Security firm Project Eleven has introduced a post-quantum cryptography proof scheme aimed at helping Bitcoin users prove wallet ownership after a potential quantum attack. CEO Alex Pruden highlighted the challenge of proving ownership once quantum computers can derive private keys from public keys, rendering digital signatures ineffective. The proposed solution uses the wallet's key derivation path to allow users to demonstrate possession of the parent key without exposing the private key, distinguishing legitimate holders from attackers. The scheme, developed with Jim Posen of the open-source zero-knowledge proof system Binius, is based on the "signature lifting" technique by researchers Alon Sattath and Robert Wyborski. This approach ensures that even if a wallet's private key is compromised, the parent key remains secure, providing a method to verify ownership post-quantum attack.