What does BYOK mean?

Bring Your Own Key (BYOK) is an approach where the on prem keys are placed in a cloud service provider environment, enabling to use on prem keys with the native cloud key management services to encrypt and decrypt content. BYOK requires HSMs (either dedicated or offered as KMS service) but supports all cloud service models (SaaS, PaaS, and IaaS) so long as the cloud vendor offers key management service.

Role and Working of BYOK

Imagine BYOK as a system where you carry your own lock and key to secure valuables, even when storing them in a shared locker (like cloud storage). This analogy highlights the key role of BYOK (Bring Your Own Key) in cloud security: retaining control over your data encryption keys.

In traditional cloud storage, the cloud provider manages and encrypts the data using their own keys. BYOK allows to generate and manage your own encryption keys, typically stored in a secure device called a Hardware Security Module (HSM). Here’s how it works:-

1. Generate and store

   Create your encryption keys and securely store them in your HSM.

2. Upload (optional)

   Depending on the BYOK implementation, some solutions allow uploading the encrypted key to the cloud provider’s Key Management Service (KMS) for additional management features.

3. Encrypt and decrypt

   When you upload data to the cloud, the HSM encrypts it using your key. When you need to access the data, the HSM decrypts it using the same key.

BYOK with Cloud KMS

Organizations can bring their own ‘master’ keys to the cloud, but the cloud provider uses data encryption keys derived from the master for actual encryption and decryption outside the HSMs. As the cloud vendor controls all the underlying hardware and software, they can choose if encryption is done in hardware or software services, while maintaining security of the derived encryption keys.

Advantages

• No specialized skilled resources are required
• Enables existing products that need keys to use cryptography
• Provides centralized point to manage keys across heterogeneous products
• Native integration with other services such as system administration, databases, storage and application development tools offered by the cloud provider

Disadvantages

• Key exposure outside HSM
• FIPS 140-2 Level 3 and above devices not available

BYOK with Cloud HSM

All encryption operations on the organization’s behalf are performed inside the HSM. The native cloud encryption service may satisfy requests on the organization’s behalf, so encryption and decryption are transparent, but key access and cryptographic operations are kept within the HSM.

Advantages

• No Key exposure outside the HSM
• FIPS advanced level (FIPS 140-2 Level 3 and above) complaint hardware-based devices meeting all regulatory requirements
• Can perform all core functions of an on prem HSM -key generation, key storage, key rotation, and API interfaces to orchestrate encryption in the cloud
• Designed for security
• Dedicated hardware and software for security functions.

Disadvantages

• Need specialized in-house resources to manage key and crypto lifecycle  activities
• HSM based approaches are more cost intensive due to the dedicated hardware appliance that is made available
• Performance overheads