The authority discovery module enables authorities to be discoverable
and discover other authorities to improve interconnection among them. In
order to achieve this the module needs to know when the authority set
changes, thus when a session changes.
One has to register a module as a *session handler* in order for it to
be notified of changing sessions. The order and number of these *session
handlers* **MUST** correspond to the order and number of the *session
keys*.
Commit 027d887 added the authority discovery to the `SessionHandlers`.
Given that the authority discovery module piggybacks on the Babe session
keys the commit violated the above constraint.
This commit reverts most of 027d887, leaving `core/authority-discovery`
and `srml/authority-discovery` untouched.
* Now construct_runtime must include treasury config so account is created at genesis.
* if it doesn't though it is ok, account will be created when the amount put is more than existential deposit.
In order to have authorities (validators) discover each other, they need
to publish their public addresses by their ip address on the Kademlia
Dht indexed by their public key. This payload needs to be signed by a
key identifying them as a valid authority.
Code inside `/core` does not know the current set of authorities nor
can it assume what kind of cryptography primitives are currently in use.
Instead it can retrieve its public key and the current set of
authorities from the runtime and have it sign and verify Dht payloads.
This commit enables code in `/core` to do so by introducing a srml
module and runtime api to:
1. Retrieve own public key.
2. Retrieve public keys of current authority set.
3. Sign a Dht payload.
4. Verify a Dht payload.
This commit makes the logic from the previous commit
(`core/consensus/common/primitives.ConsensusApi`)
cf80af9255 obsolete and thus removes it.
Kian Paimani