Key Takeaways:
Security firm Project Eleven on Thursday unveiled a cryptographic technique designed to let Bitcoin users prove wallet ownership after quantum computers become capable of forging digital signatures, addressing what the industry calls "Q-Day."
"How do you prove you still own a wallet after a quantum computer can forge its signatures?" Alex Pruden, chief executive officer at Project Eleven, said. "After Q-Day, once a quantum computer can derive an ECC private key from its public key, a valid signature no longer proves ownership."
The technique uses a wallet's key derivation path, allowing users to prove they control the parent key used to generate a wallet's private key without revealing it. Because a quantum computer cannot reconstruct that parent key, the method can distinguish a legitimate owner from an attacker even after a wallet's private key has been compromised, according to Project Eleven. The work was developed with Jim Posen, lead maintainer of the open-source Binius zero-knowledge proof system, and builds on "signature lifting," a concept first proposed by researchers Alon Sattath and Robert Wyborski.
The proposal comes as the industry accelerates preparations for a post-quantum future. In February, Bitcoin developers advanced BIP-360 into formal review, laying groundwork for quantum-resistant upgrades. In March, BTQ Technologies released the first working implementation on its Bitcoin Quantum testnet. Coinbase's quantum advisory council warned in June that roughly 7 million Bitcoin could eventually be vulnerable if owners fail to move funds to quantum-safe addresses. President Donald Trump that same month signed executive orders speeding the federal government's transition to post-quantum cryptography.
"As much as I'd love for the entire world to take a quantum migration plan seriously, the reality is that some digital asset wallets will miss the window," Pruden said. "This gives them a fallback: prove ownership through derivation, not signature, even after that window closes."
The prototype is unaudited and would require blockchain protocol support before it could be used on the Bitcoin network. Project Eleven funded Posen to implement the approach using Binius, an open-source proof system designed to accelerate hash-heavy cryptographic operations. The recovery mechanism is intended for users who miss a future migration to quantum-safe addresses, offering a fallback rather than a replacement for proactive migration.
This article is for informational purposes only and does not constitute investment advice.
