from https://github.com/pyca/ed25519
This makes the calculations several orders of magnitude faster, which
allows us to run the CoSi test in Travis. It also doesn't stop firmware
update for several seconds while we validate the CoSi signatures.
It's still essentially the same insecure implementation, fallible to all
the same timing attacks, and it shouldn't be used for anything except
validating public signatures of public data. But now it also takes about
as much time as it should on modern hardware.
This clarifies the intent: the project is licenced under terms
of LGPL version 3 only, but the standard headers cover only "3 or later",
so we had to rewrite them.
In the same step, we removed author information from individual files
in favor of "SatoshiLabs and contributors", and include an AUTHORS
file that lists the contributors.
Apologies to those whose names are missing; please contact us if you wish
to add your info to the AUTHORS file.
ed25519raw is moved back to trezorlib
ed25519cosi is renamed to cosi, and has a couple more functions,
with the expectation that TrezorClient.cosi_* methods will move there.
Also most code shouldn't need ed25519raw for anything, so it might get
renamed to "_ed25519" to indicate that it's a private implementation.
For now, I added a "verify" method to cosi, so that you don't need to
call into ed25519raw.checkvalid. But trezor-core's keyctl is also
using ed25519raw.publickey. I'm not sure if that's worth replicating
in cosi, or whether to just leave it be, so I'm leaving it be for now.
Importantly, new function "sign_with_privkey" does that math thing that
was part of the selftest and is also explicitly listed in keyctl.
(it's called sign_with_privkey because I expect to have a "sign" method
here that calls into Trezor)
