One-way bridge for NFTs (ERC721) from SmartBCH (EVM) to CashTokens on Bitcoin Cash.
To bridge the NFTs the user first sends them to a burn address. Then, the user provides a cashtokens payout address with a proof of burn to the server. The server the re-mint the NFT as CashToken to the provided address.
A subscription monitors all NFT burns of the reapers contract, and writes them to a postgres database. A simple API server exposes the burn & bridging info through several endpoints. when a user provides a cashtokens payout address with a proof of burn to the server, the server validates the proof, re-issues the NFT to the provided address and mark the NFTs as bridged in the database. The matching front-end code can be found in the repo for the reapers website.
Many NFTs can be batch burned together using the Mantra bundle transfer, the NFTs will also be re-issued together to the payout address in one transaction. This makes it easier to follow and check batch bridging on-chain and it saves on gas fees on the SmartBCH side and also on the Bitcoin Cash side.
Because of the public API endpoints anyone can see all the burning and bridging that has taken place. For each bridged NFT there is a signatureProof
which is the signature from the origin address signing the cashtokens receiving address. This proves the bridging destination is the one provided by the user.
By re-issuing the NFTs as they are burned, there never exists more than the maximum supply of NFTs in circulation. Fetching the supply on CashTokens will get you the amount of NFTs that have been bridged.
/
/all
/recent
/signbridging
/address/:originAddress
The home endpoint simply provides the number of nftsBridged
, the all
endpoint provides data of all burned and bridged NFTs, /recent
only provides the data of the latest 20 items.
/signbridging
is the POST endpoint for users to provide their cashtokens payout address together with proof authorizing the bridging to that address.
Lastly, /address/:originAddress
provides all the minting and burning info with a specific originAddress
.
git git@github.com:mr-zwets/reapers-bridge.git
npm install
Example .env
file
SEEDPHRASE=""
DERIVATIONPATH="m/44'/145'/0'/0/0"
NETWORK=""
TOKENID=""
CONTRACTADDR=""
SERVER_URL=""
PGHOST=''
PGUSER=
PGDATABASE=
PGPASSWORD=
PGPORT=5432
npm start
or
tsx bridge.ts