Notebook

SQL Server 2019 Standard Edition, Transparent Database Encryption and Azure Key Vault¶

This notebook demonstrates the use of Azure Key Vault to enable TDE on a SQL Server 2019 Standard Edition database using EKM.

Pre-requisities

Install Python
Install Azure CLI using the following command (You will need to ensure that the Python scripts folder is part of your PATH variable)
pip install --user azure-cli
Log into Azure and create and Azure AD Service Principal az login az account set --subscription <-subscription id-> az ad sp create-for-rbac -n sqlaadtde --skip-assignment
note the appID value which would be required later {"appId": "<-guid->",



"displayName": "sqlaadtde",
  
"name": "http://sqlaadtde",
  
"password": "<-guid->",
  
"tenant": "<-guid->"}

4. Create a new resource group and assign a newly created Azure Key Vault to the same resource group


    
 # Create a new resource group
    
 az group create -n "SQLTDEResourceGroup" -l "West US"
    
 # Register the Key Vault resource provider
    
 az provider register -n Microsoft.KeyVault
    
 az keyvault create --name "SQLStandardKeyVault" --resource-group "SQLTDEResourceGroup" --location "West US"

5. Register the Azure AD principl with AKV


    
 # Register the AAD principal
    
 az keyvault set-policy --name "SQLStandardKeyVault" --spn  --key-permissions get list wrapKey unwrapKey --verbose

Details about the scenario is available here.

Configure SQL Server to use EKM¶

Download and install the SQL Server Connector. (This should be done by the administrator of the SQL Server computer.) By default, the connector installs at C:\Program Files\SQL Server Connector for Microsoft Azure Key Vault. This location can be changed during setup. (If changed, adjust the scripts below.)
There is no interface for the Connector, but if it is installed successfully, the Microsoft.AzureKeyVaultService.EKM.dll is installed on the machine. This is the cryptographic EKM provider DLL that needs to be registered with SQL Server by using the CREATE CRYPTOGRAPHIC PROVIDER statement.

In [15]:

USE master;  
GO  

sp_configure 'show advanced options', 1;  
GO  
RECONFIGURE WITH OVERRIDE;  
GO  

-- Enable EKM provider  
sp_configure 'EKM provider enabled', 1;  
GO  
RECONFIGURE WITH OVERRIDE;  
GO

Commands completed successfully.

Configuration option 'show advanced options' changed from 1 to 1. Run the RECONFIGURE statement to install.

Commands completed successfully.

Configuration option 'EKM provider enabled' changed from 1 to 1. Run the RECONFIGURE statement to install.

Commands completed successfully.

Total execution time: 00:00:00.059

Register (create) the SQL Server Connector as an EKM provider with SQL Server¶

In [16]:

-- Create a cryptographic provider, using the SQL Server Connector
-- which is an EKM provider for the Azure Key Vault. This example uses 
-- the name AzureKeyVault_EKM_Prov.

CREATE CRYPTOGRAPHIC PROVIDER AzureKeyVault_EKM_Prov 
FROM FILE = 'C:\Program Files\SQL Server Connector for Microsoft Azure Key Vault\Microsoft.AzureKeyVaultService.EKM.dll';
GO

Commands completed successfully.

Total execution time: 00:00:00.022

Create a credential from your AAD Client ID and Secret that you can use to grant a SQL Server account access to your Azure key vault¶

The IDENTITY here is the name of your Azure key vault.
The SECRET here is your AAD Client ID (with the hyphens removed) and your AAD Client Secret concatenanted together
You will need to create a "New Client Secret" for your Azure AD app registration i.e. sqlaadtde, which was created above. See steps here.

In [25]:

CREATE CREDENTIAL Azure_EKM_TDE_cred
    WITH IDENTITY = 'SQLStandardKeyVault', -- for global Azure
    -- WITH IDENTITY = 'ContosoDevKeyVault.vault.usgovcloudapi.net', -- for Azure Government
    -- WITH IDENTITY = 'ContosoDevKeyVault.vault.azure.cn', -- for Azure China 21Vianet
    -- WITH IDENTITY = 'ContosoDevKeyVault.vault.microsoftazure.de', -- for Azure Germany 
	SECRET = '<combination of AAD Client ID without hyphens and AAD Client Secret>'
    FOR CRYPTOGRAPHIC PROVIDER AzureKeyVault_EKM_Prov

Commands completed successfully.

Total execution time: 00:00:00.012

Create an Asymmetric Key using the AKV Key¶

You will need to first create a Key in Azure Key Vault which can be used to create the Asymmetric Key in SQL Server



 # Create a software-protected key 

 az keyvault key create --vault-name "SQLStandardKeyVault" --name "SQLTDEKey" --protection software

In [27]:

CREATE ASYMMETRIC KEY dbAKV_Key   
FROM PROVIDER [AzureKeyVault_EKM_Prov]  
WITH PROVIDER_KEY_NAME = 'SQLTDEKey',  -- This is the KEY that was created in the Azure Key Vault
CREATION_DISPOSITION = OPEN_EXISTING;

Commands completed successfully.

Total execution time: 00:00:00.145

Now create a database and enable TDE on the database¶

In [30]:

USE master;  
-- Create a SQL Server login associated with the asymmetric key   
-- for the Database engine to use when it loads a database   
-- encrypted by TDE.  
CREATE LOGIN TDE_Login   
FROM ASYMMETRIC KEY dbAKV_Key;  
GO   

-- Alter the TDE Login to add the credential for use by the   
-- Database Engine to access the key vault  
ALTER LOGIN TDE_Login   
ADD CREDENTIAL Azure_EKM_TDE_cred ;  
GO

CREATE DATABASE dbAKVTDE;
GO  
USE dbAKVTDE;
GO

CREATE DATABASE ENCRYPTION KEY   
WITH ALGORITHM = AES_256   
ENCRYPTION BY SERVER ASYMMETRIC KEY dbAKV_Key;  -- Use the key created above
GO  

-- Alter the database to enable transparent data encryption.  
ALTER DATABASE dbAKVTDE   
SET ENCRYPTION ON;  
GO

Check if the database has been encrypted¶

In [36]:

USE MASTER  
SELECT name,provider_type, algorithm_desc FROM sys.asymmetric_keys  

-- Check which databases are encrypted using TDE  
SELECT SERVERPROPERTY('Edition') as [Edition],d.name, dek.encryption_scan_state_desc, dek.encryptor_type  
FROM sys.dm_database_encryption_keys AS dek  
JOIN sys.databases AS d  
     ON dek.database_id = d.database_id;

(1 row affected)

(3 rows affected)

Total execution time: 00:00:00.048

Out[36]:

name	provider_type	algorithm_desc
dbAKV_Key	CRYPTOGRAPHIC PROVIDER	RSA_2048

Out[36]:

Edition	name	encryption_scan_state_desc	encryptor_type
Standard Edition (64-bit)	tempdb	COMPLETE	ASYMMETRIC KEY
Standard Edition (64-bit)	dbTDE	COMPLETE	CERTIFICATE
Standard Edition (64-bit)	dbAKVTDE	COMPLETE	ASYMMETRIC KEY

Best Practices¶

To ensure quick key recovery and be able to access your data outside of Azure, we recommend the following best practices:
a. Create your encryption key locally on a local HSM device. (Make sure this is an asymmetric, RSA 2048 key so it's is supported by SQL Server.)
b. Import the encryption key to Azure Key Vault. See the steps in this article on how to do that.
c. Before using the key in Azure Key Vault for the first time, take an Azure Key Vault key backup. Learn more about the Backup-AzureKeyVaultKey command. Whenever any changes are made to the key (for example add ACLs, add tags, add key attributes), be sure to take another Azure Key Vault key backup.

Types of keys¶

There are two types of keys you can generate in Azure Key Vault that will work with SQL Server. Both are asymmetric 2048-bit RSA keys.
Software-protected: Processed in software and encrypted at rest. Operations on software-protected keys occur on Azure Virtual Machines. Recommended for keys not used in a production deployment.
HSM-protected: Created and protected by a hardware security module (HSM) for additional security.

For common troubleshooting and maintenance of the SQL Server Connector, please refer to this article.