Introduces missing CLSAG checks. The only difference now should be the
additional rejection of torsioned points, which is relevant to
https://github.com/serai-dex/serai/issues/25. Considering this is only
currently used for FROST verification, this should be fine.
Closes https://github.com/serai-dex/serai/issues/19 by making it
irrelevant.
Increases priority of https://github.com/serai-dex/serai/issues/68, as
now it's used for the BP generators which are done at first-proof.
Also merges BP's stricter hash_to_point with the library's, since CLSAG
has the same bound.
While it was fine as-is, as it only had one variable length property,
this is a bit more robust. Also binds the Curve ID, which should declare
differently even for just different basepoints, and therefore adds two
variable length properties (justifying the transcript).
Honestly, the borrowed keys are frustrating, and this probably reduces
performance while no longer offering an order when iterating. That said,
they enable full u16 indexing and should mildly improve the API.
Cleans the Proof of Knowledge handling present in key gen.
