Creating KMS keys in a custom key store - AWS Key Management Service

Creating KMS keys in a custom key store

After you have created a custom key store, you can create AWS KMS keys in your key store. They must be symmetric KMS keys with key material that AWS KMS generates. You cannot create asymmetric KMS keys or KMS keys with imported key material, and you cannot use symmetric KMS keys in a custom key store to generate asymmetric data key pairs.

Use and manage the KMS keys in your custom key store the same way that you use and manage any KMS key in AWS KMS. For example, you can do any of the following:

  • Use the KMS keys for cryptographic operations.

  • Set IAM and key policies on the KMS keys.

  • Create aliases are associated with the KMS keys.

  • Attach tags to the KMS keys.

  • Enable and disable the KMS keys.

  • Schedule deletions of the KMS keys.

To create a KMS key in a custom key store, the custom key store must be connected to the associated AWS CloudHSM cluster and the cluster must contain at least two active HSMs in different Availability Zones. To find the connection status and number of HSMs, view the custom key stores page in the AWS Management Console. When using the API operations, use the DescribeCustomKeyStores operation to verify that the custom key store is connected. Use the AWS CloudHSM DescribeClusters operation to get the number of active HSMs in the cluster and their Availability Zones.

When you create a KMS key in your custom key store, AWS KMS creates the KMS key in AWS KMS. But, it creates the key material for the KMS key in the associated AWS CloudHSM cluster. Specifically, AWS KMS signs into the cluster as the kmsuser CU that you created. Then it creates a persistent, non-extractable, 256-bit Advanced Encryption Standard (AES) symmetric key in the cluster. AWS KMS sets the value of the key label attribute, which is visible only in the cluster, to Amazon Resource Name (ARN) of the KMS key.

When the command succeeds, the key state of the new KMS key is Enabled and its origin is AWS_CLOUDHSM. You cannot change the origin of any KMS key after you create it. When you view a KMS key in a custom key store in the console or by using the DescribeKey operation, you can see typical properties, like its key ID, key state, and creation date. But you can also see the custom key store ID and (optionally) the AWS CloudHSM cluster ID. For details, see Viewing KMS keys in a custom key store.

If your attempt to create a KMS key in your custom key store fails, use the error message to help you determine the cause. It might indicate that the custom key store is not connected (CustomKeyStoreInvalidStateException) or the associated AWS CloudHSM cluster doesn't have the two active HSMs that are required for this operation (CloudHsmClusterInvalidConfigurationException). For help see Troubleshooting a custom key store.

Create a KMS key in a custom key store (console)

Use the following procedure to create a AWS KMS key in a custom key store.

  1. Sign in to the AWS Management Console and open the AWS Key Management Service (AWS KMS) console at https://console.aws.amazon.com/kms.

  2. To change the AWS Region, use the Region selector in the upper-right corner of the page.

  3. In the navigation pane, choose Customer managed keys.

  4. Choose Create key.

  5. Choose Symmetric.

    You cannot create an asymmetric KMS key in a custom key store.

  6. Choose Advanced options.

  7. For Key material origin, choose Custom key store (CloudHSM).

  8. Choose Next.

  9. Select a custom key store for your new KMS key. To create a new custom key store, choose Create custom key store.

    The custom key store that you select must have a status of CONNECTED. Its associated AWS CloudHSM cluster must be active and contain at least two active HSMs in different Availability Zones.

    For help with connecting a custom key store, see Connecting and disconnecting a custom key store. For help with adding HSMs, see Adding an HSM in the AWS CloudHSM User Guide.

  10. Choose Next.

  11. Type an alias and an optional description for the KMS key.

  12. (Optional). On the Add Tags page, add tags that identify or categorize your KMS key.

    When you add tags to your AWS resources, AWS generates a cost allocation report with usage and costs aggregated by tags. Tags can also be used to control access to a KMS key. For information about tagging KMS keys, see Tagging keys and ABAC for AWS KMS.

  13. Choose Next.

  14. In the Key Administrators section, select the IAM users and roles who can manage the KMS key. For more information, see Allows Key Administrators to Administer the KMS key.

    Note

    IAM policies can give other IAM users and roles permission to use the KMS key.

  15. (Optional) To prevent these key administrators from deleting this KMS key, clear the box at the bottom of the page for Allow key administrators to delete this key.

  16. Choose Next.

  17. In the This account section, select the IAM users and roles in this AWS account that can use the KMS key in cryptographic operations. For more information, see Allows Key Users to Use the KMS key.

    Note

    IAM policies can give other IAM users and roles permission to use the KMS key.

  18. (Optional) You can allow other AWS accounts to use this KMS key for cryptographic operations. To do so, in the Other AWS accounts section at the bottom of the page, choose Add another AWS account and enter the AWS account ID of an external account. To add multiple external accounts, repeat this step.

    Note

    Administrators of the other AWS accounts must also allow access to the KMS key by creating IAM policies for their users. For more information, see Allowing users in other accounts to use a KMS key.

  19. Choose Next.

  20. Review the key settings that you chose. You can still go back and change all settings.

  21. When you're done, choose Finish to create the key.

When the procedure succeeds, the display shows the new KMS key in the custom key store that you chose. When you choose the name or alias of the new KMS key, its detail page displays the origin of the KMS key (CloudHSM), the name and ID of the custom key store, and the ID of the AWS CloudHSM cluster. If the procedure fails, an error message appears that describes the failure.

Tip

To make it easier to identify KMS keys in a custom key store, on the Customer managed keys page, add the Custom key store ID column to the display. Click the gear icon in the upper-right and select Custom key store ID.

Create a KMS key in a custom key store (API)

To create a new AWS KMS key (KMS key) in your custom key store, use the CreateKey operation. Use the CustomKeyStoreId parameter to identify your custom key store and specify an Origin value of AWS_CLOUDHSM.

You might also want to use the Policy parameter to specify a key policy. You can change the key policy (PutKeyPolicy) and add optional elements, such as a description and tags at any time.

The examples in this section use the AWS Command Line Interface (AWS CLI), but you can use any supported programming language.

The following example begins with a call to the DescribeCustomKeyStores operation to verify that the custom key store is connected to its associated AWS CloudHSM cluster. By default, this operation returns all custom keys stores in your account and Region. To describe only a particular custom key store, use the CustomKeyStoreId or CustomKeyStoreName parameter (but not both).

Before running this command, replace the example custom key store ID with a valid ID.

$ aws kms describe-custom-key-stores --custom-key-store-id cks-1234567890abcdef0 { "CustomKeyStores": [ "CustomKeyStoreId": "cks-1234567890abcdef0", "CustomKeyStoreName": "ExampleKeyStore", "CloudHsmClusterId": "cluster-1a23b4cdefg", "TrustAnchorCertificate": "<certificate string appears here>", "CreationDate": "1.499288695918E9", "ConnectionState": "CONNECTED" ], }

The next example command uses the DescribeClusters operation to verify that the AWS CloudHSM cluster that is associated with the ExampleKeyStore (cluster-1a23b4cdefg) has at least two active HSMs. If the cluster has fewer than two HSMs, the CreateKey operation fails.

$ aws cloudhsmv2 describe-clusters { "Clusters": [ { "SubnetMapping": { ... }, "CreateTimestamp": 1507133412.351, "ClusterId": "cluster-1a23b4cdefg", "SecurityGroup": "sg-865af2fb", "HsmType": "hsm1.medium", "VpcId": "vpc-1a2b3c4d", "BackupPolicy": "DEFAULT", "Certificates": { "ClusterCertificate": "-----BEGIN CERTIFICATE-----\...\n-----END CERTIFICATE-----\n" }, "Hsms": [ { "AvailabilityZone": "us-west-2a", "EniIp": "10.0.1.11", "ClusterId": "cluster-1a23b4cdefg", "EniId": "eni-ea8647e1", "StateMessage": "HSM created.", "SubnetId": "subnet-a6b10bd1", "HsmId": "hsm-abcdefghijk", "State": "ACTIVE" }, { "AvailabilityZone": "us-west-2b", "EniIp": "10.0.0.2", "ClusterId": "cluster-1a23b4cdefg", "EniId": "eni-ea8647e1", "StateMessage": "HSM created.", "SubnetId": "subnet-b6b10bd2", "HsmId": "hsm-zyxwvutsrqp", "State": "ACTIVE" }, ], "State": "ACTIVE" } ] }

This example command uses the CreateKey operation to create a KMS key the custom key store. To create a KMS key in a custom key store, you must provide the ID of the custom key store name and specify an Origin value of AWS_CLOUDHSM.

The response includes the IDs of the custom key store and the AWS CloudHSM cluster.

Before running this command, replace the example custom key store ID with a valid ID.

$ aws kms create-key --origin AWS_CLOUDHSM --custom-key-store-id cks-1234567890abcdef0 { "KeyMetadata": { "AWSAccountId": "111122223333", "Arn": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab", "CreationDate": 1.499288695918E9, "Description": "Example key", "Enabled": true, "MultiRegion": false, "KeyId": "1234abcd-12ab-34cd-56ef-1234567890ab", "KeyManager": "CUSTOMER", "KeyState": "Enabled", "KeyUsage": "ENCRYPT_DECRYPT", "Origin": "AWS_CLOUDHSM" "CloudHsmClusterId": "cluster-1a23b4cdefg", "CustomKeyStoreId": "cks-1234567890abcdef0" "KeySpec": "SYMMETRIC_DEFAULT", "CustomerMasterKeySpec": "SYMMETRIC_DEFAULT", "EncryptionAlgorithms": [ "SYMMETRIC_DEFAULT" ] } }