Register custom ObjectEncryptionInterface / change encryption key?

I would like to implement a custom ObjectEncryptionInterface in addition to SseV1Encryption, SseV2Encryption, and SimpleEncryption. The reason is that I would like to modify the encryption key used by the Passwords app and instead include the user’s SAML token passed to Nextcloud by my SSO IdP. Is there a way to do this?

No, there is currently no support for custom encryption types

This has changed in the mean time.

SSEv3 allows implementing a server side encryption with a third party key .