Implement Always Encrypted

Introduction

Always Encrypted is a powerful feature in Microsoft Azure Cosmos DB that provides an additional layer of security for sensitive data. With Always Encrypted, data is encrypted at rest and in transit, ensuring that even the database administrators or anyone with unauthorized access cannot access the plaintext data.

Implementation Steps

Step 1: Provision an Azure Cosmos DB account

First, create an Azure Cosmos DB account if you don’t already have one. You can do this through the Azure portal or programmatically using the Azure SDKs.

Step 2: Create a container with encryption enabled

Next, create a container in your Azure Cosmos DB account and enable encryption for the container. You can do this by defining a container with a partition key and specifying the encryption settings. Here’s an example of container creation using the Azure Cosmos DB SDK for .NET:

var client = new CosmosClient("connection-string");
var database = await client.CreateDatabaseIfNotExistsAsync("my-database");
var containerResponse = await database.CreateContainerIfNotExistsAsync(
"my-container",
"/partitionKey",
new ThroughputProperties(400));

var response = await containerResponse.Container.Encryption().EnableEncryptionAsync(
new EncryptionOptions
{
DataEncryptionKeyId = "my-key-id",
EncryptionAlgorithm = CosmosEncryptionAlgorithm.AEAES_256_CBC_HMAC_SHA_256_RANDOMIZED,
PathsToEncrypt = { "sensitiveField" }
});

In the example above, the EnableEncryptionAsync method is called to enable encryption for the container. The EncryptionOptions object specifies the encryption key, algorithm, and the path to the sensitive field that needs to be encrypted.

Step 3: Generate a column encryption key in Azure Key Vault

To use Always Encrypted, you need a column encryption key. Create a column encryption key in Azure Key Vault and store it securely. Make sure to grant the necessary permissions to your Azure Cosmos DB account to access the key vault.

Step 4: Configure column encryption in your application

To configure column encryption in your application, you need to add the necessary code to fetch the column encryption key from Azure Key Vault and associate it with the sensitive field. Here’s an example of how you can retrieve the column encryption key and configure column encryption for a specific field:

var encryptionProperties = new EncryptionProperties
{
EncryptionType = "Deterministic",
EncryptionAlgorithm = CosmosEncryptionAlgorithm.AEAES_256_CBC_HMAC_SHA_256_RANDOMIZED,
ColumnEncryptionKeyId = "my-column-key-id",
ColumnEncryptionKeyVersion = "1.0"
};

var response = await containerResponse.Container.Encryption().SetEncryptionOptionsAsync(
"sensitiveField",
encryptionProperties);

In the above code, the SetEncryptionOptionsAsync method is used to specify the encryption options for the sensitiveField. The EncryptionProperties object contains the necessary information about the encryption type, algorithm, and the column encryption key.

Step 5: Perform CRUD operations on encrypted data

Once you have configured column encryption, you can perform CRUD operations on the encrypted data using the Azure Cosmos DB SDK. Here’s an example of inserting an encrypted document into the container:

var document = new
{
id = "1",
sensitiveField = "Hello, Secret!"
};

var response = await containerResponse.Container.CreateItemAsync(document, new PartitionKey("1"));

In the example above, the CreateItemAsync method is used to insert the encrypted document into the container. The sensitive field (sensitiveField) will be automatically encrypted using the configured column encryption.

With these steps, you have successfully implemented Always Encrypted in your native applications using Azure Cosmos DB. By encrypting sensitive data at rest and in transit, you can ensure the security and privacy of your data, even in the event of unauthorized access.

Note: Always Encrypted requires the use of Azure Key Vault, and additional configuration might be needed to set up Azure Key Vault and manage the access policies.

Remember to refer to Microsoft’s official documentation for a more detailed understanding and additional features of Always Encrypted in Azure Cosmos DB. Happy coding!