Hello, Rootstock Swaps! 👋
Today, we are thrilled to publicly launch our Rootstock <> Lightning bridge. It lets anyone explore Rootstock with ease and enables exciting use cases on Lightning ⚡
Boltz has a bold vision: to become the go-to bridge that connects Bitcoin’s layers. But with the recent surge of “Bitcoin Layers” - which are the interesting ones?
For Boltz, we established the following framework1:
The layer’s Bitcoin token needs to be verifiably backed 1:1 by mainchain Bitcoin
The layer needs to use its Bitcoin token to pay for network fees, not some alternative token
The layer needs to show meaningful organic growth of economic activity
We are thrilled to launch our integration with Rootstock today, a true OG among Bitcoin’s layers that checks all the boxes ✅
A Primer on Rootstock
Rootstock is the first and longest-running Bitcoin sidechain. Operating since January 2018, it combines the security of Bitcoin's proof of work via merged mining (currently >50% of the Bitcoin hashrate is participating in Rootstock), with EVM smart contract capabilities. Similar to the Liquid sidechain, which is already available on Boltz, it leverages a federated multi-sig to secure its peg between Rootstock Bitcoin (“RBTC”) and mainchain Bitcoin.
From Boltz’s perspective, the notable differences in comparison with Liquid are:
Account vs UTXO model
Block production on Rootstock is separated from the Bitcoin peg’s multi-sig entities and is secured by Bitcoin miners via merged mining; on Liquid both are done by the same entities called “Functionaries”
Block time is ~30s compared to 60s on Liquid
Rootstock’s PowPeg allows anyone to natively peg-out, no special keys required like on Liquid
The account model on Rootstock offers less transactional privacy and does not natively allow for advanced features like Confidential Transactions on Liquid
To sum it up, Liquid and Rootstock complement each other and were created with different goals in mind. While Rootstock focuses to address the desire for advanced programmability in the Bitcoin ecosystem, Liquid focuses on its transactional and advanced asset-issuance capabilities.
Rootstock boasts a vast ecosystem of decentralized applications and open finance services that let you lend, borrow, trade, and earn interest on your Bitcoin.
Finally, Rootstock’s Co-Founder and Chief Scientist, Sergio Lerner, is spearheading BitVMX, a BitVM-inspired implementation to enable a trust-minimized bridge between the Bitcoin mainchain and Rootstock sidechain using ZK proofs.
What can I do with Rootstock Swaps?
Rootstock Swaps allow anyone to explore financial applications on Rootstock easily and quickly using the Lightning Network. Lightning is especially suited for low-value transfers and fast settlement with instant transaction finality; these characteristics have helped it establish itself as the common language between Bitcoin layers.
Starting today, users can move their Satoshis from Lightning to Rootstock using our Web App at boltz.exchange and start exploring the Rootstock ecosystem.
Here are some of the financial applications available on Rootstock:
Money On Chain: Money On Chain (MOC) is the stablecoin protocol that issues Dollar On Chain (DOC), the only 100% Bitcoin-backed stablecoin.
Sovryn: Sovryn is a decentralized platform for Bitcoin trading and lending.
Tropykus: Savings and loans in dollars for Latin America.
Sushi Swap: Sushi Swap is a community-driven decentralized exchange (DEX) for traders and liquidity providers.
An overview of Rootstock’s ecosystem is available here. Rootstock has shown resilient growth in recent months with new partnerships and increasing activity (1, 2).
One aspect we're especially excited about is the new use cases Rootstock enables in combination with Lightning leveraging its Turing-complete programming capabilities.
One problem we believe Rootstock could be the solution to, is to enable non-custodial Lightning Prisms. In short, a Lightning Prism splits one incoming payment into two or more payments to different receivers, e.g. to distribute a payment for an article behind a paywall not only to the author, but also to all authors of content that was re-used. The problem with the current solution based on lightning addresses is that it’s inherently custodial and additionally exposes the prisms to regulatory crackdowns. Rootstock could solve the custody dilemma by letting a prism smart contract on Rootstock handle the payment split. This is currently just an idea, we didn’t work on any technical implementation and there might be technical issues that might make this infeasible. Anyhow, it is just one idea; the design space on Rootstock is virtually endless. 🚀
Implementation Highlights
Rootstock Swaps leverage the same HTLC-based atomic swap principle as all other swaps on Boltz. All swap contract code can be found here and is verified on Rootstock, see e.g. here the current version of the RBTC swap contract.
When starting our integration earlier this year, we faced a deal-breaker problem: users needed RBTC in order to receive RBTC from a swap in order to pay for gas of their claim transactions. This strongly conflicted with our vision to build a tool to onboard new users to Rootstock - users that did not posses RBTC yet.
RIF Relay to the rescue! In the past months, we worked with the RIF Relay team to add support for so-called meta transactions (sometimes also called gasless transactions). Meta transactions via RIF Relay allow Boltz users to sign instructions for RIF Relay to broadcast a swap claim without directly paying for gas. Instead, users pay RIF Relay using the incoming RBTC from their swap for broadcasting the transaction on their behalf. The best part is that the user doesn’t need to worry about this, as the Boltz Web App checks at swap creation if the user has enough RBTC to pay for gas in their wallet. If not, it automatically uses a meta transaction via RIF Relay.
We are also quite proud of the new hardware wallet integration in our Web App for Rootstock swaps. It allows you to directly swap to and from your Ledger and Trezor devices 🙌
What’s Next
Enable Chain Swaps between Rootstock and Liquid/Bitcoin.
Native integrations with projects on Rootstock, like Money On Chain.
Bug fixes and Improvements based on user feedback.
This is what we consider a Bitcoin Layer for integration into Boltz; we agree strongly with the strict definition of a Bitcoin Layer 2 as requiring unilateral exit. More here.