Crypto’s first quantum attack will look like unexplained breach: Quantus founder
The first sign that quantum computing has broken modern cryptography probably won't be a splashy theft of Satoshi Nakamoto's dormant Bitcoin. It could just be a wave of unrelated crypto wallet breaches with no trace of how an attacker did it, according to the founder of b…
Intelligence analysis by Llama

The arrival of 'Q-day' — a hypothetical future moment when quantum computers become powerful enough to break standard public-key cryptography — is unusually difficult to detect. A sufficiently powerful quantum computer could derive a private key from public keys exposed onchain, allowing an attacker to move funds without compromising a wallet, device or exchange's internal systems.
Imagine someone has a super-powerful computer that can break secret codes. They might not try to steal a lot of money at once, but instead, they might quietly break into many different wallets and take a little bit of money from each one. This would be very hard to detect because there would be no clear sign of how they broke in.
Analysis
Q-day Timeline Hard to Pin Down
In March, Google accelerated its post-quantum migration timeline to 2029 as an AI-assisted breakthrough showed elliptic curve cryptography can be cracked with far fewer physical qubits than previously forecasted. NGRAVE CEO Roy Blackstone said earlier quantum forecasts failed to account for the parallel development of AI.
First Target May Not Be Satoshi's Bitcoin
Much of the fear around Q-day in crypto is what will happen if a quantum computer cracks the keys securing Satoshi Nakamoto's estimated Bitcoin holdings, worth $63 billion at the time of writing, which could be suddenly dumped on the market. However, Smith said the first targets may be military systems and state secrets, while crypto attackers could go for even more valuable keys.
Q-day Uncertainty
Despite growing urgency, there is little agreement on when a quantum computer capable of breaking modern cryptography will be ready. Smith, whose company is developing a blockchain network aiming to be quantum-resistant from launch, said there was a '50-50' chance it could happen by 2028, arguing that continued AI-assisted improvements in quantum algorithms and hardware research are making forecasts less reliable. Cheetham said the early 2030s 'definitely is almost a certainty' and that an earlier arrival was 'more of a trailing probability.'
Key points
- The first sign of a quantum attack may not be a splashy theft of Satoshi Nakamoto's Bitcoin, but rather a wave of unrelated crypto wallet breaches.
- A sufficiently powerful quantum computer could derive a private key from public keys exposed onchain, allowing an attacker to move funds without compromising a wallet, device or exchange's internal systems.
- The uncertainty of when a quantum computer capable of breaking modern cryptography will be ready makes it crucial for blockchains to migrate to post-quantum signatures.
If blockchains migrate to post-quantum signatures in time, the damage from a quantum computer breaking modern cryptography could be minimized. This would allow the crypto industry to continue growing and developing without major disruptions.
If a quantum computer breaks modern cryptography and blockchains are not prepared, the consequences could be catastrophic. This could lead to a loss of trust in the crypto industry and potentially even the collapse of some blockchains.


