Which of the following is NOT a method of object storage encryption?

Externally managed encryption, such as bring-your-own-key (BYOK), is a recognized method where customers manage encryption keys outside the provider's control for object storage.

File or folder encryption can be applied to data prior to upload, protecting it as it is stored as an object in object storage.

Enterprise DRM is a technology for enforcing usage rights and access policies on digital content at the application layer, not a mechanism for encrypting data stored in object storage systems. Object storage encryption methods protect data confidentiality at rest, whereas DRM controls what an authorized user can do with content after access is granted. These are distinct security functions operating at different layers.

Proxy encryption uses an intermediary service to encrypt and decrypt data as it transits to and from object storage, which is a valid object storage encryption method.

Client or application-side encryption encrypts data within the application before it is sent to object storage, making it a standard and widely used method.