Separate KFrag/CFrag proofs from their respective objects?

[fjarri]

This will mean that one can create/use non-verified kfrags/cfrags, which may be useful in performance-critical environments where one needs to process many objects from the same source, and chooses to only check some of them (some kind of streaming service, perhaps?).

[tuxxy]

This is a solid issue.
I think this gestures towards a larger refactor of (both) Umbral implementations so that the API is a bit more pristine. PyUmbral is a solid reference at the moment due to how stable it is, but the current goal (at least from my perspective) is to replace it with a Python wrapper around this one. So it makes sense to identify sensical refactor targets like the proofs, but there are many others that we can do as well.

[cygnusv]

I think that's fine. Initially they were separated, if I recall correctly. There's even a flag provide_proof for the reencryption function, so it makes sense.

[fjarri]

There was a flag, but it was never used, that's why I joined them in this implementation. But now I'm wondering if they're worth splitting. This will change the API, so we need to decide sooner rather than later, I want to keep all the API breaking possible in this version.