Core
This submodule assists with handling key business logic functions and processes.
Overview
One may conceive of MACI as a state machine with 1) data and 2) functions which transform said data. This makes it easier to reason about the system, write tests, and implement functionality. It also allows us to implement the smart contracts in discrete components which are easy to test.
To this end, this submodule exposes a MaciState
class and a Poll
class.
Developers should instantiate objects from these classes to test MACI. For
instance, MACI.test.ts
creates a
MaciState
object and every time it interacts with the MACI smart contract, it
mirrors said interaction on the MaciState
and Poll
. As such, the developer
can then use their helper functions like maciState.signUp()
,
poll.publishMessage
, poll.processMessages()
, and poll.tallyVotes()
to
step through the various stages of the MACI flow.
MaciState
Key functions
signUp
Accepts a user's public key and creates a new state leaf and ballot leaf.
In testing, whenever a test suite submits a signUp()
transaction, it should
call maciState.signUp()
as well, so that the off-chain representation of MACI
is kept up to date.
In production, genMaciStateFromContract()
in
genMaciState.ts
uses this function when it
scans a MACI contract's event log for signups, so as to bring its MaciState
instance up to date.
deployPoll
Creates a new Poll
. This should be done whenever the MACI contract's
deployPoll()
function is called.
Helper functions
copy
A function that deep-copies an object.
Key data structures
stateTree
stateTree
is a quinary Merkle tree, chosen over a binary tree due to the gas and circuit constraints associated with the Poseidon hash function (details here). Each leaf in this tree represents a participant's public key, their voice credit balance and the block timestamp at which they signed up. The tree features a configurable depth and an arity of five, with insertions starting at index 1. The zeroth leaf is reserved as a security measure against denial-of-service attacks.
Poll
A Poll
is an off-chain representation of a Poll. In testing, Poll
instances
should mirror their on-chain counterparts.
Key functions
publishMessage
Publishes a message by updating the message tree and message accumulation queue.
processMessages
Processes a batch of messages and returns the inputs to the processMessages
circuit which can be used to prove correct execution.
tallyVotes
Tallies a batch of votes and returns the inputs to the tallyVotes
circuit which can be used to prove correct execution.
Helper functions
copy
Deep-copies and returns this object.
Key data structures
messageTree
messageTree
is also a quinary Merkle tree. Each message in this tree represents an encrypted command, such as a user casting a vote in a poll or changing their public key.
Testing
For more details about testing please refer to the tests documentation.
Directory Structure
ts/
: The home for our core classes,MaciState
andPoll
ts/utls/
: Contains supporting utilitiests/__tests__/
: A dedicated test suite directory