Project Eleven has introduced a zero-knowledge proof prototype to secure Bitcoin ownership against potential quantum computing threats.
On July 15, Project Eleven, a company specializing in post-quantum cryptography, introduced a prototype of a zero-knowledge proof designed to help Bitcoin wallet owners verify their ownership in a future where quantum computers could compromise digital signatures.
Project Eleven is working on a new post-quantum primitive to address a significant challenge in cryptocurrency: proving wallet ownership after quantum computers can forge signatures.
— Project Eleven (@projecteleven) July 15, 2026
Zero-knowledge proofs allow users to demonstrate control over their funds without disclosing sensitive information. The proposed mechanism would enable users to prove control over both their current wallet key and an earlier key within the wallet's structure.
Although the mechanism is still in development and not yet functional on the Bitcoin network, it aims to facilitate the transfer of funds to addresses secured against quantum attacks.
Understanding the Mechanism
The term "Q-Day" marks the point when quantum computers can effectively reverse-engineer private keys from public ones, allowing both an attacker and the wallet owner to produce valid signatures.
"Once we reach Q-Day, valid signatures will no longer guarantee ownership," noted Alex Pruden, co-founder and CEO of Project Eleven.
The proposed system employs a hierarchical deterministic wallet structure, where multiple addresses derive from a single root secret. Users must show knowledge of data above their desired address, allowing verification of ownership without revealing the root secret.
Project Eleven claims that while quantum computers could derive a private key from a public key, they would struggle to recover the parent key due to the secure derivation process involved.
The prototype is linked to specific messages, enabling users to confirm their permission for transactions, such as transferring funds to new quantum-resistant addresses.
Details of the Prototype
Developed in collaboration with Jim Posen, a leading proof system developer, the prototype's source code is available on GitHub. The approach is based on a method established by researchers in 2023, which allows for the conversion of signatures vulnerable to quantum attacks into post-quantum proofs.
The implementation, recognized as the first working model of this method, was developed by Olaoluwa Osuntokun, CTO of Lightning Labs. Testing revealed that proof generation on a standard MacBook took about 243 milliseconds, with peak memory usage of 2.1 GB.
Currently, the prototype supports three Bitcoin address types: legacy P2PKH, native SegWit P2WPKH, and nested SegWit P2SH-P2WPKH, while Taproot addresses are not yet incorporated.
This initial version is still in early stages and has not undergone auditing. It does not facilitate the recovery or transfer of existing assets and cannot protect funds already compromised.
Preparing for Quantum Challenges
The initiative aims to assist users unable to transfer their funds during potential post-quantum transitions. It complements other proposals for new address types without replacing them entirely.
A recent Bitcoin Improvement Proposal (BIP-360) aims to create a new Pay-to-Merkle-Root (P2MR) output, expected to enhance Bitcoin's resilience against quantum threats. The proposed structure allows for future integration of post-quantum spending conditions.
In light of the estimated 7 million BTC vulnerable due to outdated address formats, experts are advocating for cryptographic proofs to replace traditional signatures. Project Eleven's proposal exemplifies one of the potential solutions, but the adoption of such mechanisms will ultimately depend on community consensus within the Bitcoin network.
As the industry grapples with the implications of quantum computing, key challenges remain, including ensuring wallet compatibility and reaching agreement on protocol changes.
