Choose between service-managed and customer-managed encryption keys

When using Microsoft Azure Cosmos DB to store sensitive data, one important consideration is how to manage encryption keys. Azure Cosmos DB provides two options: service-managed encryption keys and customer-managed encryption keys. In this article, we will explore these two approaches and discuss their advantages and use cases.

Service-Managed Encryption Keys

Service-managed encryption keys, as the name suggests, are managed by Azure Cosmos DB itself. When you choose this option, Azure Cosmos DB automatically encrypts your data at rest using its own encryption keys. This approach provides a high level of convenience because you don’t have to worry about managing and securing encryption keys yourself.

To enable service-managed encryption keys, you simply need to configure Azure Cosmos DB with the appropriate encryption settings. The service takes care of everything else for you. It ensures that your data is encrypted on disk and also during network transit.

Service-managed encryption keys are a good choice when you don’t have specific key management requirements or if you prefer to delegate the responsibility of managing encryption keys to Azure. This option offers a balance between security and convenience, making it suitable for most scenarios.

Customer-Managed Encryption Keys

On the other hand, customer-managed encryption keys (CMEK) allow you to have more control over your encryption keys. With CMEK, you can bring your own keys or use Azure Key Vault to manage your keys securely. This option is particularly useful when you have specific compliance requirements or need to adhere to industry standards for key management.

To use customer-managed encryption keys, you first need to create an Azure Key Vault to store your encryption keys. You can then configure Azure Cosmos DB to use this key vault for encryption and decryption operations. Azure Cosmos DB will leverage the keys stored in the key vault to encrypt and decrypt your data as needed.

Customer-managed encryption keys provide an additional layer of security because you have full control over the keys and can revoke or rotate them whenever required. This makes CMEK suitable for scenarios where you need to meet regulatory and compliance requirements.

Here’s an example of how you can configure Azure Cosmos DB to use customer-managed encryption keys with Azure Key Vault:

In this example, you would replace the and placeholders with the appropriate values for your Azure Key Vault.

Key Considerations

When deciding between service-managed and customer-managed encryption keys in Azure Cosmos DB, there are several factors to consider:

• Security Requirements: If you have specific compliance or regulatory requirements that necessitate control over encryption keys, customer-managed encryption keys are the way to go.
• Convenience vs. Control: Service-managed encryption keys provide the convenience of not having to manage keys yourself. If you prioritize ease of use over fine-grained control, this option may be more suitable.
• Key Rotation: With customer-managed encryption keys, you can easily rotate or revoke keys as needed. This is an essential security practice, especially if keys get compromised or employees with access to keys leave the organization.
• Cost: Customer-managed encryption keys might introduce additional costs for managing and using Azure Key Vault. Evaluate the cost implications based on your requirements and budget.

It’s important to carefully assess your specific needs and security requirements when choosing between service-managed and customer-managed encryption keys in Azure Cosmos DB. Both options offer different levels of control and convenience, so choose the one that aligns best with your use case.

In summary, service-managed encryption keys provide convenience and security while offloading the key management responsibilities to Azure Cosmos DB. On the other hand, customer-managed encryption keys give you more control and enable you to meet specific compliance requirements. Consider your security needs and preferences to make an informed decision about encryption key management in Azure Cosmos DB.