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Manage Customer Keys with Azure Key Vault

On this page

  • Enable Customer-Managed Keys with Azure Key Vault
  • Key Concepts
  • Required Access
  • Prerequisites
  • Enable Customer-Managed Keys for a Project
  • Enable Customer Key Management for an Atlas Cluster
  • Disable Customer-Managed Keys for a Project
  • Revoke Access to an Encryption Key
  • Alerts
  • Rotate your Azure Key Identifier
  • MongoDB Master Key - MongoDB Responsibility
  • Rotate your Azure Key ID - Your Responsibility
  • Prerequisites
  • Procedure
  • Alerts
  • Azure Key Vault Failover During an Outage
  • Related Topics

Note

  • This feature is not available for M0 free clusters, M2, and M5 clusters. To learn more, see Atlas M0 (Free Cluster), M2, and M5 Limits.

  • This feature is not supported on Serverless instances at this time. To learn more, see Serverless Instance Limitations.

Atlas uses your Azure Key Identifier (AKI) from your Azure Key Vault (AKV) to encrypt and decrypt your MongoDB master keys. These MongoDB master keys are used to encrypt cluster database files and cloud providers snapshots.

When you use your own cloud provider KMS, Atlas automatically rotates the MongoDB master key (or DEK) every 90 days. These keys are rotated on a rolling basis and the process does not require the data to be rewritten.

Atlas encrypts your data at rest using encrypted storage media. Using keys you manage with AKV, Atlas encrypts your data a second time when it writes it to the MongoDB encrypted storage engine. You use your AKI to encrypt the MongoDB master encryption keys.

This page covers configuring customer key management using AKV on your Atlas project.

You must configure customer key management for the Atlas project before enabling it on clusters in that project.

MongoDB Master Key

MongoDB Master Key is an encryption key used by the MongoDB Server to encrypt the WiredTiger Storage Engine. The key isn't stored in the MongoDB database, but it's supplied externally through KMIP. When the MongoDB server starts, it obtains the master key from the KMIP or local file and then stores it in memory. This key is then used to decrypt the data stored in the WiredTiger storage engine.

Atlas maintains a layer that translates requests between MongoDB Server and a CMK that you created in Azure. To translate the requests, Atlas uses the layer to request the CMK to create an encrypted data encryption key (DEK). This encrypted DEK is generated per Atlas deployment.

For example, for a three node M10+ replica set as shown in the following figure, there are three unique encrypted DEKs, one per node. Atlas stores the encrypted DEK on disk on each node in the Atlas cluster. When the cluster starts up, the Atlas layer decrypts the DEK using the customer provided encryption key and supplies this to the MongoDB Server.

Atlas and AWS KMS key transfer workflow
click to enlarge
Per Database Encryption Key in a MongoDB Cluster

MongoDB Server maintains a per database encryption key in the MongoDB cluster. In the preceding figure, there are three databases on the MongoDB cluster, each of which is encrypted with a unique database encryption key. Each of these keys are then encrypted with the MongoDB Master Key.

Data Encryption Key (in cloud provider terminology) or MongoDB Master Key

Atlas uses the customer provided encryption key to create an encrypted DEK. Atlas also uses a customer key management instance to decrypt this encrypted DEK and supply the resulting plaintext key to the MongoDB Server over the wire using TLS. When MongoDB Server uses this plaintext key, it refers to it as the MongoDB Master Key, whereas a cloud provider's customer key management instance might refer to it as a DEK. To learn more about DEKs, see Data Encryption.

Customer Master Key (CMK)

Customer Master Key is a concept of a customer key management instance. CMKs are used to encrypt and decrypt a MongoDB Master Key (or DEK). The CMK exists only on the customer key management instance. To learn more about CMKs, see Customer-managed keys.

To configure customer key management, you must have Project Owner access to the project.

Users with Organization Owner access must add themselves to the project as a Project Owner.

To enable customer-managed keys with Azure Key Vault for a MongoDB project, you must:

  • Have the Tenant ID (or Directory ID) for an Active Directory tenant.

  • Have the Client ID (or Application ID) and a non-expired application Password for an Azure Application associated to the Active Directory tenant.

  • Have the Resource Group name of an Azure Resource Group containing the Key Vault.

  • Have an Active Directory Application with the role of Azure key Vault Reader assigned to it.

  • Have the Subscription ID and Key Vault Name of an Azure Key Vault. Ensure the Key Vault resource group matches the resource group name specified to Resource Group.

    The Key Vault must have the following Access Policies:

    • Key Management Operations

      • GET

    • Cryptographic Operations

      • ENCRYPT

      • DECRYPT

  • Have the Key Identifier for a key in the specified Azure Key Vault.

    Atlas uses these resources when enabling encryption at rest for a cluster in the Atlas project. Consider creating an Azure Application, Resource Group, and Key Vault specifically for use with the Atlas project.

    To learn how to configure the referenced Azure components, see the Azure Documentation.

  • To help users easily create or change a cluster, you can allow public access to the key. To narrow the scope of the key and mitigate risks, use controls such as TLS and authentication.

  • For restricted access to defined IP ranges, allow access from Atlas IP addresses and the public IP addresses of your cluster nodes.

    • Ensure Atlas can communicate with your key vault. To avoid connectivity interruptions, update your configuration whenever node IP addresses change. For example, you might need to update your inbound access rules.

    • If you restrict access to the key vault, you create more complexity when IP addresses change. For example, when you create or update a cluster, you must grant access in the Azure Key Vault to any new IP addresses. You should implement a process to remove IP addresses and keys when you delete a cluster or remove nodes.

You must enable customer key management for a project before you can enable it on a cluster in that project.

1
  1. If it is not already displayed, select the organization that contains your desired project from the Organizations menu in the navigation bar.

  2. If it is not already displayed, select your desired project from the Projects menu in the navigation bar.

  3. Click Advanced in the sidebar.

2
3
4
Client ID
Enter the Client ID (or Application ID) of the Azure application.
Tenant ID
Enter the Tenant ID (or Directory ID) of the Active Directory tenant.
Secret
Enter one of the application's non-expired Passwords.
Azure Environment
Select the Azure cloud your Active Directory tenant lives in.
5
Subscription ID
Enter the Subscription ID of the Key Vault.
Resource Group Name
Enter the Resource Group of the Key Vault.
Key Vault Name
Enter the name of the Key Vault.
6
Key Identifier

Enter the full URL for the key created in the Key Vault.

Important

The key identifier must be provided in the full Azure general format

https://{keyvault-name}.vault.azure.net/{object-type}/{object-name}/{object-version}
7

Atlas displays a banner in the Atlas console during the encryption process.

After you Enable Customer-Managed Keys for a Project, you must enable customer key management for each Atlas cluster that contains data that you want to encrypt.

Note

You must have the Project Owner role to enable customer key management for clusters in that project.

For new clusters, toggle the Manage your own encryption keys setting to Yes when you create the cluster.

For existing clusters:

1
  1. If it is not already displayed, select the organization that contains your desired project from the Organizations menu in the navigation bar.

  2. If it is not already displayed, select your desired project from the Projects menu in the navigation bar.

  3. If the Database Deployments page is not already displayed, click Database in the sidebar.

2

Depending on your Key Management Service configuration, you may have to add Atlas cluster node IP addresses to your cloud provider KMS list, so that the cluster can communicate with your KMS. To enable communication between the cluster and KMS:

  1. Send a GET request to the ipAddresses endpoint. The API endpoint returns a list of IP addresses from the existing cluster nodes, similar to the following:

    {
    "groupId": "xxx", // ObjectId
    "services": {
    "clusters": [
    {
    "clusterName": "Cluster0",
    "inbound": [
    "3.92.113.229",
    "3.208.110.31",
    "107.22.44.69"
    ],
    "outbound": [
    "3.92.113.229",
    "3.208.110.31",
    "107.22.44.69"
    ]
    }
    ]
    }
    }
  2. Add the returned IP addresses to your cloud provider's IP access list. See the prerequisites for managing customer keys with AWS, Azure, and GCP for more information.

3

For the cluster that contains data that you want to encrypt, click the ellipses ..., then select Edit Configuration.

4
  1. Expand the Additional Settings panel.

  2. Toggle the Manage your own encryption keys setting to Yes.

5
  1. Click Review Changes.

  2. Review your changes, then click Apply Changes to update your cluster.

You must disable customer key management on each cluster in a project before you can disable the feature for the project.

Important

Do not disable or delete any AKV keys that any cluster in your Atlas project uses before you have disabled customer key management within the Atlas project. If Atlas cannot access an AKV key, any data that key encrypted becomes inaccessible.

You can revoke Atlas's access to an encryption key from within AKV. Atlas automatically pauses your clusters when you revoke access to the encryption key unless your AKV IP access list restricts the Atlas control plane.

To allow automatic pausing of your cluster, you must either:

Note

MongoDB adds new Atlas control plane IP addresses over time. You must keep the IP access list updated to allow automatic cluster pausing while using an IP access list for your AKV.

If the IP access list for your AKV restricts access from the Atlas control plane when you revoke access to an encryption key, you must pause your clusters manually to revoke Atlas's access.

Atlas automatically creates an encryption key rotation alert once you configure customer key management for a project.

To reset this alert, Rotate your Azure Key Identifier.

Note

When you use your own cloud provider KMS, Atlas automatically rotates the MongoDB master key (or DEK) every 90 days. These keys are rotated on a rolling basis and the process does not require the data to be rewritten.

Atlas does not automatically rotate the Key Identifier used for Azure Key Vault.

Atlas automatically creates an encryption key rotation alert to remind you to rotate your Azure Key Identifier every 90 days by default when you enable Encryption at Rest for an Atlas project.

You can rotate CMK stored in Azure Key Vault yourself or configure your Azure Key Vault to automatically rotate your keys. If you configure automatic rotation in Azure Key Vault, the default time period for rotation is approximately 365 days.

If you have already set up an automatic rotation in Azure Key Vault and don't want to receive the Atlas alert to rotate your Azure Key Identifier every 90 days, you can modify the default alert period to be greater than 365 days.

You must create a new key in the Azure Key Vault associated to the Atlas project.

The following procedure documents how to rotate your Atlas project Key Identifier by specifying a new key identifier in Atlas.

1
  1. If it is not already displayed, select the organization that contains your desired project from the Organizations menu in the navigation bar.

  2. If it is not already displayed, select your desired project from the Projects menu in the navigation bar.

  3. Click Advanced in the sidebar.

2
3
  1. Click Azure Key Vault if the Azure Key Vault selector is not already active.

  2. Click Encryption Key if the Encryption Key selector is not already active.

  3. Enter the Azure Key Identifier in the Key Identifier field.

    Include the full URL to the new encryption key identifier. For example:

    https://mykeyvault.vault.azure.net/keys/AtlasKMSKey/a241124e3d364e9eb99fbd3e11124b23

    Important

    The encryption key must belong to the Key Vault configured for the project. Click the Key Vault section to view the currently configured Key Vault for the project.

  4. Click Update Credentials.

Atlas displays a banner in the Atlas UI during the Key Identifier rotation process. Do not delete or disable the original Key Identifier until your changes have deployed.

If the cluster uses Back Up Your Database Deployment, do not delete or disable the original Key Identifier until you validate that no snapshots used that key for encryption.

Atlas resets the encryption key rotation alert alert at the completion of this procedure.

During a regional outage, your Azure KMS region might become unavailable. If this happens, Azure automatically routes incoming KMS requests to a pre-assigned secondary region. To learn more, see Azure Key Vault Failover and Regional Pairings.

If both regions are down, you can manually migrate your key to a region outside of the regional pairing. To learn more, see Move a Key Vault across Regions.

Note

If you've enabled Encryption at Rest using Customer Key Management, you can perform encrypt and decrypt operations while at least one node is still available during the outage.

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