Aleph Zero MOST^* (Guardian) Bridge

Bring your assets to Aleph Zero and benefit from its scalable privacy-enhancing ecosystem.

^{*'bridge' in Slavic languages.}

Contents

• azero - Aleph Zero contracts
  • azero/contracts/most - the main bridge contract
  • azero/contracts/gas-price-oracle - a contract for informing the guardians about Ethereum gas prices
  • azero/contracts/token - a PSP22 token implementation for the tokens created by the bridge
• eth - Ethereum contracts
  • eth/contracts/Most.sol - the main bridge contract
  • eth/contracts/Governance.sol - a contract for making governance decisions about the bridge contracts on Ethereum
  • eth/contracts/WETH9.sol - a wrapped ethereum implementation for testing purposes
  • eth/contract/Token.sol - an ERC20 token implementation for testing purposes
• relayer - the component doing the actual bridging between the chains

Prerequisites

1. Have docker and docker-compose (1.29.2)
2. Have cargo-contract (3.2.0) installed:

cargo install cargo-contract --vers 3.2.0

Testing the contracts

Solidity contracts

To run the tests for the Solidity Most.sol contract, run:

make test-solidity

It will run the tests using the Hardhat framework. Alternatively, you can run the tests directly from the selected file in the eth directory, for example:

cd eth
npx hardhat test test/Most.js

Ink! contracts

Unit tests

To run the unit tests for the ink! contracts, run:

make test-ink-unit

These will allow you to test the contracts in isolation, without the need for running a blockchain node in the background.

DRink! tests

To run DRink! based tests, which allow for testing interactions between multiple contracts without the need to run a node, run:

make drink-tests

DRink! tests are located in azero/contracts/drink-tests/.

ink_e2e tests

To run the end-to-end tests for the ink! most contracts, run (requires docker-compose 1.29.2):

make test-ink-e2e

These tests are located at azero/contracts/tests.

Running the local development environment

To run a local development environment, run:

make bridge

This will start a local development environment with the following components:

• Aleph Zero Development chain
• Ethereum PoS Development chain
• Bridge contracts deployed on both chains
• Redis instance
• Relayer process

Running local development chains

To run the development chain without deploying the contracts or running the relayer, run:

make devnet-eth

or

make devnet-azero

Running a relayer with a signer locally

First, run the signer:

cd relayer
RELAYER_ID=1 scripts/run_signer.sh

The signer will output the CID on which it is running, but you should also be able to just use 2 (meaning host) as the CID.

Next, run the relayer, passing the signer CID to connect to:

# in most/relayer
SIGNER_CID=2 scripts/run_relayer.sh

Cleaning up

To stop the networks (and redis) and clean up:

make clean

Check eth nodes connectivity

get a shell into running container:

docker exec -it eth_bootnode "geth attach /root/.ethereum/geth.ipc"

attach console to the geth process:

geth attach /root/.ethereum/geth.ipc

Check the connected peers, confirm these are the correct nodes:

net.peerCount
admin.peers

Deploying contracts

To deploy the contracts on the EVM chain:

make deploy-eth

This command will deploy the contracts and print out the contract addresses.

Now, open a Hardhat console:

cd eth && npx hardhat console --network development

Interact with the deployed contracts instance:

let Most = await ethers.getContractFactory("Most")
let most = Most.attach("insert contract address here")
let accounts = await ethers.getSigners();

await most.isGuardian(accounts[0])
await most.isGuardian(accounts[1])

To deploy the contracts on the Aleph Zero chain:

make deploy-azero

Running the relayer processes

make run-relayers

Verifying deployed contracts against source code

Given a deployed (by us) Aleph Zero contract with some code hash C it's possible to check that the contract has been produced from a certain version of the source code in this repo (say a given commit). To do so:

1. git checkout $COMMIT
2. make print-azero-codehashes
3. Find the contract in question in the list and ensure that the printed code hash is the same as C

The contracts will be deployed using the same docker image as the one used for this procedure, which smooths out indeterminism in ink! contract compilation.

Verifying deployed contracts on etherscan

Given a deployed Ethereum contract address it's possible to post verified sources to etherscan and sourcify. You will need an API key for etherscan - can be obtained at https://etherscan.io/myapikey if you have an account. To do so:

1. git checkout $COMMIT - where $COMMIT is the commit from which the contract has been deployed
2. cd eth
3. ETHERSCAN_API_KEY=[YOUR API KEY] npx hardhat verify [CONTRACT ADDRESS] [CONSTRUCTOR ARGS]

For example, if you deploy Token.sol to the sepolia testnet like so:

const usdt = await Token.deploy(
  "12000000000000000000000000",
  "Tether",
  "USDT",
);

and the address is 0xbd737D2061ed3b24C95FA88566Ad896c9Fcc84b0, then you would post verified sources like so:

ETHERSCAN_API_KEY=[YOUR API KEY] npx hardhat --network sepolia verify "0xbd737D2061ed3b24C95FA88566Ad896c9Fcc84b0" \
  "12000000000000000000000000" "Tether" "USDT"

Decoding a contract call on ethereum

Assuming a contract verified on etherscan, there's a convenience script to decode a call to that contract. Just call:

NETWORK=[NETWORK NAME] CALL=[CALL DATA] CONTRACT=[CONTRACT ADDRESS] make decode-eth

Valid values for NETWORK are mainnet (default), sepolia, and goerli.

For example:

NETWORK=sepolia  \
  CALL=0x095ea7b30000000000000000000000005a344a8721d743393847c17613dd78c7776b271400000000000000000000000000000000000000000000000000000000000004d2 \
  CONTRACT=0x5a344a8721d743393847C17613dd78C7776b2714 \
  make decode-eth

gives:

Contract: Token
Method: approve(address,uint256)
Arguments: Result(2) [ '0x5a344a8721d743393847C17613dd78C7776b2714', 1234n ]

Documentation

Additional documentation is written in orgmode, diagrams are written using plantuml.

Orgmode is suported by VSCode, Emacs and vim.

Diagrams

In order to render the diagrams:

java -jar plantuml.jar azero_eth_components.iuml eth_azero_components.iuml

There are various online editors for plantuml that can render the format, e.g.:

• plantuml-previewer

In Emacs you can pass the path to the plantuml executable in the orgmode config:

(setq org-plantuml-jar-path
      (expand-file-name "/path/to/plantuml.jar"))

Then you can use:

C-c C-e l p

to render the whole document and evaluate plantuml code blocks (this will produce png files).

Acknowledgments

This project includes code from the following MIT-licensed project:

• pancake-smart-contracts