GOAT Bitvm2 Node

A universal node for Operator, Challenger and Covenant Signer.

Tutorial

See Node.

Roles

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

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.
Relayer	Operated by official nodes. 1.Provide bootnode services 2 Supports asset transfer services between Layer 1 and Layer 2 of the BTVM2 system, including tracing L1 txn; calling and monitoring L2 gateway contract 3 Starting pegin processing.

BitVM2 protocol

Peg-in

sequenceDiagram
    participant U as User
    participant R as Relayer
    participant F as Committee 
    participant O as Operator
    participant A as All Roles
    participant B as Bitcoin Network
    participant L2 as Layer 2

    U->>B: Broadcast incomplete Peg-in tx
    U->>R: Send Peg-in Request
    R->>F: Generate Peg-in instance from user request
    F->>A: Generate & broadcast keypair + Musig2 Nonce
    O->>F: Generate BitVM2 tx graph & Presign Challenge 
    F->>A: Presign Take1/Take2/Disprove/Assert tx
    R->>U: Update Peg-in instance & store graph & notify user to broadcast Peg-in tx  through front end
    U->>B: Sign & broadcast  Peg-in tx
    R->>B: Monitor Peg-in tx Transaction confirmation
    R->>L2: Submit Peg-in tx_id & graph info & mint pegBTC

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Message Type

Kick-Off

sequenceDiagram
    participant U as User
    participant R as Relayer
    participant O as Operator
    participant A as All Roles
    participant B as Bitcoin Network
    participant L2 as Layer 2

    U->>L2: InitWithdraw tx (lock pegBTC & UTXO & mark graph could be used to kickoff the process)
    R->>L2: Get graph id & instance id related to initWithdraw tx
    R->>O: Notify O to sign & broadcast Kickoff tx
    O->>B: Sign & broadcast Kickoff tx
    R->>B: Monitor Kickoff tx confirmation
    R->>L2: Submit Kickoff tx to burn locked pegBTC & update contract state
    R->>A: Broadcast Kickoff tx confirmation

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Message Type

Claim

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

    R->>O: After Kickoff, notify O to do Take-1 action until challenge period timeout
    O->>B: Sign & broadcast Take-1 tx
    O->>A: Broadcast Take-1 tx confirmation
    R->>B: Monitor Take-1 tx confirmation & update graph state
    R->>L2: Submit Take-1 tx to update contract state

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Message Type

Challenge

sequenceDiagram
    participant R as Relayer
    participant C as Challenger
    participant O as Operator
    participant A as All Roles
    participant B as Bitcoin Network
    participant L2 as Layer 2
    
    R->>B: Monitor Kickoff tx confirmation 
    R->>A: Broadcast Kickoff tx confirmation
    C->>L2: Check initWithdraw validity
    C->>B: If invalid, broadcast Challenge tx
    C->>A: Send challenge notification
    O->>B: Generate & broadcast Assert tx with proof
    R->>B: Monitor Assert tx confirmation
    R->>A: Assert tx confirmation
    C->>B: Verify proof from Assert witness
    alt Proof incorrect
        C->>B: Broadcast Disprove tx
        C->>A: Broadcast Disprove tx confirmation
        R->>L2: Monitor Disprove tx confirmation
        R->>L2: Submit Disprove tx to update contract state
    else Proof correct
        Note over C: Challenge failed
        R->>O: Notify O do Take-2 action until disproving period timeout
        O->>B: broadcast Take-2
        O->>A: Broadcast Take-2 tx confirmation
        R->>L2: Monitor Take-2 tx confirmation
        R->>L2: Submit Take-2 to update contract state
    end

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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 --bootnodes /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 PegBTC 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