Server node for the Cosmic Bridge application. Manages tracking payments/balance on the Cosmos chain and bundled scheduled payouts on the Bitcoin mainnet.
For architectural overview, see here: https://docs.google.com/presentation/d/1-8MP2yRhTy7D1YDUiauJoJ1g_ppXQbRpk0YTQ0ZFEzw/edit#slide=id.g3772f84a12_0_18
The Cosmic Bridge server node serves as a validator/facilitator of transactions.
The funds are stored in a multi-sig wallet ; any payment needs to be properly signed by a subset of the validators.
In order to participate in the Cosmic Bridge network, a user should send bitcoin to a particular payment zone address - a specific wallet on the Bitcoin blockchain. Once bitcoin has been received, users can micro-transact bitcoin on a Cosmos chain (this chain is the "payment zone"). The balances can be paid out on-demand on the Bitcoin chain, vastly reducing the number of required transactions (and hence the transaction fees paid) as the number of transactions on the off-chain network increases.
The end result is that users save transaction fees by bundling up transactions on the bitcoin network while still enjoying transparency and safety. In return, the complete trustlessness of the Bitcoin chain is exchanged with a degree of trust in the validator set of the payment zone. This compromise can be acceptable for many potential uses, such as large volumes of micropayments.
Cosmic Bridge can be used for any application that requires cheap, fast and auditable settlement of Bitcoin transactions, assuming on-demand Bitcoin-chain settlement is acceptable. Payment Zones can be free for anyone to join, or limited to certain parties. In theory, the longer users maintain and use the balances on the cosmos bridge network, the more optimizations can be done in terms of payment merging. Some potential applications:
- Bitcoin micropayments
- Dark pools of BTC liquidity between exchanges or large traders
- A merchant network supporting free bitcoin payments for participating merchants
Right now the system does not involve stake mechanics, since the idea is to rely on a trusted, well-known set of validators. In the future, staking mechanics, based on BTC staking or a native token, could be implemented easily as Cosmos supports them.
Connecting to the payment zone is done via the Tendermint API. Transactions have a 'command' field that indicates the type of transaction. Following are examples for possible transactions:
-
Deposit - process a deposit made on the Bitcoin chain to the Payment Zone master address, so the bitcoin can be used for payments in the Cosmic Bridge Payment Zone:
curl http://localhost:PORT/txs -d '{"command": "deposit", "txHash": "<Transaction ID of the Bitcoin transaction>"}' -
Pay - perform a payment within the payment zone.
For instance, to perform a microtransaction of 1 satoshi from ADDRESS1 to ADDRESS2:
curl http://localhost:PORT/txs -d '{"command": "pay", "amount": 1, "from": "ADDRESS1", "to": "ADDRESS2", "signature": "<XXX - see below>"}'The signature is a proof of ownership. It should be the transaction ID of one of the deposit transactions to the 'from' address, signed with that address' private key. Note that the depositing Bitcoin addresses are used for transaction addressing within the Payment Zone (e.g. on the Cosmos chain) as well - there's no need for "new" or Cosmic-Bridge-specific addresses.
To check the balance of ADDRESS1, just do:
curl http://localhost:PORT/state
Which returns a JSON dictionary, and then use the key 'balances' and then key 'ADDRESS1' to get the balance for ADDRESS1
Examine the config files first.
If you're creating a new payment zone (or app), you should create a new multisig wallet for the master address. This can be done from the src/multisig folder by running the create_multisig.js script.
Configuration files are loaded from the /config sub-directory. The file default.json contains development configuration values, while production.json contains production (mainnet) configuration values.
WARNING: This is a work-in-progress towards a MVP. Do NOT, under any circumstanes, use this in production. The current implementation has MULTIPLE, VERY OBVIOUS security flaws. You have been warned!!!
To start a Cosmic Bridge node, run the following command:
npm install && npm start
bcoin is required on every validator node in order to test transactions for correctness and submit transactions to the bitcoin network. Indexing of transactions and addresses is required in order to support the queries done by the validator nodes. Set your /.bcoin/bcoin.conf file with new values like the following (for testnet):
network: testnet prefix: ~/.bcoin api-key: hunter2 prune: false index-tx: true index-address: true
or use the following command:
bcoin --http-host=0.0.0.0 --api-key hunter2 --network=testnet --daemon --index-tx --index-address
removing the network flag for mainnet deployments. Note that the index-tx and index-address flags are required by the node in order to perform historic queries on the master address.
npm test
For a mainnet app, you'll want to define a set of validators as well as a genesis block so the app doesn't create a new GCI each time the app is run. This is documented further in the initial state of lotion_app.js.
- https://lotionjs.com/
- http://bcoin.io/guides/multisig-tx.html
- http://bitcoinfaucet.uo1.net/send.php
- https://github.com/bitpay/bitcore-message
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