokens.

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

Implementation

Future<DescribeKeyResponse> describeKey({
  required String keyId,
  List<String>? grantTokens,
}) async {
  ArgumentError.checkNotNull(keyId, 'keyId');
  _s.validateStringLength(
    'keyId',
    keyId,
    1,
    2048,
    isRequired: true,
  );
  final headers = <String, String>{
    'Content-Type': 'application/x-amz-json-1.1',
    'X-Amz-Target': 'TrentService.DescribeKey'
  };
  final jsonResponse = await _protocol.send(
    method: 'POST',
    requestUri: '/',
    exceptionFnMap: _exceptionFns,
    // TODO queryParams
    headers: headers,
    payload: {
      'KeyId': keyId,
      if (grantTokens != null) 'GrantTokens': grantTokens,
    },
  );

  return DescribeKeyResponse.fromJson(jsonResponse.body);
}