Bitcoin’s current scalability challenge rooted in its design principles is a pressing concern as its popularity soars. Bitcoin’s decentralized nature and consensus mechanism, while providing robust security, come at the cost of limited transaction throughput.
Segregated Witness (SegWit) and Taproot represent significant upgrades to the Bitcoin network, enhancing its capabilities and security. However, the scalability issue still persists.
Introducing opZKP
The rapid evolution of ZKP has offered a new option for us. We proposed opZKP opcode upgrade in April 2023 as a soft fork to the Bitcoin community, making continuous improvements to address these challenges while maintaining the core principles of Bitcoin.
opZKP, leveraging ZKP technology, enables Bitcoin to verify arbitrary computations before authorizing any UTXO spending. This is achieved by generating zero-knowledge proofs of such computations off-chain and subsequently verifying these proofs on-chain, facilitated by introducing new opcodes to the Bitcoin scripting language.
zkBTC: Bridging Bitcoin and Ethereum Ecosystem
We have been developing flagship applications based on the proposal since then.
zkBTC is a native bridge between the Bitcoin and Ethereum ecosystem, rooted in ZKP technology. It enables Bitcoin holders to safely engage with Ethereum’s flourishing crypto ecosystem while fostering the gradual development of a native ecosystem within Bitcoin.
The $zkBTC token, issued by the zkBTC project, is designed as an ERC-20 token, pegged to $BTC at 1:1. Users can simply mint $zkBTC by depositing $BTC to a designated Bitcoin address, then generating a proof off-chain and validating it within an Ethereum smart contract. This process ensures that the smart contract verifies the deposit transaction on the Bitcoin network before minting the corresponding $zkBTC tokens for the user, upholding the 1:1 pegging.
For redemption, users call the Ethereum smart contract to destroy some of their $zkBTC tokens. A proof is then generated off-chain. Depending on the activation of the proposed opZKP opcode, this proof is verified either by the Bitcoin network directly or in a tamper-proof container as an interim solution, followed by UTXO expenditure.
What’s Our Interim Solution?
The interim solution mentioned above is our multi-signature validator within the zkBTC project, designed to deliver a secure, efficient, and trustless solution that meets the needs of our users. It is a critical factor in ensuring that users can trust the system without concerns about the safety of their assets.
There are two key ingredients in our interim solution
All the private keys are safe-kept in a secure container protected by MPC or TEE, ensuring nobody including us and the container operator could have access.
The container also ensures integrity, meaning the private keys will be called to sign a UTXO expenditure only after the zk-proof has been verified.
Connect with Us
We recognize that achieving scalability without compromising the network’s core principles is an ongoing endeavor, and we’re fully prepared for this journey. Stay tuned for more updates.
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