Is quantum Bitcoin hacking here?

Bitcoin was built on the principle that once funds are secured by a private key, only the holder can access them. But what if that assumption no longer holds?

In what was reportedly a now-deleted post on X, former Wall Street trader Josh Mandell alleged that quantum computers are being used to siphon Bitcoin (BTC) from long-dormant wallets — especially those of owners presumed inactive or deceased.

According to him, a “large player” has found a way to extract BTC directly from these wallets without going through the open market, leaving blockchain analysts as the only means of detection.

If true, the implications would be profound: Such activity would undermine the very foundation of Bitcoin’s security and ownership model. But what does the onchain evidence actually show? And can it be demonstrated that the technology needed to achieve this even exists today?

This article unpacks Mandell’s claims, expert reactions, the current state of quantum computing and more.

Did you know? Over 2.3 million-3.7 million BTC are estimated to be lost forever due to forgotten private keys or inactive wallets.

What Josh Mandell claimed

Mandell alleges that old, inactive Bitcoin wallets are being quietly drained using quantum computing. He contends that a major actor is accumulating BTC not via exchanges, but by accessing the private keys of wallets whose owners are unlikely to be aware or respond.

Key points of his claim:

• Targeted wallets: Long-dormant accounts, often assumed abandoned or tied to deceased owners.
• Off-market accumulation: Coins are extracted without creating price disruptions or large sell orders.
• Detection risk: Only blockchain forensics could reveal suspicious movement patterns, yet Mandell admits no clear proof exists.
• Quantum leap: He implies that quantum technology has reached a point where it can crack Bitcoin’s cryptographic defenses in ways classical computing cannot.

Crucially, Mandell offers no hard evidence. His position is that the scenario is technically possible — and may already be unfolding — but this remains unverified.

Did you know? Scientists at Oxford have achieved an error rate of just 0.000015% (one error in 6.7 million operations) for certain quantum operations — a new world-record fidelity.

Technical feasibility: Can quantum tech do this now?

Mandell’s claim hinges on quantum computers being advanced enough to break the public-key cryptography that secures Bitcoin wallets. Assessing this requires examining what such an attack involves and how close current technology is to making it possible.

Bitcoin relies on the Elliptic Curve Digital Signature Algorithm (ECDSA), specifically the secp256k1 curve.

When coins are spent, a wallet’s public key becomes visible onchain. If an attacker could derive the private key from that public key, they could seize any remaining funds.

Shor’s algorithm, a quantum algorithm, could, in theory, perform this exponentially faster than classical methods — but only with quantum hardware far beyond today’s capabilities.

In practice, however, several technical hurdles remain:

• Logical qubits and error correction: Physical qubits are unstable. To build fault-tolerant logical qubits, error correction multiplies the hardware requirements.
• Scale of qubits needed: Estimates suggest hundreds of thousands (possibly millions) of physical qubits would be required to break a single secp256k1 key once error-correction overhead is included.
• Gate fidelity and error rates: Operations must be nearly flawless. Current chips, like Google’s 105-qubit Willow, are just reaching thresholds where error correction begins to help, but they remain far from full fault-tolerance.
• Expert projections: Most researchers put a realistic ECDSA-breaking quantum computer at least a decade away and longer without breakthroughs in coherence times, scaling and error suppression.

Mandell implies this stage has already been reached — that someone has hardware powerful and discreet enough to crack private keys from dormant wallets without detection.

But, based on public knowledge, today’s devices are nowhere near the required scale or stability.

Did you know? One Bitcoin wallet tied to the Mt. Gox hack still sits dormant and holds 79,957 BTC, making up about 0.4% of Bitcoin’s total supply.

Pushback from the Bitcoin and crypto communities

The response from the Bitcoin community has been swift and skeptical.

Harry Beckwith, founder of Hot Pixel Group, stated, “There is literally no chance this is currently happening.” Matthew Pines of the Bitcoin Policy Institute called the theory “false” and criticized its lack of evidence.

Their arguments follow several lines:

• Quantum capability isn’t there yet: While progress is steady, current machines lack the qubit counts, error correction and processing power needed for cryptographic attacks on Bitcoin. Quantum risk is real but remains a future concern.
• No supporting evidence: Onchain movements of dormant coins have been observed, but none clearly indicate quantum-driven theft. Most are better explained by owners reactivating wallets, inheritance transfers or security upgrades.
• Limits of exposed public keys: An attack would only be possible where public keys are revealed, and even then, an adversary would need to calculate private keys in real time. Many long-inactive wallets never exposed their public keys at all.
• Blockchain transparency: Dormant wallets are closely tracked by analytics firms. Large-scale stealth drains would almost certainly trigger red flags, which haven’t been seen.

The prevailing view is that while quantum computing will eventually pose a threat, Mandell’s suggestion that it is already being weaponized against Bitcoin is premature.

What onchain data shows (or doesn’t show)

If quantum-based thefts were happening, the blockchain should show distinct signs. So far, it doesn’t.

• Dormant wallets reactivated: Several old wallets from the Satoshi era (2009-2011) have moved large sums. For instance, 80,000 BTC across eight addresses that had been inactive for 14 years was moved. But analysts believe these were voluntary migrations to modern address formats like SegWit, not unexplained drains.
• No anomalous signatures: There is no published evidence of transaction patterns that suggest quantum key breaks, such as simultaneous extractions timed to public key exposure. Observed activity aligns with routine actions like consolidations or fee optimization.
• No confirmed thefts: Aside from reactivations, no cases of loss tied directly to quantum computing have been verified. Old addresses tend to move coins quietly, without evidence of forced transfers.
• Legacy vulnerabilities remain: A meaningful amount of BTC still sits in older formats such as pay to public key (P2PK) and P2PK hash (P2PKH), which expose public keys and are theoretically weaker. This highlights a potential risk if quantum capabilities advance, but there is no evidence of exploitation yet.

In short, onchain data confirms vulnerabilities exist but offers no proof they’re being exploited with quantum methods.

Mandell’s claim in perspective

Mandell’s warning that quantum computers are already stealing Bitcoin from dormant wallets remains unproven.

The ECDSA cryptography securing Bitcoin is still considered safe, with most experts estimating at least a decade before quantum hardware could realistically break it.

Some forecasts suggest risks could emerge in the late 2020s, particularly for wallets with exposed public keys. For now, blockchain evidence points to benign explanations such as reactivation, migration and consolidation.

The signs to watch are clear: sudden large transfers from legacy formats, rapid moves immediately after public key exposure or verifiable demonstrations of private key extraction. Until those appear, the quantum threat should be viewed as a future challenge to prepare for, not a present reality.