Bitcoin may have passed a revolutionary technical milestone this week—one developers say will let them upgrade the network without needing to fork its code.

Coders at BitcoinOS claim they have successfully verified a zero-knowledge proof (ZKP) on the Bitcoin mainnet for the first time in history. This was performed in a series of on-chain transactions on Tuesday, with the final verification occurring at Bitcoin block 853626, Decrypt was told.

The team will also present this feat in front of a live audience at Bitcoin 2024 in Nashville on Thursday to prove that the grandfather blockchain can already do what was long dismissed as impossible.

“The achievement unlocks unlimited scaling and functionality on Bitcoin without requiring additional changes to Bitcoin’s base layer,” said BitcoinOS.

BitcoinOS is a project aiming to construct a trustless “superlayer” of interoperable rollups on Bitcoin. Rollups are layer-2 blockchains that allow for faster, cheaper, and more programmable transactions that are later “rolled up” and settled on a more secure layer-1 chain.

For rollups to work, ZKPs are necessary—a cryptographic method for proving that off-chain information is true without disclosing the information itself. Rollups and ZKPs are already a core technology for scaling the Ethereum network, but have been left out of the Bitcoin scaling conversation due to perceived technical constraints.

That’s forced Bitcoin developers to pursue suboptimal scaling solutions, such as sidechains, which require their users to trust centralized companies and federations not to steal their BTC. Meanwhile, though the more well-known Lightning Network requires no such trust, BitcoinOS said other limitations have left it trending back towards centralization in practice, and lacking in broader adoption.

“The Lightning Network was, unfortunately, a very overhyped scaling solution,” said Edan Yago, core contributor to BitcoinOS, to Decrypt. “As a technology, because it’s pre-funded, and because you need to hop between multiple players, it is only appropriate for a very small number of niche applications.”

When the team released its whitepaper in April, BitcoinOS claimed its rollup system would render sidechains and other layer-2 solutions “completely obsolete” by letting users bridge their BTC back and forth between rollups in a near-trustless manner.

In its live presentation, BitcoinOS said it will show that ZKPs can be used to create covenants—conditional payments that cannot be executed unless the right proof is provided. This is the key to building a decentralized Bitcoin bridge, a “holy grail” scaling solution that most thought would require a soft fork to Bitcoin’s code to make a reality.

As the first system enabling “permissionless” upgrades to Bitcoin, Yago says BitcoinOS solidifies Bitcoin’s role as “permaware, more reliable and permanent than any other chain or software.”

In his view, this makes Bitcoin the best foundation for building decentralized financial services and investment products, the most significant of which—mortgages, airports, power stations, and the like—involve contracts that last for decades. If Bitcoin became an unstable foundation through frequent soft forks, it would become unsuited for this purpose.

“Every single time you have a soft fork, not only are you introducing more risk into the system... but you’re also creating significant frictions within the community of users,” Yago argued. “Just like we saw with the blocksize wars... it causes major unease and uncertainty, which is exactly what you don’t want.”

When discussing Bitcoin’s blocksize wars in May, Ethereum co-founder Vitalik Buterin praised ZKPs as a technological solution that could have diffused political tensions around Bitcoin’s scaling debate by creating better layer-2 scaling solutions that satisfied all sides. He also referenced BitVM, the computing framework from which BitcoinOS took inspiration.

“You want reliability, you want stability, you want boring,” Yago argued. “Soft forks are not boring, and therefore they should be rejected.”

Edited by Ryan Ozawa.