The looming risk posed by quantum computing technology continues to cast uncertainty on the security of digital assets, with industry voices warning that future attacks may occur without clear evidence or identifiable culprits. Christopher Smith, CEO and co-founder of Quantus Network, said a sudden wave of inexplicable wallet thefts could serve as the first sign that major blockchains have been compromised by quantum computers. He stated that fund movements from previously secured wallets could reveal the breach only after assets have already been stolen.
ETH
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AAPLQuantum threat extends across entire crypto market
Unlike traditional security vulnerabilities, quantum risk is expected to be a systemic issue affecting the entire digital asset sector. Quantus Network estimates that 99.96% of crypto assets, representing about $2.3 trillion, are exposed to a powerful quantum computer able to defeat current cryptography.
In its State of Quantum Report published in May 2026, Quantus concluded that the need for market-wide quantum migration will likely become critical before the end of the decade or in the early 2030s. The timeline for preparations is narrowing as quantum computing capabilities accelerate.
The website migration.fail points to leading networks including Bitcoin, Ethereum, and Solana as still relying on cryptographic signatures vulnerable to quantum attacks. A July Reuters report found that none of the 20 largest blockchains have yet adopted a post-quantum signature algorithm.
Mini dictionary: Quantus Network, a blockchain security company specializing in quantum-resilient solutions for cryptocurrencies and digital assets.
Quantum breaches may leave no physical trace
A quantum-powered attack could bypass the need to breach exchanges or compromise individual devices. According to Smith, a sufficiently advanced quantum computer can derive private keys from public keys visible on-chain and transfer funds directly. This type of attack would not involve a conventional hack or identifiable incursion.
Smith emphasized that when a private key is cracked through quantum means, there is no announcement or clear indicator, and in secure systems, the only evidence may be the absence of a breach trace.
Sean Cheetham, security researcher at Blockchain Capital, expects that rather than targeting the dormant Bitcoin belonging to Satoshi Nakamoto, early quantum attackers might try accessing exchange hot wallets, as unexpected activity there could go undetected for longer periods.
Research from Google supports the quantum risk scenario but does not suggest an immediate threat. In March, Google reported that breaking the widely used 256-bit elliptic-curve cryptography could be possible with under 500,000 physical qubits, which is significantly less than previous estimates. Based on these advances, Google advised that blockchains accelerate the adoption of post-quantum cryptographic protections.
Stablecoins and the risk to Tether’s keys
Speculation about the arrival of “Q-day” — when quantum computers can overcome today’s cryptography — has often centered on the estimated $63 billion in dormant Bitcoin attributed to Satoshi Nakamoto. Smith believes, however, that a greater systemic risk lies in the security of minting and issuance keys used by Tether, the leading stablecoin operator.
If an attacker were to gain control of these keys, it could allow unauthorized issuance of USDt, potentially triggering a severe stablecoin and liquidity crisis. Tether has repeatedly stated that securing its minting keys is a top priority, due to their central role in USDt creation.
The stablecoin sector has expanded rapidly, with recent data from DeFiLlama showing the total stablecoin market at about $300.7 billion. Tether’s USDt represents more than $183 billion, accounting for 60.9% of the sector. The Bank for International Settlements observed that dollar-backed stablecoins held over $270 billion in assets by December 2025 and purchased about $33 billion in U.S. Treasury bills last year.
| Stablecoin | Market Share | Total Market Value |
|---|---|---|
| USDt (Tether) | 60.9% | $183.1 billion |
| Total Stablecoin Market | 100% | $300.7 billion |
The growing ties between the stablecoin sector and traditional finance raise concerns that any major disruption could ripple across both markets, intensifying existing volatility.
Race to post-quantum security intensifies
No currently available quantum computer is capable of breaking current crypto protections, but forecasts for their arrival are narrowing. The “Quantum Horizon” report from June estimates a one-in-six chance that such a device could emerge by 2035, rising to 30% by 2040 and 60% by 2050. Authors caution that these numbers are estimates rather than certainties.
Despite these timeframes, migration to post-quantum cryptography is increasingly urgent. Google announced plans to complete its transition to post-quantum standards by 2029, citing significant progress in quantum hardware and error correction.
Migrating blockchains to quantum-resistant signatures remains a daunting task due to the public, decentralized, and immutable nature of these systems. Quantum-resistant signatures such as Dilithium-5 are much larger in size than classical ECDSA, potentially increasing storage needs and transaction fees.
| Signature Algorithm | Signature Size |
|---|---|
| ECDSA | 64 bytes |
| Dilithium-5 | 4,595 bytes |
For investors, the most significant risk may not be the sudden, obvious collapse of a major blockchain, but rather the subtle signs of compromise revealed when trusted wallets or operators demonstrate unexplained losses.
