After Quantum Computers Can Forge Bitcoin Signatures, This Method Could Still Prove Your Coins Are Yours Security firm Project Eleven has unveiled a cryptographic method that would let Bitcoin holders prove they own a wallet even after a quantum computer cracks its private key, as the industry races to prepare for so-called Q-Day. What happens to your Bitcoin the day a quantum computer can copy your digital signature? That question sits at the heart of a new cryptographic method introduced on Thursday by the security firm Project Eleven, which says it has found a way for people to prove they own a wallet even after quantum machines grow powerful enough to derive private keys and manufacture valid signatures on their own. The company's argument, laid out by chief executive Alex Pruden in a thread on X on Wednesday, flips the usual framing of the quantum debate. According to Pruden, the hardest part of the problem is not shielding a wallet from a quantum attack in the first place. The real puzzle is figuring out who the rightful owner is once such attacks are actually feasible. "How do you prove you still own a wallet after a quantum computer can forge its signatures?" Pruden wrote. "After Q-Day, once a quantum computer can derive an ECC private key from its public key, a valid signature no longer proves ownership. Both the quantum adversary and the legitimate owner are able to produce identical signatures." What 'Q-Day' actually means "Q-Day" is the industry's shorthand for the moment a quantum computer becomes capable of breaking the elliptic curve cryptography that secures Bitcoin transactions. The fear across the sector is straightforward: an attacker with a sufficiently advanced quantum machine could work backwards from a public key to recover the matching private key. Once that becomes possible, a digital signature stops being trustworthy evidence that someone controls a wallet, because the attacker can generate the exact same signature the owner would. In everyday terms, that opens the door to theft. An attacker could single out wallets that are exposed, forge their signatures and move the Bitcoin inside them without ever needing the owner's consent. Proving ownership without revealing the key Project Eleven's answer leans on a wallet's key derivation path. The technique lets a user demonstrate that they control the parent key from which a wallet's private key was generated, all without ever exposing that parent key. Because a quantum computer cannot rebuild that parent key, the firm says the method can still tell a genuine owner apart from an impostor, even in a scenario where the wallet's private key has already been cracked. "So even after Q-Day, an attacker who's broken your address's private key does not hold, and can't compute, the seed phrase it was derived from. Proving you know that parent key, without revealing it, is something only the real owner can do," Pruden wrote. Who built it Pruden said the work was carried out with Jim Posen, the lead maintainer of the open-source Binius zero-knowledge proof system. It builds on an earlier idea called "signature lifting," first put forward by researchers Alon Sattath and Robert Wyborski. Project Eleven funded Posen to implement the approach with Binius, an open-source proof system engineered to speed up cryptographic operations that lean heavily on hashing. The recovery mechanism is aimed squarely at users who fail to make a future move to quantum-safe addresses in time. It arrives as the wider push to ready Bitcoin for a post-quantum world picks up pace. The race to quantum-proof Bitcoin The groundwork has been building all year. In February, Bitcoin developers pushed BIP-360, a Bitcoin improvement proposal, into the formal review process, setting the stage for future quantum-resistant upgrades. In March, BTQ Technologies rolled out the first working implementation on its Bitcoin Quantum testnet, giving developers a place to test the proposal and, at the same time, exposing how hard it is to build consensus for a change that touches the entire network. The warnings grew louder in June, when Coinbase's quantum advisory council pressed blockchain developers to start planning post-quantum migrations now. It cautioned that roughly 7 million Bitcoin could eventually be exposed to quantum attacks if their owners never shift the funds to quantum-safe addresses. Later that same month, President Donald Trump signed executive orders to speed up the federal government's own switch to post-quantum cryptography, adding fresh momentum to the broader effort to get ready for Q-Day. A safety net for the stragglers For Pruden, the proposal is less about the diligent and more about those who slip through the cracks. "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 wrote. "This gives them a fallback: prove ownership through derivation, not signature, even after that window closes." What this means for you • For Bitcoin holders: If quantum computers ever crack Bitcoin's cryptography, this method could let you reclaim a wallet even after its private key is broken, but only if you still control the original seed phrase, so guarding your seed matters more than ever. • For the wider market: Nothing changes today, this is a proposed safeguard and not a live upgrade, and up to 7 million Bitcoin could stay exposed unless owners eventually move funds to quantum-safe addresses. Questions & Answers 1. What has Project Eleven introduced? A cryptographic technique that would let users prove they own a Bitcoin wallet even after a quantum attack. 2. What is Q-Day? It is the moment a quantum computer becomes able to break the elliptic curve cryptography that secures Bitcoin transactions. 3. How does the technique work? It uses a wallet's key derivation path to let a user prove they control the parent key without revealing it, and a quantum computer cannot reconstruct that parent key. 4. Who built it? Project Eleven developed it with Jim Posen, building on "signature lifting," an idea first proposed by researchers Alon Sattath and Robert Wyborski. 5. How many Bitcoin are at risk? Coinbase's quantum advisory council warned that roughly 7 million Bitcoin could eventually be vulnerable to quantum attacks. 6. Who is this method meant for? It targets users who miss a future migration to quantum-safe addresses, offering them a fallback way to prove ownership. https://trendkia.com/en/crypto/kvantama-knpyutara-bitcoin-ki-chabi-tora-den-taba-bhi-malikana-haka-sabita-karane-ka-naya-tarika-aya-samane-8223 TrendKia — Har trend, sabse pehle.