The life of a Transaction

What is a transaction

• A Transaction Consists of inputs and outputs
  • Each input and output belongs to a certain module (e.g. Mint, Wallet, …)
  • All inputs have to add up to the same sum as all outputs
• Also contains a signature
  • Each input has an associated secret/public key pair
  • The signature is a MuSig2 multi signature with all these input keys signing the entire transaction

pub struct Transaction {
    pub inputs: Vec<Input>,
    pub outputs: Vec<Output>,
    pub signature: Option<schnorr::Signature>,
}
…
pub enum Input {
    Mint(<minimint_mint::Mint as FederationModule>::TxInput),
    Wallet(<minimint_wallet::Wallet as FederationModule>::TxInput),
    LN(<minimint_ln::LightningModule as FederationModule>::TxInput),
}

Transaction Creation

• One client module for each federation module
• There are specialized user and gateway clients that use these to construct transactions
• E.g. deposit

Transaction processing

• Submit transaction, first validation
• Save to DB
• Generate consensus proposal with all transactions submitted in the meantime
• Propose to HBBFT
• Process all transactions that were agreed on
• Each input and output are processed by its respective module, e.g. for the Mint module
• Some operations need a second round to submit signature shares, they are submitted via per-module consensus items (see also Generate consensus proposal)
• These are also processed by their respective module

Modules

• For more details, look at the docs, they are great (at least for modules)!