Encrypt the search index?

[dandar]

For below, can you use an encrypted search index? Encrypted by the user's password, random salt, or both?

"While Paperless encrypts the original files via the consumption script, the OCR'd text is not encrypted and is therefore stored in the clear (it needs to be searchable, so if someone has ideas on how to do that on encrypted data, I'm all ears)." --DQ

A different index per user might be ok.
Check search techniques used by proton mail or tutanota, maybe?
If needed, see a good-enough fast search index generation technique used by dokuwiki, possibly?