Microsoft Double Key Encryption (DKE) Resources

CCKM provides support for Double Key Encryption (DKE) for Microsoft 365. With DKE, two keys are used to access content (such as files or documents) that is protected with the sensitivity labels that you apply when using any one of the supported Microsoft Office apps. You hold one key in CCKM, which you maintain full control over using Microsoft’s Double Key Encryption service. The other is securely stored within Microsoft Azure. To decrypt and gain access to the protected content, both keys are required. Since Microsoft holds only one of the keys, this solution ensures that Microsoft cannot independently access this content. Only your authorized users can access the protected content.

Only your highly confidential data should be protected by DKE, which is typically a small percentage of your organization’s overall data. For more information about DKE, guidance on what type of content to protect, the supported office applications, and other information, refer to Double Key Encryption.

DKE encryption workflow

1. User adds a DKE label to a document. The Microsoft Office client connects to Azure RMS (Protection Service).

2. User certificate, API templates, and Azure RMS key are sent to the Microsoft Office client.

3. Microsoft Office client requests CCKM for the DKE public key associated with the applied label.

4. CCKM verifies the request. After authorization succeeds, CCKM sends the DKE public key to the Microsoft Office client.

5. Microsoft Office client encrypts the document content with the content key.

6. Microsoft Office client encrypts the part of the metadata that controls access to the content with the DKE public key.

7. Microsoft Office client encrypts the encrypted metadata with the Azure RMS key.

The content is protected with the double-encrypted content key, RMS key and DKE public key. The following illustration shows the DKE encryption workflow:

DKE decryption workflow

1. User opens a document which has a DKE label. The Microsoft Office client first sends the double-encrypted metadata to Azure RMS (Protection Service).

2. Azure RMS (Protection Service) decrypts the double-encrypted metadata using the Azure RMS key and returns the simple-encrypted metadata.

3. Microsoft Office client sends the simple-encrypted metadata to CCKM and requests CCKM to decrypt it.

4. CCKM verifies the request and goes through the authorization process. When authorization passes successfully, CCKM decrypts the simple-encrypted metadata and returns the decrypted metadata to the Microsoft Office client.

5. Microsoft Office client uses the content key to decrypt the document. The user can view the document content.

The following illustration shows the DKE decryption workflow:

The following are the high-level steps to configure DKE within Microsoft and CipherTrust Manager/CCKM:

1. Complete the prerequisites.

2. Configure DKE on CCKM.

3. Register your DKE service from Microsoft Azure portal.

4. Create the DKE sensitivity label and label policy.

Prerequisites

In preparation for deploying DKE, ensure that the following prerequisites are met:

1. Ensure CipherTrust Manager/CCKM is installed and running. In addition, ensure to activate and install the CCKM license. Refer to the CipherTrust Manager Deployment Guide and Licensing for details.

2. The NTP server is added. Refer to Add an NTP Server for details.

3. Install a third-party CA certificate on the web interface.

   Note

   We recommend obtaining a CA-signed certificate for the web interface from trusted CAs that are part of the Microsoft Trusted Root Program. For more information, refer to Microsoft Trusted Root Program participants.

4. Ensure the following.

   • If you have a load balancer that terminates the TLS connection and has mTLS disabled, the load balancer has a valid TLS certificate signed by a trusted CA.

   • If you have a load balancer that doesn't terminate the TLS connection or you don't have a load balancer in front of CipherTrust Manager, CipherTrust Manager has a valid TLS certificate signed by a trusted CA.

   • Additional DNS record is configured with dke. prefix and pointing to the same IP Address of the CipherTrust Manager or SSL Passthrough Load Balancer.

   • Subject Alternative Name (SAN) in the TLS certificate includes dke. prefixed DNS name, along with other DNS names associated with CipherTrust Manager or SSL Passthrough Load Balancer.

5. Microsoft 365 E5 License: Windows clients must have a Microsoft 365 E5 license. Refer to information about system and licensing requirements for DKE for more information these licensing requirements.

   Note

   CCKM supports built-in sensitivity labeling with Office apps. CCKM does not support Azure Information Protection unified labeling client, which is to be deprecated in the future.

6. User Presence in Azure Directory: Users who have to create and share documents or files protected by DKE must be part of the Azure Active Directory (Azure AD) associated with the organization's tenant.

   Note

   • DKE is tested on the Windows and iOS devices. It is not tested on macOS and Android devices.

   • To configure the B2B cross-tenant access settings, refer to Configure cross-tenant access settings for B2B collaboration.

You can now Configure DKE on CCKM.

Configure DKE on CCKM

To configure DKE on CCKM, do the following:

1. From the CCKM GUI or API, create a DKE endpoint. Refer to Creating Microsoft DKE Endpoints for details on how to create a DKE endpoint from the CCKM GUI or Creating Microsoft DKE Endpoints using the CCKM API.

   Note

   • Only Azure AD users are currently supported. The email addresses included in the API call must be associated with a user Azure AD. The email address parameter an optional field applicable only if authorization_type is set to email.

     If you specified one or more email addresses in a DKE endpoint, this field would be validated against JWT received in the decrypt operation.

   • A Microsoft Office 365 client user and email (if configured in CipherTrust Manager) must match.

   • The Issuer field must be specific to the tenant configured in the Microsoft Azure Portal.

   • The web interface port within CipherTrust Manager can be changed from the default port of 443 to another port. If you plan to change the default port for the CipherTrust Manager web interface, ensure to change it BEFORE configuring the Microsoft DKE service on CCKM. Also reflect this port change when creating a DKE endpoint on CCKM as part of the prerequisites for deploying DKE. Changing the default port AFTER configuring Microsoft DKE is not supported.

Register DKE Service

After creating a DKE endpoint, register your DKE service from the Microsoft Azure portal.

Single Tenant Application

When to Use the Single Tenant Application

Single tenant applications are only available in the tenant they were registered in, also known as their home tenant. DKE-labeled data will only be used within home tenant, configured with one CCKM environment.

For more details, refer to Tenancy in Microsoft Entra ID.

Register a Single Tenant Application

To register a single tenant application.

1. Sign in to the Microsoft Azure portal.

2. Under Azure services, click App registrations.

3. Click New registration.

4. Enter Name, like SingleTenantApplication.

5. Select Accounts in any organizational directory (Any Microsoft Entra ID tenant - Single Tenant) as the account type.

6. Under Redirect URI:

   1. Select Web as the platform.

   2. Enter the URI of CipherTrust Manager, like https://dke.thalescpl.io.

7. Click Register.

Copy the Application (client) ID and Directory (tenant) ID.

Now configure the single tenant application that includes the following.

1. Authenticate Tokens and ID Tokens

2. Adding a Certificate or Secret.

   Note

   • It is optional to add a certificate or secret.

   • You will get the credentials after adding a certificate or secret. You will need the credentials during the role-based authentication.

3. Adding an API permission.

4. Exposing an API.

5. Adding the Owner.

   Note

   It is optional to add the owner.

Authenticate Tokens and ID Tokens

To authenticate the tokens and ID tokens.

1. Go to the left pane, click Manage > Authentication.

2. Enable Access tokens

3. Enable ID Tokens.

4. Click Save.

Adding a Certificate or Secret

To add a certificate or secret.

1. Go to the left pane, click Manage > Certificates & secrets.

2. Click New client secret. The Add a client secret wizard is displayed.

3. Enter Description.

4. (Optional) Select the desired Expires (Expiry days) from the drop-down list.

5. Click Add.

Copy the Value and Secret ID of the secret. You will need the Value and Secret ID to add an Azure connection on CCKM.

Adding an API Permission

For role-based authorization, the User.Read.All and RoleManagement.Read.Directory permissions are required to retrieve user details and their assigned roles.

To add an API permission.

1. Go to the left pane, click Manage > API permissions.

2. Click Add a permission. The Request API permissions wizard is displayed.

3. Click Microsoft Graph.

4. Click Application permissions.

5. Add the User.Read.All and RoleManagement.Read.Directorypermissions.

   To add the User.Read.All permission.

   1. In the Select permissions search box, search for User.

   2. Expand User from the result.

   3. Select User.Read.All from the User list.

   To add the RoleManagement.Read.Directory permission.

   1. In the Select permissions search box, search for RoleManagement.

   2. Expand RoleManagement from the result.

   3. Select RoleManagement.Read.Directory from the RoleManagement list.

6. Click Add permissions.

7. Click Grant admin consent for {tenant}. The Grant admin consent confirmation dialog box is displayed.

8. Click Yes.

Exposing an API

Exposing an API includes adding the Application ID URI, adding a scope, and authorizing the client applications.

Adding the application ID URI.

1. Go to the left pane, click Manage > Expose an API.

2. Click Add. The Edit application ID URI is displayed.

3. Enter Application ID URI, the URI of the CipherTrust Manager.

4. Click Save.

Adding a scope.

1. Click Add a scope. The Add a scope wizard is displayed.

2. Enter Scope name, like "user_impersonation".

3. Select the Consent as Admins and users.

4. Enter Admin consent display name.

5. Enter Admin consent description.

6. (Optional) Enter User consent display name.

7. (Optional) Enter User consent description.

8. (Optional) Enable State.

9. Click Add scope.

Authorizing the client applications.

You need to authorize the Microsoft Office and Azure Information Protection applications. Perform the below steps for both the applications.

1. Click Add a client application. The Add a client application wizard is displayed.

2. Enter Client ID.

   Note

   The Client ID of Microsoft Office and Azure Information Protection applications are d3590ed6-52b3-4102-aeff-aad2292ab01c and c00e9d32-3c8d-4a7d-832b-029040e7db99, respectively.

3. Enable Authorized scopes.

4. Click Add application.

Adding the Owner

To add the owner.

1. Go to the left pane, click Manage > Owners.

2. Click Add owners.

3. Search and select the desired owner.

4. Click Select.

Multitenant Application

When to Use the Multitenant Application

Multitenant applications are available to the users in both their home tenant and other tenants. Multitenant application can be used for the following.

• Cross-tenant access for B2B collaboration.

• Sharing one DKE endpoint across multiple Azure tenants.

• Using one CCKM environment for supporting DKE in multiple Azure tenants. For example Managed Service Providers need to create a multitenant application when their customers share one CCKM environment.

For more details, refer to Tenancy in Microsoft Entra ID.

Register a Multitenant Application

To create a multitenant application.

1. Sign in to the Microsoft Azure portal.

2. Go to the left pane, click Authentication.

3. Click App registrations.

4. Click New registration.

5. Enter Name, like MultiTenantApplication.

6. Select Accounts in any organizational directory (Any Microsoft Entra ID tenant - Multitenant) as the account type.

7. Under Redirect URI:

   1. Select Web as the platform

   2. Enter the URI of CipherTrust Manager, like https://dke.thalescpl.io.

8. Click Register.

Copy the Application (client) ID and Directory (tenant) ID.

Now configure the multitenant application that includes the following.

1. Authenticate Tokens and ID Tokens

2. Adding a Certificate or Secret.

   Note

   • It is optional to add a certificate or secret.

   • You will get the credentials after adding a certificate or secret. You will need the credentials during the role-based authentication.

3. Adding an API permission.

4. Exposing an API.

5. Adding the Owner.

   Note

   It is optional to add the owner.

Authenticate Tokens and ID Tokens

To authenticate the tokens and ID tokens.

1. Go to the left pane, click Manage > Authentication.

2. Enable Access tokens

3. Enable ID Tokens.

4. Click Save.

Adding a Certificate or Secret

To add a certificate or secret.

1. Go to the left pane, click Manage > Certificates & secrets.

2. Click New client secret. The Add a client secret wizard is displayed.

3. Enter Description.

4. (Optional) Select the desired Expires (Expiry days) from the drop-down list.

5. Click Add.

Copy the Value and Secret ID of the secret. You will need the Value and Secret ID to add an Azure connection on CCKM.

Adding an API Permission

For role-based authorization, the User.Read.All and RoleManagement.Read.Directory permissions are required to retrieve user details and their assigned roles.

To add an API permission.

1. Go to the left pane, click Manage > API permissions.

2. Click Add a permission. The Request API permissions wizard is displayed.

3. Click Microsoft Graph.

4. Click Application permissions.

5. Add the User.Read.All and RoleManagement.Read.Directorypermissions.

   To add the User.Read.All permission.

   1. In the Select permissions search box, search for User.

   2. Expand User from the result.

   3. Select User.Read.All from the User list.

   To add the RoleManagement.Read.Directory permission.

   1. In the Select permissions search box, search for RoleManagement.

   2. Expand RoleManagement from the result.

   3. Select RoleManagement.Read.Directory from the RoleManagement list.

6. Click Add permissions.

7. Click Grant admin consent for {tenant}. The Grant admin consent confirmation dialog box is displayed.

8. Click Yes.

Exposing an API

Exposing an API includes adding the Application ID URI, adding a scope, and authorizing the client applications.

Adding the application ID URI.

1. Go to the left pane, click Manage > Expose an API.

2. Click Add. The Edit application ID URI is displayed.

3. Enter Application ID URI, the URI of the CipherTrust Manager.

4. Click Save.

Adding a scope.

1. Click Add a scope. The Add a scope wizard is displayed.

2. Enter Scope name, like "user_impersonation".

3. Select the Consent as Admins and users.

4. Enter Admin consent display name.

5. Enter Admin consent description.

6. (Optional) Enter User consent display name.

7. (Optional) Enter User consent description.

8. (Optional) Enable State.

9. Click Add scope.

Authorizing the client applications.

You need to authorize the Microsoft Office and Azure Information Protection applications. Perform the below steps for both the applications.

1. Click Add a client application. The Add a client application wizard is displayed.

2. Enter Client ID.

   Note

   The Client ID of Microsoft Office and Azure Information Protection applications are d3590ed6-52b3-4102-aeff-aad2292ab01c and c00e9d32-3c8d-4a7d-832b-029040e7db99, respectively.

3. Enable Authorized scopes.

4. Click Add application.

Adding the Owner

To add the owner.

1. Go to the left pane, click Manage > Owners.

2. Click Add owners.

3. Search and select the desired owner.

4. Click Select.