======== Rust F3 implementation.

FIP-0086

flowchart TD
subgraph s1["F3 instance"]
n1["Certificates<br>* verification<br>* creation<br><br>"]
n2["Manifest"]
n4["Cert Xchange<br>*client<br>*server"]
n6["Manifest Xchange"]
n7["Consensus<br>* state machine"]
end
n1 <--> n4
n6 --> n2
n7 <--> n1
n7 --> n8["EC instance"]
n4 <--> n9("Network")
n6 <--> n9
n2 --> n4
n2 --> n7

Pretty much all the other modules of the fast-finality gadget depend on this one. It defines:

• Participation primitives and logic
• Common interfaces and APIs, such as:
  • Consensus message validator
  • Signature verifier
  • Telemetry metrics
  • etc
• Consensus statemachine.

F3 configuration

• allows changing f3 configuration at runtime
• updates sent via libp2p

A crucial part of fast-finality that allows for quick finalization of chain prefixes.

This is the first step needed to be able to follow F3 consensus without active participation.

• Allows for requesting finality certificates
• Implements certificate verification logic

A libp2p certificate exchange server.

1. fetches requested powertables from storage
2. fetches requested certs from storage
3. marshals that into CBOR
4. sends the response over the network

Where it all comes together

• runs the consensus instance + libp2p exchange
• runs the certificate exchange client/server via libp2p
• manifest provider - f3 config updates via libp2p

1. What is a finality certificate?
   • A certificate that proves that a given chain prefix is final. It must be signed by a super-majority of a power table.