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LeapDAO Bridge implementation



Getting started

yarn test 

Deploying contracts

All the commands support any truffle options like --network or --reset.

Deploying on Rinkeby and Mainnet

To deploy on Rinkeby and Mainnet, make sure to specify your Infura project ID and mnemonic in the .env file. Alternatively, you can change truffle-config.js to use other provider of your choice.

Contracts customization

Contract may be customized via ENV variables:

ENV variable Description Default value
PROPOSAL_TIME Governance proposal cool-off time (in seconds) 1209600 (14 days)
EXIT_STAKE Exit stake (in Wei) 100000000000000000
EXIT_DURATION Exit duration (in seconds) 604800 (7 days)
DEPLOYED_TOKEN Token to be configured in vault
EPOCH_LENGTH Number of initial slots for validators 2
PARENT_BLOCK_INTERVAL Number of Ethereum blocks between Plasma periods 2
TAX_RATE Initial tax rate (0 - 1000 equals 0% - 100%) 50
POA_REWARD Reward rate before supply of 7 million reached 778000000000000000000
GOV_OWNER Owner address of the MinGov.sol contract, should be set to seed initial token supply.

E.g. PROPOSAL_TIME=600 EXIT_DURATION=180 yarn deploy deploys plasma contract with 3 minutes exit duration governed by MinGov with 10 minutes proposal time.

Deploy everything

yarn deploy

This will deploy deploy token, plasma and governance contracts.

Deploy only plasma and governance contracts (reusing token)

yarn deploy:plasma

Good things to know

slotId in MinGov.setSlot is encoded like this:

First 20 bytes last 12 bytes
address(OperatorProxy) slotId


In this repository are the solidity smart contracts implementing LeapDAO's plasma leap.

There are 3 smart contracts that get deployed:

  • Bridge

    The bridge is responsible for storing the period chain. It is the source of truth for the plasma chain.

  • Operator

    The operator is the contract that is responsible for submitting new periods to the bridge.

  • ExitHandler

    This contract is responsible for user funds. Explained in more detail below.


The ExitHandler is actually the final contract in an inheritance chain that goes as follows:

  • Vault

    The vault defines what types of assets are allowed on the plasma chain and is responsible for registration of these assets.

  • DepositHandler

    The deposit handler is in general responsible for how funds get onto the plasma chain.

  • ExitHandler

    The exit handler is in general responsible for how funds leave the plasma chain.

Inheritance chain


Project source files are made available under the terms of the Mozilla Public License (MPLv2). See individual files for details.