Setup Protocol

graph LR ms-->fb subgraph off-chain state fb["<b>Free Balance</b> (ETH) <pre></pre> versionNumber: 0 <pre></pre> Alice has 0 ETH <pre></pre> Bob has 0 ETH"] end subgraph on-chain state ms["<b>AB Multisignature Wallet</b> <pre></pre> Balance: 0 ETH"] end

Messages

After authentication and initializing a connection, channel establishment may begin. All state channels must run the Setup Protocol before any other protocol. As the name suggests, its purpose is to setup the counterfactual state such that later protocols can be executed correctly.

Specifically, the Setup Protocol exchanges a commitment allowing a particular off-chain application to withdraw funds from the multisignature wallet. We call this application instance the Free Balance application, representating the available funds for any new application to be installed into the state channel. The app definition is called IdentityApp.

sequenceDiagram Alice->>+Bob: Setup Bob-->>-Alice: SetupAck

Unlike other protocols, there is no extra message data for the Setup Protocol because the commitment digests are fully determined by the addresses of the participants.

The Setup Message

Field	Description
protocol	"setup"
multisig	The address of the on-chain Alice-Bob multisignature wallet
data	""
fromAddress	The address of Alice
toAddress	The address of Bob
seq	3
signature	Alice's signed commitment digest

The SetupAck Message

Field	Description
protocol	"setup"
multisig	The address of the on-chain Alice-Bob multisignature wallet
data	""
fromAddress	The address of Alice
toAddress	The address of Bob
seq	4
signature	Bob's signed commitment digest

Commitments

Commitment for Setup and SetupAck:

The commitment can be visually represented like:

graph TB subgraph Interpreter interpretOutcomeAndExecuteEffect["interpretOutcomeAndExecuteEffect(outcome, params)"] end subgraph ChallengeRegistry getOutcome["getOutcome(freeBalanceAppIdentityHash)"] end subgraph ConditionalTransactionDelegateTarget executeEffectOfFreeBalance executeEffectOfFreeBalance -->|DELEGATECALL - Pass outcome and params to interpreter| interpretOutcomeAndExecuteEffect executeEffectOfFreeBalance -->|STATICCALL - Fetch outcome for interpreter| getOutcome end subgraph Multisig execTransaction -->|DELEGATECALL - Delegate to delegate target to control funds |executeEffectOfFreeBalance end