xcat

Protocol and api for doing cross chain atomic trades between Stellar and Ethereum.

Protocol

Stellar XLM <-> Ethereum ETH

• protocol_stellar_xlm_to_ethereum_eth.md
• protocol-scenario1.js - script that walks through scenario 1 of the protocol

Stellar Asset <-> Ethereum ERC20 Token

• protocol_stellar_asset_to_ethereum_erc20.md

Progress

Native Token Swap (XLM <-> ETH)

• Protocol API Scenario 1 (Stellar side initiated)
• Protocol API Scenario 2 (Ethereum side initiated)
• Built in communication channel (Telehash Links?)

The protocol for trades initiated from the Stellar side is working as demonstrated by this script which exercises both parties along the path of least resistance. More testing is required around refunds and edge cases.

Communication would ideally be done by the tool over some channel rather then having users manually send each other data (see last todo item above). These 2 pieces require manual sharing:

• initial trade.json and trade.json.sig signature (intiater sends after running 'new', counterparty run 'verifysig' and 'import' commands)
• refund tx envelope (party 2 sends to the initiater, initiater puts it in the trade.json file and runs 'status' to continue with the trade)

These pieces can be found by scanning the ledgers and so don't require communication:

• Ethereum HTLC contract id
• hash(x) preimage (after submission)
• deposit and withdraw transactions on both sides

Asset to Token Swap (Asset <-> ERC20)

• TODO!

Trade.json

Trades are defined by a trade.json file conforming to the JSON schema here.

Example:

{
  "timelock": 1505729032,
  "commitment":
    "22bf0b3d38d2bec7226eeafd6571cdd452d34a79fb4e72f98e246d372c6a9855",
  "stellar": {
    "token": "XLM",
    "amount": 2000.0,
    "depositor": "GADU5GS223ZOY7LRWDE5IQBGMCNI523FCF5CFP2KPMMU3TKLJ7IPHEJU",
    "withdrawer": "GD3BNTEXZF7IG4OSWDJMCZ4V6N4I6XGEWO5Y6P3FYAZ24ARF2DWV2P3L"
  },
  "ethereum": {
    "token": "ETH",
    "amount": 1.0,
    "depositor": "0x7ee7d41559284957f1cd6bd14a658bf985d87ad0",
    "withdrawer": "0xfc80237acff828e5a69ba27ec506c2296dab2f68"
  }
}

Develop

Start Stellar private network

docker run -it --rm --name horizon-integrationnet -p 8000:8000 zulucrypto/stellar-integration-test-network

Start Ethereum local network

PHRASE="end staff push admit delay abandon ability nurse renew alert stomach jazz"
docker run --rm -it -p 8545:8545 chatch/ethereumjs-testrpc:4.1.3 -m "$PHRASE" $@

NOTE: PHRASE is important as the integration tests expect specific accounts to exist.

Deploy HashedTimelock smart contract

git clone https://github.com/chatch/hashed-timelock-contract-ethereum
npm i -g truffle
truffle migrate

Run tests

npm run test

Run integration test

npm run test-protocol