After weeks of debate over Bitcoin drivechains, a similar project to unlock the network’s programming potential is picking up steam.
On Monday, Jameson Lopp — co-founder and CTO of mobile self-custody firm Casa — published a blog post about “Spiderchain,” which he called “another proposal for building 2-way pegged sidechains.”
A sidechain is a separate blockchain that is tied to the main Bitcoin network in some way. They usually use the same native currency—BTC—and can also use Bitcoin’s security guarantees. Sidechains allow Bitcoiners to access many features of their BTC that the main network cannot always provide, such as scalability, programmability, and privacy.
The main difficulty with sidechains, however, is the creation of a “2-way peg” that allows BTC to be safely transferred to the sidechain and back without the need for a centralized middleman.
That’s where the Spiderchaindeveloped by Botanix Labs, began to play.
“Spiderchain works as a Proof of Stake Layer 2 in Bitcoin,” Willem Schroé, founder of Botanix Labs, said Decrypt. “You put Bitcoin on Bitcoin on decentralized multisigs.”
The entities that manage decentralized multisigs are called “orchestrators,” which run a Bitcoin node and a Spiderchain node. For each request to transfer BTC to Spiderchain, a new multisig is created controlled by a random subset of 100 participants within the staker set.
In many ways, Spiderchain works like Ethereum: it is Ethereum Virtual Machine-compatible, has 12-second block times, and uses a proof of stake consensus mechanism to secure the network, where the nodes of orchestra must stake in BTC to participate.
Its EVM is also “fully equivalent,” which means that existing Ethereum dapps can easily be transferred to the developers’ network. But unlike Ethereum, Schroé said that a malicious majority of orchestrators would still not conspire to steal users’ BTC.
“The design is possible with the current Bitcoin core, so no soft fork or upgrade is required,” said Schroé. This distinguishes Spiderchain from Paul Sztorc’s drivechain proposalwhich requires changing the Bitcoin code that users and miners are currently running.
Drivechain was introduced as BIP 300 and BIP 301 back in 2015, and is still widely accepted for implementation by Bitcoiners.
Drivechains effectively put control of targeted BTC in the hands of Bitcoin miners, but allow any number of sidechains with any number of assets to be created. It also directly inherits Bitcoin’s security by integrating mining, which piggybacks on the massive proof-of-work security of the main network.
When asked about Spiderchains, Sztorc said they were “too complicated” compared to his proposal.
“I also think the whole “there needs to be a change in Bitcoin” is pure superstition, unfortunately,” he added. “People think it means ‘the network needs to upgrade, but in reality it’s like asking users to install an app on their phone.
In Lopp’s Monday blog post, the CTO cited the nearly decade-old Rootstock proposal, and pointed out some of Spiderchain’s technical weaknesses. Among them is the risk that its BTC peg is “broken” if the main Bitcoin blockchain experiences a reorg which is longer than five blocks, due to the system by which Spiderchain orchestrations are determined.
“It’s unlikely to be catastrophic because of how the funds are spread across multiple multi-sig wallets,” he said.
Schroé also admitted that in the early stages of the network, Spiderchain will be centralized until more users log in to stake their BTC. “We have to start centralized in the sense that initially we have to allow staking,” he said.