Encryption is a technique for protecting data from unauthorized access or use by transforming it into an unreadable format. Decryption makes the data readable again. Encryption of data at rest, provided through Azure Cosmos DB, safeguards the data stored within its databases. Azure Cosmos DB supports two types of encryption keys for securing data at rest:
- Service-Managed Keys
- Customer-Managed Keys
Service-Managed Keys
In the Service-Managed encryption key method, Azure Cosmos DB manages the encryption keys. Users do not have to worry about generating, securing, or protecting the keys. Azure Cosmos DB automatically encrypts data before it is written to storage and decrypts it when reading from storage.
Pros of Service-Managed Keys:
- It’s simple to use, requiring minimal management from the user.
- Key rotation and management is automatic and not a user concern.
- No additional cost incurred other than Azure Cosmos DB charges.
Cons of Service-Managed Keys:
- Users have less control over the encryption keys.
- Limited geographical control over where data is stored.
Customer-Managed Keys
With Customer-Managed keys, users maintain control of the encryption keys in Azure Key Vault. They are responsible for creating the keys, configuring key policies, and managing key rotation. This method allows for greater control over the key, including the ability to revoke access at any time and restrict it to specific geographic locations.
Pros of Customer-Managed Keys:
- Greater control over encryption keys.
- Ability to revoke or time-bound access to the key.
- Capability to restrict key usage to specific geographic locations.
Cons of Customer-Managed Keys:
- Requires more management overhead.
- Extra charges for using Azure Key Vault and potential addition charges for key operations.
- If user-managed keys are lost, it can result in the loss of all associated data.
Making the Choice
The table below summarizes the differences between service-managed and customer-managed keys:
| Factor | Service Managed Keys | Customer Managed Keys |
|---|---|---|
| Degree of Control | Lesser | Greater |
| Management Overhead | Minimal | High |
| Geographical Restrictions | Limited | Yes |
| Cost | Only Azure Cosmos DB charges | Additional charges for Azure Key Vault usage |
| Key Rotation and Management | Automatically done | User-dependent |
Your choice of either Service-managed or Customer-managed encryption ultimately depends on your specific use case, the operational overhead you are willing to handle, and the level of control you require over your encryption keys. It is pivotal to understand these options fully and leverage the one that best suits the data security requirements of your Azure Cosmos DB native applications.
Practice Test
True or False: In Azure, customer-managed keys offer more control over encryption keys compared to service-managed keys.
- True
- False
Answer: True
Explanation: In the customer-managed keys mechanism, the users can handle the complete key lifecycle, offering comprehensive control than the service-managed key mechanism.
Which management process utilizes Azure Key Vault?
- a. Service-Managed Encryption
- b. Customer-Managed Encryption
- c. Both
- d. None
Answer: b. Customer-Managed Encryption
Explanation: The customer-managed encryption keys leverage Azure Key Vault for storing and managing the encryption keys.
True or False: Azure automatically updates the customer-managed keys.
- True
- False
Answer: False
Explanation: Azure does not automatically update customer-managed keys; it is the customer’s responsibility to rotate, update, or revoke them.
What gives you full control over the management of the encryption key lifecycle?
- a. Service-managed keys
- b. Customer-managed keys
Answer: b. Customer-managed keys
Explanation: Customer-managed keys give users the responsibility and control over the entire lifecycle, including creation, rotation, and revocation of encryption keys.
With ___________, Azure manages the key lifecycle including the creation and rotation of the keys.
- a. Service-managed keys
- b. Customer-managed keys
Answer: a. Service-managed keys
Explanation: With service-managed keys, Azure manages the entire key lifecycle, reducing the complexity for customers.
True or False: In customer-managed keys, the user cannot manage key rotation and updating.
- True
- False
Answer: False
Explanation: In customer-managed keys, the user is responsible for managing the key lifecycle, including rotation and updating.
Which key management method provides less operational overhead and is easier to use?
- a. Service-managed encryption
- b. Customer-managed encryption
Answer: a. Service-managed encryption
Explanation: Service-managed encryption keys are simpler to manage as Azure handles their lifecycle.
True or False: Service-managed keys could require customers to meet certain compliance certifications.
- True
- False
Answer: True
Explanation: Depending on a company’s industry and regulatory requirements, service-managed keys could require certain compliance certifications.
With ______________, you cannot directly access encryption keys.
- a. Customer-managed-keys
- b. Service-managed-keys
- c. Both
- d. None
Answer: b. Service-managed-keys
Explanation: In the case of service-managed keys, Azure manages the keys, and the user does not have direct access to the keys.
True or False: With customer-managed keys, Azure has no visibility or control of the encryption keys.
- True
- False
Answer: True
Explanation: In the customer-managed keys scenario, Azure is blind to the key management and rotation, it rests entirely in the hands of the customer.
Which method allows key rotation automation?
- a. Service-managed encryption
- b. Customer-managed encryption
Answer: a. Service-managed encryption
Explanation: With service-managed keys, Azure handles the rotational policy, so the keys are automatically rotated.
True or False: Service-managed keys pose a higher risk of key loss.
- True
- False
Answer: False
Explanation: The risk of key loss is lower with service-managed keys because Azure manages and backs up these keys.
Interview Questions
What is the main difference between service-managed and customer-managed encryption keys for Microsoft Azure Cosmos DB?
In service-managed keys, Microsoft manages all the key management tasks on behalf of users whereas in customer-managed keys, users have full control over the key management tasks including its rotation, revocation, auditing, etc.
What are the responsibilities of the customer when using customer-managed encryption keys for Azure Cosmos DB?
With customer-managed encryption keys, customers are responsible for creating, configuring, protecting, and managing their keys, including rotating keys, understanding and managing key versions, and handling unauthorized access to keys.
Which feature does support Azure Cosmos DB service-managed encryption keys?
Azure Cosmos DB service-managed encryption keys automatically encrypt both data at rest and data in motion.
What type of encryption is managed with customer-managed keys in Azure Cosmos DB?
The encryption of data at rest is manage with customer-managed keys in Azure Cosmos DB.
How can I access the data when using customer-managed keys to encrypt data in Azure Cosmos DB?
You can access the data by using the user data key to encrypt and decrypt data while the master key is used to encrypt the user data key.
When should a company consider using service-managed encryption keys?
When a company doesn’t have extensive needs for encryption key management and its fine with Microsoft managing their keys, then they should consider using service-managed keys.
In what situations should I choose customer-managed keys over service-managed keys?
Customer-managed keys are preferable when you need more granular control over the encryption and decryption process, for compliance requirements or when you have the capacity to handle the complexity of managing your own keys.
What is Azure Key Vault in the context of customer-managed encryption keys?
Azure Key Vault is Microsoft’s secrets management system, and it’s where customer-managed keys are stored in Azure Cosmos DB.
How does Azure Cosmos DB implement customer-managed keys?
Azure Cosmos DB integrates with Azure Key Vault, enabling customers to bring their keys to the service and control the rotation and management processes.
In terms of pricing, how does service-managed keys compare to customer-managed keys?
Using service-managed keys isn’t associated with any additional cost while using customer-managed keys can incur additional cost because it leverages Azure Key Vault for key storage and management which has its own pricing.
Can I switch from service-managed to customer-managed keys in Azure Cosmos DB?
Yes, but it requires careful planning and considerations regarding data migration and potential downtime.
How often are service-managed keys in Azure Cosmos DB rotated?
Microsoft automatically rotates service-managed keys on a regular basis (usually annually) without any action required by the customer.
How can I audit the use of my customer-managed keys in Azure Cosmos DB?
You can audit key usage by enabling Azure Key Vault logging and monitoring events in Azure Log Analytics.
What are some of the security benefits of customer-managed keys?
With customer-managed keys, users can control who has access to their keys, revoke access at any time, manage key versions, and meet compliance requirements.
Can I use both service-managed and customer-managed encryption keys in the same Azure Cosmos DB account?
No, you must choose either service-managed or customer-managed keys at the account level for each Azure Cosmos DB account.
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