With the Bitcoin community recently distracted by the reignited drivechain debate, Casa CTO Jameson Lopp argues that the Botanix EVM Layer 2 protocol’s proposal to link bitcoin to its Spiderchain sidechain has been overlooked.
While the drivechain-native, merge-mined sidechain mechanism for Bitcoin would require a controversial fork, Spiderchain could be implemented today without requiring any changes to the Bitcoin base layer, Lopp said in his last blog post.
Sidechains are secondary blockchains that run parallel to the main blockchain, allowing the transfer of assets between the two chains. The challenge is to do this in a decentralized way.
Botanix Labs recently published a white paper for the proposed Botanix Ethereum Virtual Machine-compatible Layer 2 protocol and Spiderchain sidechain solution. While the software isn’t live yet, Lopp said Spiderchain makes sense at a high level, but it remains to be seen whether it can withstand real edge cases and adversarial conditions.
Why Spiderchain?
Ethereum’s DeFi boom has left Bitcoin somewhat in the shadows, especially when you consider the total value contained in their respective second tiers, Botanix argues in the whitepaper. Botanix EVM aims to bridge this gap by introducing a second layer on Bitcoin with full Ethereum Virtual Machine compatibility. This means developers can leverage the vast array of Ethereum smart contracts while maintaining the security of Bitcoin’s base layer via the Spiderchain sidechain. Synthetic BTC acts as the native currency for Botanix EVM, pegged 1:1 to bitcoin on Spiderchain.
Casa’s CTO noted that detractors said Bitcoin sidechains are useless, with the oldest and most notable, Liquid and Rootstock, struggling to gain significant adoption. However, Lopp argues that continued research into two-way permissionless pegging mechanisms is a worthwhile pursuit, especially as centralized solutions like wrapped BTC have seen strong demand, with more than 150,000 BTC ($4 billion) deposited with a third-party custodian to spend bitcoin . linked tokens on Ethereum.
The Ethereum Foundation’s vision for scalability includes multiple layers of EVM-compatible chains, with the Ethereum base layer providing settlement. However, Lopp argues that Ethereum still faces centralization issues, with Botanix arguing that Bitcoin provides a more suitable foundation on which to build these layers with its high degree of immutability and evidence of job security.
How does Spiderchain work?
Spiderchain works using a series of multisig wallets managed by entities called Orchestrators, Lopp explains. Users deposit bitcoin collateral into a multisig wallet as a stake to run an Orchestrator, which is reduced in the event of malicious activity. These Orchestrators operate a Bitcoin node, a Botanix EVM node, and a Spiderchain node, ensuring the integrity of peg-ins and peg-outs and verifying that other Orchestrators are trading fairly.
Peg-ins result in the creation of a new multisig wallet managed by a random subset of active Orchestrators, with one Orchestrator chosen to manage each epoch (one Bitcoin block). This management of funds by dynamic stakers contrasts with the static consortium model of federated multisig sidechains and the dynamic miner signing model of drivechains, Lopp added.
Botanix uses a Proof-of-Stake consensus model, leveraging Bitcoin’s Proof-of-Work system to offset potential centralization vulnerabilities, Lopp said, adding that the security model is robust provided a majority of Orchestrators acts honestly. However, it also means that stakers receive no base compensation and can only collect transaction fees.
The challenges of Spiderchain
Although Spiderchain offers an interesting solution, it is not without problems, Lopp emphasizes. Questions arise around UTXO management, Orchestrator reliability, and potential attack vectors. If someone were to stake more than 50% of the funds linked to the network, a Spiderchain multisig contained an adversarial quorum of 33%, or if there was a significant Bitcoin reorganization, the security model could fail and the coupling could break, Lopp warned. Furthermore, the cost and complexity of launching such sidechains remain a concern.
However, to prevent silent malicious majority attacks, Spiderchain plans to launch in several phases, with the first phase consisting of centralized, Botanix-controlled Orchestrators, which will become more decentralized over time.
What’s next?
After a decade of research into permissionless sidechain pegging, Lopp argues that there are only two viable options: federated models or a pool of pegged bitcoin.
Federated sidechains distribute trust among many reputable entities. Linked pools in drivechains create incentives for miners to manage bitcoin, while Spiderchain pools incentivize stakers. Each model has its own tradeoffs, Lopp added. But ultimately the test will come from performance under real-world conditions.