An ERC20 <-> Substrate token swap

For a given ETH wallet:

Transfer a given balance to a new wallet address that belongs to the same holder in a substrate-based parachain.

Architecture

 ┌──────────────┐                                              ┌────────────────────┐
 │              │                                              │                    │
 │  ETH Wallet  │                                              │ Parachain Wallet   │
 │              │                                              │                    │
 └───────┬──────┘                                              └───────▲────────────┘
         │                                                             │
         │      Transfer                                               │   Mint Tokens
 ┌───────▼──────┐ Req    ┌───────────────────────────┐ Mint RPC┌───────┴────────────┐
 │              ├───────►│                           ├────────►│                    │
 │ JURBridge.sol│        │    Node.js Relay (Bridge) │         │  JURToken.rs       │
 │              │◄───────┤                           │◄────────┤                    │
 └──────────────┘        └───────────────────────────┘ ACK     └────────────────────┘
  Lock Token                    Register  Users

Directories

• jur-token/ Contains the solidity contracts used to represent the original VIP-180 token and the bridge contract that holds funds at the contract address when a transfer is requested.
• jurbridge/ Holds the ink!contract used to mint new ERC20 compliant tokens on the parachain.
• relay-server/ Contains the npm server used to operate the off-chain relay.

Testing

---

Dependencies

Please make sure you have the following installed:

• ganache
• truffle
• substrate-contracts-node
• Rust tooling
• npm

Start ganache

ganache -m "buffalo learn average iron fly rocket bargain diet fly arrest thank keen"

Compile and migrate solidity contracts

cd jur-token/
rm -rf build/
truffle compile
truffle migrate

Start the contracts node

substrate-contracts-node --dev

Build the smart contract

cd jurbridge
cargo +nightly contract build

Connect to the subtrate node and upload the contract

1. Go to the polkadot dashboard
2. Upload the contract found at ./jurbridge/target/ink/jurbridge.contract.
3. Copy the contract public address to the PARACHAIN_ADDRESS variable in ./relay-server/-env.

Test an end to end transfer

Testing using mocha:

cd relay-server
npm test

Debugger listening on ws://127.0.0.1:9229/6b458a7f-0c17-469a-85c0-28974e8017ed
For help, see: https://nodejs.org/en/docs/inspector


  User register test
    ✔ tests that a user can successfully register

  User already exists test
    ✔ tests registration should fail if user already exists

  ETH to Substrate test
2023-02-04 15:17:24.027	INFO	/src/services/ethRelay.ts:70	Getting gas price and nonce
2023-02-04 15:17:24.031	INFO	/src/services/ethRelay.ts:74	Sending signed transaction
2023-02-04 15:17:24.047	INFO	/src/services/ethRelay.ts:120	Setting approval on token contract
2023-02-04 15:17:24.057	INFO	/src/services/ethRelay.ts:137	Locking funds on bridge contract
2023-02-04 15:17:24.069	INFO	/src/services/parachainRelay.ts:71	Connecting to substrate endpoint
2023-02-04 15:17:24.111	INFO	/src/services/parachainRelay.ts:82	Querying substrate contract for refTime and proofSize
2023-02-04 15:17:24.125	INFO	/src/services/parachainRelay.ts:96	Executing transfer to substrate
    ✔ tests that funds have been successfully transferred from eth to substrate (307ms)


  3 passing (341ms)

See relay-server/tests/integration.ts for example usage

Testing using REST

Start the server:

cd relay-server/
npm run start

You can query the relay server using rest endpoints as follows:

curl -XPOST http://localhost:8080/register -d '{"eth":"0x7FB215F9Eb718e0757182Ae9a3A596Bcf0b1c40d", "uri":"//Alice"}' -H "Content-Type: application/json"

curl -XPOST http://localhost:8080/add-funds -d '{"eth":"0x7FB215F9Eb718e0757182Ae9a3A596Bcf0b1c40d", "amount": 10000000}' -H "Content-Type: application/json"

curl -XPOST http://localhost:8080/transfer -d '{"eth":"0x7FB215F9Eb718e0757182Ae9a3A596Bcf0b1c40d", "ethPriv": "0x9fed92bcfe9c078c15d3548e5763c17dde60715ce5fdca5c70f2bfd14b08a4e4", "amount": 1000}' -H "Content-Type: application/json"

Please see the plan and notes for more details.