<\/p>\n
A Swiss non-profit working on the world\u2019s first zero-knowledge light client for Bitcoin, has reached a major milestone towards bringing zero-knowledge proofs to the most valuable crypto network.<\/p>\n
ZeroSync\u2019s verifier for the Bitcoin network\u2019s block headers makes it possible to build a zk proof-based light client for the network, the first step in a roadmap of permissionless innovation, according project lead Robin Linus.<\/p>\n
In the near term, a light client might let you run a Bitcoin full node on, say, a mobile phone. But that roadmap includes a second-layer protocol on top of Bitcoin, that can bring tokens \u2014 such as stablecoins \u2014 to the Bitcoin network, along with a 20 to 50 times throughput increase, without requiring any sort of fork.<\/p>\n
\u201cWhat is cool about that solution is that, first of all, you can process about 100 transactions on the base layer,\u201d Linus told Blockworks. \u201cAnd in addition to that, we also get perfect privacy \u2014 you can encrypt both the transaction amounts and the transaction graphs, and then you basically get best-in-class privacy, comparable to Zcash.\u201d<\/p>\n
The privacy benefit is essentially a byproduct of the protocol\u2019s use of STARKs, the proving system invented by StarkWare<\/a>, not a deliberate design choice.<\/p>\n ZeroSync received a grant from Geometry Research in 2022, one from StarkWare earlier this year, and has since formed the foundation. The group\u2019s work is the first effort to use StarkWare\u2019s Cairo programming language outside of the Ethereum ecosystem.<\/p>\n A soft fork would be required to enable trustless bitcoin bridging on the layer-2 network that ZeroSync envisions. Yet even without that, the network can permissionlessly support useful features, such as token transfers where the fees are paid in a stablecoins, removing the need for bitcoin (BTC<\/a>) to pay for transactions.<\/p>\n Bitcoin is resistant to change by design, requiring consensus from Core developers, and near-consensus from full node operators, including miners. The prior soft fork in 2021, called Taproot<\/a>, was years in the making and only activated after more than 90% of node operators signaled their assent.<\/p>\n \u201cWe want it to be hard to change so that it can be hard money, but some changes are necessary,\u201d Linus said. \u201cIt seems to be that there is a consensus that at some point we do want to have some kind of [zk proof] verifier on Bitcoin.\u201d<\/p>\n Linus sees ZeroSync\u2019s role as helping figure out what kind of approach makes the most sense.<\/p>\n \u201cWe try to participate in the community and push that forward,\u201d he noted. \u201cEverything has to be free and open-source, otherwise it will never get into the main layer.\u201d<\/p>\n Meanwhile, the chain state proof they\u2019ve completed won\u2019t require any kind of fork.<\/p>\n Zk proof technology is still in its infancy<\/a>. There are many different proof systems available with various different tradeoffs to consider. Those choices have ramifications for virtual machines built on top. Linus recognizes it would be quite hard to reach consensus on just one.<\/p>\n Eric Wall, a board member of the StarkNet Foundation, and a bitcoin thought-leader, articulated<\/a> one of the challenges with Bitcoin\u2019s decision-making process in this area.<\/p>\n \u201cHow is the Bitcoin community ever supposed to reach consensus on enshrining a specific zk-verifying opcode, when the zk community itself is not in any way in consensus on what type of zkVM would be ideal for Bitcoin for the next year, let alone the next 5 or next 100 years?\u201d<\/p>\n Fortunately, Linus sees a likely solution coming via the Simplicity programming language<\/a>, first unveiled by Blockstream<\/a> about five years ago.<\/p>\n Simplicity, a smart contract<\/a> language similar to Solidity on Ethereum, has been described<\/a> as \u201cBitcoin\u2019s last soft fork.\u201d If it is activated, it will \u201cvastly increase the scripting capabilities of Bitcoin,\u201d Linus said.<\/p>\n \u201cWe are already starting to experiment with it because Blockstream just activated it on the Liquid<\/a> testnet\u2026that will be the first step for us to experiment with a [zk proof] verifier on Bitcoin\u2019s main layer.\u201d<\/p>\nWaiting for Bitcoin Simplicity<\/h2>\n