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Bitcoin is a stupid base layer. In a native scripting environment, the calculations are stateless, with each transaction being independently validated. This does not incorporate memory for previous events or intermediate results. This limits Bitcoin to simple one-time logic, such as Multisig, Timelocks, or basic inheritance agreements.
The True Bitcoin Layer-2 (L2) network requires stateful calculations in Bitcoin, with Starkware’s new ColliderVM.
The idea is to allow Bitcoin to validate complex calculations across transactions. This was thought to require an upgrade of a new soft fork. While in the early stages of development, ColliderVM is taking part in a growing, reliable L2 bridge architecture that seeks to bypass the current deadlock around new Bitcoin opcodes such as CTV and CAT. No fork is required.
ColliderVM is based on previous ColliderScript ideas from BITVM2 and Starkware to pass data across Bitcoin transactions using Hash-Collision-based puzzles. According to Starkware co-founder Eli Ben-Sasson, this makes it “at least x10,000 more efficient” than Collidersscript.
However, as BITVM creator Robin Linus noted Blockworks, it may not be that impressive as “Colliderscript is practically slow”.
ColliderVM avoids the central fraud proof of BITVM2. This means that operators are not forced to pay withdrawals upfront while waiting for the fraud window to expire. Instead, the calculation is based on validity and is verified directly with Bitcoin.
“Think of this as step 2 of the delivery journey (proof of ZK effectiveness),” Ben Sasson told BlockWorks.
The trade-off is cost. Mishakomarov, creator of Bitcoin Pipe, said: “About 30 hours of the entire Bitcoin network hashrate will have to pay one contract.
Ben Sasson admits that ColliderVM is still expensive and not ready for prime time. “Newly released research shows it works, so it’s not that it’s financially viable,” he said.
However, ColliderVM’s capital efficiency and simplicity could appeal to developers who are unhappy with the complexity of BITVM2 without the need for onlookers or interactive challenge protocols.
Linus himself looks forward to further upgrades to Bitcoin. “CTV is perfect for BITVM,” he said. In particular, he said he would pair it with CSF to simplify bridge logic by “eliminating the assumption of existential integrity.” Meanwhile, ColliderVM avoids the need for CTV completely, but for now it is at the expense of actual feasibility. This can change with the advent of special hardware.
Pipes, on the other hand, represent an alternative approach. This is something Willem Schroé, co-founder of Botanix Labs. In his view, BITVM is “too complicated” and ColliderVM is “great but energy-intensive.” The pipes are “very simple, very clean, but very theoretical and may not work.”
Komarov agrees. “Compared to this hash collision trick, the pipe is much more experimental from a theoretical perspective,” he told BlockWorks. “But when they work, they’re much cheaper.”
Schroé has a strong view on the bridge’s verification space. Regardless of which approach will be production response first, he believes they are doing what is important. They show that users want to act like a contract.
“Bitcoin core doesn’t even think about contracts,” Schlow said. “But the pipes and corridors allow you to show that demand.”
