Before, things worked like this:
* Only signatures of Ed25519 keys could be verified
* Key encoding placed the plain binary Ed25519 key in the PEM, instead of the
key's ASN1 encoding
With this patch it now works like this:
* Ed25519 signatures are supported as before
* RSA keys are now supported too, assuming RSA-SHA256 signatures
* Both Ed25519 and RSA keys are encoded and decoded using actual PEM with ASN1
Before, there was a single key used as a personal key for all actors. Now,
things work like this:
- There are 2 keys, each time one is rotated, this way the old key remains
valid and we can freely rotate without a risk of race conditions on other
servers and end up with our posts being rejected
- The keys are explicitly instance-scope keys, all actors refer to them
- We add the ActivityPub-Actor header to all activity POSTs we send, to declare
for which specific actor our signature applies. Activities and otherwise
different payloads may have varying ways to specify attribution; using this
header will be a standard uniform way to specify the actor, regardless of
payload format. Of course, servers should make sure the actual activity is
attributed to the same actor we specified in the header. (This is important
with instance-scope keys; for personal keys it's not critical)
It already had one, but it didn't have a public key and it was using the old
mess of the Vervis.ActivityStreams module, which I'll possibly remove soon.
It's hopefully more elegant now.
This patch includes some ugliness and commented out code. Sorry for that. I'll
clean it up soon.
Basically there's a TVar holding a Vector of at most 10 AP activities. You can
freely POST stuff to /inbox, and then GET /inbox and see what you posted, or an
error description saying why your activity was rejected.
The actor key will be used for all actors on the server. It's held in a `TVar`
so that it can always be safely updated and safely retrieved (technically there
is a single writer so IORef and MVar could work, but they require extra care
while TVar is by design suited for this sort of thing).
