GOAT Bitvm2 Node

A universal node for Operator, Challenger and Covenant Signer.

Tutorial

See Node.

Architecture Overview

stateDiagram-v2
    [*] --> RPCServer 

    state RPCServer {
        state Middleware {
            [*] --> Identity
            Identity --> behaviour
            [*] --> MetricServer 
        }
        behaviour --> Store
        behaviour --> MessageHandler
    }
       
    state MessageHandler {
        [*] --> message 
        message --> Actor 
    }
    state Actor {
        [*] --> Committee 
        [*] --> Operator 
        [*] --> Challenger
        [*] --> More... 
    }
    
    state Identity {
        [*] --> client
        [*] --> p2p(KAD)
        [*] --> musig2
    }

    state Store {
        [*] --> payload 
        payload --> LocalDB(Mem)
        payload --> IPFS
    }

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Roles

There are three main roles in this protocol, Committee, Operator and Challenger.

Role	Functions
Committee	N-of-n signers for the presign transactions
Operator	Anyone can be an operator. 1. Exchange PeggleBTC to native BTC with users 2. Kickoff the reimbursement from Committee 3. Generate the preimage of the hash time lock to each watchtower 4. Exchange PegBTC to BTC with end-user via AtomicSwap
Challenger	Anyone can be a challenger 1. Verify the valid of the reimbursement from operators offchain 2. Submit the challenge transaction on Bitcoin to force the kick off to unhappy path
Watchtower	A special kind of challenger, selected from the Sequencer candidates, maintains the longest chain headers and spends the Watchtower output of the Kickoff transaction.
Verifier	Another kind of challenger. Once the kickoff is on the unhappy path, and the operator unveils all the execution trace(Circuit F below), verify finds the flow in the execution trace, and can spend the UTXO from Assert transaction, and stop the operator to continue the reimbursement.

BitVM2 protocol

Peg-in

sequenceDiagram
    participant U as User
    participant F as Committee 
    participant O as Operator
    participant B as Bitcoin Network
    participant L2 as Layer 2

    U->>B: Broadcast incomplete Peg-in tx
    F->>All: Generate & broadcast keypair + Musig2 Nonce
    O->>F: Generate BitVM2 tx graph & Presign Challenge 
    F->>All: Presign Take1/Take2/Disprove/Assert tx
    U->>B: Sign & broadcast pegin tx
    Note over B: Transaction confirmation
    F->>L2: Submit pegin txid & graph info

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Message Type

Kick-Off

sequenceDiagram
    participant O as Operator
    participant B as Bitcoin Network
    participant L2 as Layer 2

    O->>L2: initWithdraw tx (lock pegBTC & UTXO)
    Note over L2: Broadcast initWithdraw txid
    O->>B: Sign & broadcast Kickoff tx
    Note over B: Transaction confirmation
    O->>L2: Submit Kickoff tx
    Note over L2: Burn locked pegBTC & update state

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Message Type

Claim

sequenceDiagram
    participant O as Operator
    participant B as Bitcoin Network
    participant A as All Roles
    participant L2 as Layer 2

    Note over O: After Kickoff, wait for challenge period
    O->>B: Sign & broadcast Take-1 tx
    O->>A: Broadcast Take-1 tx
    Note over A: Update graph state
    O->>L2: Submit Take-1 tx
    Note over L2: Update contract state

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Message Type

Challenge

sequenceDiagram
    participant C as Challenger
    participant B as Bitcoin Network
    participant O as Operator
    participant L2 as Layer 2
    participant A as All Roles

    C->>B: Monitor unused Kickoff txids
    Note over B: Kickoff transaction confirmed
    C->>L2: Check initWithdraw validity
    C->>B: If invalid, broadcast Challenge tx
    C->>O: Send challenge notification
    O->>B: Generate & broadcast Assert tx with proof
    O->>C: Send response message
    C->>B: Verify proof from Assert witness
    alt Proof incorrect
        C->>B: Broadcast Disprove tx
        C->>A: Broadcast Disprove tx
        C->>L2: Submit Disprove tx
    else Proof correct
        Note over C: Challenge failed
        O->>B: After challenge period, broadcast Take-2
        O->>A: Broadcast Take-2
        O->>L2: Submit Take-2
    end
    Note over L2: Update state

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Message Type

Node

Run a node

./target/debug/goat-bitvm2-node

It should print out the address to listen on.

In another console, run

./target/debug/goat-bitvm2-node /ip4/127.0.0.1/tcp/50022

Replace the peer address with above.

Operation

Requirement

Committee Member: need approval from all committee members

Challenger: anyone can be a challenger

Operator: anyone who holds PeggledBTC can be an operator

Operation

1. Generate identity
2. Configure the bootnode and launch the node

Unjoin

Identity and Authentication

Generate the identity by cli.

P2P: ed25519

Committee n-of-n: musig2 (secp256k1)

Store

Local Store: Sqlite Memory Store

Scheme

Field name	Description	Field type
Peg-in txid	Peg-in Bitcoin transaction id	bytes: 32-byte
Covenant address	BitVM2 covenant address	bytes: 64-byte
Amount	The amount pegged-in	integer: 32-bit
Operator	The operator's bitcoin address	string
Step	Current step	integer: 8-bit
BitVM2 instance	BitVM2 transaction graph	string

Middleware

Define all the behaviours and metrics server.

• Peer discovery protocol: KAD
• Basic behaviours
• Custom behaviours