Comment by l1k

It does enable address space separation of secret keys from user space, which some people love:

https://blog.cloudflare.com/the-linux-kernel-key-retention-s...

https://www.youtube.com/watch?v=7djRRjxaCKk

https://www.youtube.com/watch?v=lvZaDE578yc

So it's not as simple as "should not exist". I agree though that there doesn't seem to be a valid need to expose authencesn to user space.

Disclosure: I'm co-maintaining crypto/asymmetric_keys/ in the kernel and the author/presenter in the first two links is another co-maintainer.