Leveraging the power of Bitcoins with RSK
Learn how RSK works and how to deploy your smart contracts to it
I'm always interested in what other ways one can use their blockchain and Solidity skills. While many projects are still only in the planning or in testnet status, with Rootstock (RSK) you can transfer mainnet Bitcoins to an EVM sidechain and vice-versa already today. Utilizing the power of the EVM allows you to deploy Solidity contracts and use existing Ethereum infrastructure and tooling around it.
Let's see how to use it...
What is RSK?
RSK is a sidechain for the Bitcoin blockchain with full EVM support. This means you can deploy Solidity contracts here, while leverage the security of Bitcoin mining. Most tools will also have support for the RSK chain given its EVM capability.
All details can be seen in the Whitepaper.
What is the RSK sidechain?
Sidechains generally are EVM-compatible, separate blockchains with their own consensus models. Sidechains are designed to easily allow transfer of value and arbitrary state with the main chain. RSK is special as it's not connecting towards the Ethereum mainnet, but rather the Bitcoin blockchain.
+ allow you to run fully functioning smart contracts
+ value exchange with Bitcoin main chain
- security currently still relies on a set of 15 trusted notaries
How is the sidechain secured?
The sidechain of RSK is run by Bitcoin miners via 'merged mining'. Any Bitcoin miner can choose to additionally become a miner in the RSK network without having to allocate extra resources for the RSK chain. How does that work?
- The miner creates a block for the RSK chain containing all newly added transactions in the RSK chain.
- The miner then hashes this block and creates a valid Bitcoin transaction containing the hash and adds it into the existing new Bitcoin transactions.
- Now the miner creates the final Bitcoin header with this transaction in it.
Now there are three scenarios:
- The new block satisfies the Bitcoin difficulty which will be the least likely. In this case the RSK block hash is simply ignored, but the overhead is tiny as it's just a single additional hash. The transaction fees from the Bitcoin network will go towards the miner.
- The new block satisfies the RSK difficulty, but not the Bitcoin difficulty. In this case only the RSK block will be activated and integrated in the RSK sidechain. The transaction fees from the RSK network will go towards the miner.
- The new block doesn't satisfy any difficulty, so it's just ignored.
As you can see, almost no extra work is required for the miner this way. The difficult part of computing hashes has to be done only once for the Bitcoin and RSK chain at the same time. This incentivizes Bitcoin miners to also mine RSK as it's simply free additional money. As of now the participation rate is very high ranging from 60% to 80%. The higher the more secure the sidechain will be.
How is the transfer between Bitcoin and RSK secured?
The current 2-way peg design in RSK allows to transfer Bitcoins from the Bitcoin blockchain to the RSK chain and vice-versa.
Current Design: Transfers are secured by 15 public and well-known, trusted notaries. Once you lock Bitcoins in the main chain, they will control those funds. Only once you burn the funds in the RSK chain, will the notaries return your funds on the main chain.
The obvious advantage here is that the system is not fully decentralized.
Future Design: In the future RSK may change the design to a so-called drive-chain. In this design the locked funds are solely controlled by the Bitcoin miners. Unlocking funds happens in a voting period. For this to work however, a new OPCODE in Bitcoin would be required and thus a soft fork introducing the new capability. An existing proposal for a BIP (the Bitcoin equivalent of EIP) is here.
Hybrid: This future design could be added in a hybrid model depending on miner participation. If the miner participation is low, keep the current design with notaries. But as participation increases, give more and more power to the miners. Eventually only miners will control the funds.
You can find more details about the two peg design here.
RSK further told me they are about to announce their PowPeg very soon, a new peg system. This will come in the form of a blog post and an accompanying page on our developer portal.... so watch this space!
Existing projects on RSK
But not only that, many projects or forks of those already exist inside RSK. Some highlights include:
- RSK Swap (Uniswap fork)
- Chainlink Integration
- DAI Token via Bridge
How to deploy to RSK
Deploying to the RSK sidechain is very simple. If you're using Truffle, simply add the network configuration like this:
Truffle's built in HDWalletProvider, as well as the bundled Web3Provider, were previously using hard coded values that are OK for Ethereum, but not OK for RSK. This was due to larger block times, the resulting rate limits configured on our public nodes.
You can now override these defaults - to make Truffle work better with RSK.
testnet: {
provider: () => new HDWalletProvider({
mnemonic: {
phrase: testnetSeedPhrase,
},
providerOrUrl: 'https://public-node.testnet.rsk.co/2.0.1/',
// Higher polling interval to check for blocks less frequently
pollingInterval: 15e3,
}),
// Ref: http://developers.rsk.co/rsk/architecture/account-based/#chainid
network_id: 31,
gasPrice: Math.floor(gasPriceTestnet * TESTNET_GAS_MULT),
networkCheckTimeout: 1e6,
timeoutBlocks: 100,
// Higher polling interval to check for blocks less frequently
// during deployment
deploymentPollingInterval: 15e3,
},Without the above, you're likely to run into intermittent failures for truffle migrate, and intermittent warnings when you leave truffle console running.
You'll also need funds in the sidechain of course. For the testnet, just use the available faucet here. For mainnet you need to use the bridge as described below and further use the config:
- provider: () => new HDWalletProvider(mnemonic, 'https://public-node.rsk.co')
- network_id: 30
Be aware that for production services you may not want to rely on a public node, but rather run your own RSK node.
Onboarding users
MetaMask
To interact with the side chain, users need to add the RSK network to their MetaMask. Click on the network selection in MetaMask and then choose 'Custom RPC'. For the current testnet, use the configuration of
- RPC URL:
https://public-node.testnet.rsk.co - ChainID:
31 - Symbol:
tR-BTC - Block Explorer URL:
https://explorer.testnet.rsk.co
For mainnet you can use
- RPC URL:
https://public-node.rsk.co - ChainID:
30 - Symbol:
R-BTC - Block Explorer URL:
https://explorer.rsk.co
Value transfer from and to RSK
1. Getting the native RSK (BTC <-> R-BTC)
To get the native RSK token, you only need to transfer Bitcoins to the bridge address.
- To have a testnet BTC address, start Electrum in testnet mode.
- If you want to try it in the testnet, obtain some testnet BTC via https://testnet-faucet.mempool.co/.
- Now using MyCrypto, choose the RSK Testnet in “More Networks” and navigate to “MyCrypto -> Contracts -> Select Existing Contracts -> “Bridge” -> “getFederationAddress”. This will give you the bridge address for the testnet. You can send BTC to this bridge.
- Your respective RSK EVM key can be generated from the Bitcoin address using the converter tool.
The way back is even easier, just send the (t)R-BTC to the address 0x0000000000000000000000000000000001000006. Done.
2. Moving Ethereum ERC-20 tokens to RSK (e.g. DAI <-> r-DAI)
Since RSK is an EVM compatible chain, it makes sense that they further offer to transfer Ethereum tokens to it. To move a token between RSK chain and Ethereum mainnet, there is a bridging system that is very easy to use. You can use the following services:
- For the mainnet use https://tokenbridge.rsk.co/.
- For the testnet (BTC testnet <-> Kovan testnet) use https://testnet.tokenbridge.rsk.co/.
Future RSK Development
The obvious next step for RSK would be integrating the described drivechain design. However since it's relying on a Bitcoin soft fork, we have no idea when or even if this is will be coming in the future. If you have further details about it, I'd love to hear it and please leave a comment.
Otherwise the team is working on bring meta-transactions to the system:
Have you used RSK before? Maybe even on Mainnet? Let me know in the comments.
Next week we will look at everything one needs to know about ERC-1155, so stay tuned!
Solidity Developer
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How you can design stages in your contract
Closely related to the concept of finite-state machines, this pattern will help you restrict functions in your contract. You will find a lot of situations where it might be useful. Any time a contract should allow function calls only in certain stages. Let's look at an example: contract Pool {...
Web3 1.2.5: Revert reason strings
How to use the new feature
A new Web3 version was just released and it comes with a new feature that should make your life easier. With the latest version 1.2.5, you can now see the the revert reason if you use the new handleRevert option. You can activate it easily by using web3.eth.handleRevert = true . Now when you use...
Gaining back control of the internet
How Ocelot is decentralizing cloud computing
I recently came across an ambitious company that will completely redefine the way we are using the internet. Or rather, the way we are using its underlying infrastructure which ultimately is the internet. While looking at their offering, I also learned how to get anonymous cloud machines, you...
Devcon 5 - Review
Impressions from the conference
I had a lot to catch up on after Devcon. Also things didn't go quite as planned, so please excuse my delayed review! This year's Devcon was certainly stormy with a big typhoon warning already on day 1. Luckily (for us, not the people in Tokyo), it went right past Osaka. Nevertheless, a lot of...
Devcon 5 - Information, Events, Links, Telegram
What you need to know
Devcon 5 is coming up soon and there are already lots of events available, information about Osaka and more. Here is a short overview: Events Events Calendar Events Google Docs Events Kickback Most events are in all three, but if you really want to see all, you will have to look at all three...
Design Pattern Solidity: Off-chain beats on-chain
Why you should do as much as possible off-chain
As you might have realized, Ethereum transactions are anything but cheap. In particular, if you are computing complex things or storing a lot of data. That means sometimes we cannot put all logic inside Solidity. Instead, we can utilize off-chain computations to help us. A very simple example...
Design Pattern Solidity: Initialize Contract after Deployment
How to use the Initializable pattern
There are a few reasons why you might want to initialize a contract after deployment and not directly by passing constructor arguments. But first let's look at an example: contract MyCrowdsale { uint256 rate; function initialize(uint256 _rate) public { rate = _rate; } } What's the advantage over...
Consensys Blockchain Jobs Report
What the current blockchain job market looks like
Consensys published their blockchain jobs report which you can checkout in their Blockchain Developer Job Kit. The most interesting aspects are Blockchain developer jobs have been growing at a rate of 33x of the previous year according to LinkedIns jobs report Typical salary is about...
Provable — Randomness Oracle
How the Oraclize random number generator works
One particularly interesting approach by Provable is the usage of a hardware security device, namely the Ledger Nano S. It uses a trusted execution environment to generate random numbers and provides a Provable Connector Contract as interface. How to use the Provable Randomness Oracle? Use the...
Solidity Design Patterns: Multiply before Dividing
Why the correct order matters!
There has been a lot of progress since the beginning of Ethereum about best practices in Solidity. Unfortunately, I have the feeling that most of the knowledge is within the circle of experienced people and there aren’t that many online resources about it. That is why I would like to start this...
Devcon 5 Applications closing in one week
Devcon 5 Applications closing
Watch out for the Devcon 5 applications. You only have one week left to apply either as Buidler Student Scholarship Press Devcon is by far the biggest and most impressive Ethereum conference in the world. And it's full of developers! I am especially excited about the cool location this year in...
Randomness and the Blockchain
How to achieve secure randomness for Solidity smart contracts?
When we talk about randomness and blockchain, these are really two problems: 1. How to generate randomness in smart contracts? 2. How to produce randomness for proof-of-stake (POS) systems? Or more generally, how to produce trusted randomness in public distributed systems? There is some overlap...