European Supervisory Authorities warn that quantum computing poses an escalating threat, potentially undermining Bitcoin and blockchain encryption sooner than commercial widespread use. The alert, from the continent’s top financial watchdogs, adds official weight to a long-simmering debate within the cryptocurrency industry about preparing for a post-quantum world.
In its Autumn 2026 risk assessment report, published Wednesday, September 23, the Joint Committee of the European Supervisory Authorities (ESAs) stated that an advanced quantum computer could break the cryptographic systems used to secure digital transactions, communications, and databases. The committee includes the European Banking Authority (EBA), the European Securities and Markets Authority (ESMA), and the European Insurance and Occupational Pensions Authority (EIOPA).
Understanding the Supervisory Authorities’ quantum threat assessment
The theoretical danger, which regulators now see approaching reality, lies in a quantum computer’s ability to run algorithms like Shor’s algorithm. Such a machine could effectively reverse the cryptographic process that protects Bitcoin wallets, deriving a user’s private key from their public key. This would grant an attacker complete control over the associated funds.
While no such computer exists today, the report emphasizes that “threats could materialize earlier than any viable commercial application.” This highlights the risk of a breakthrough being achieved by a state-level actor or a well-funded private entity long before quantum computers are available on the open market.
The concern is particularly acute for older Bitcoin addresses, where public keys are already exposed on the blockchain. This includes older pay-to-public-key (P2PK) outputs and any reused addresses, which present a particular risk since their public keys are already visible on the blockchain.
Modern Bitcoin transactions often use address formats that hash the public key, only revealing it when the funds are first spent. This provides a layer of protection, but it does not safeguard the vast number of unspent outputs (UTXOs) from Bitcoin’s early days.
The latest regulatory pronouncements from Europe underscore a growing focus on the security of digital assets across various platforms, such as understanding Celestia’s blob economy proposal.
Gauging the approaching timeline
For years, the quantum threat was considered a distant, almost science-fiction possibility. But recent advancements have drastically shortened the projected timeline.
The ESAs’ report points to the danger of “harvest now, decrypt later” attacks, where malicious actors are already collecting today’s encrypted data with the intent of breaking it once a capable quantum computer is built. This means that even data secured today is already vulnerable to a future adversary.
A March 2026 study by Google Quantum AI and its partners provided a sobering update, calculating that breaking Bitcoin’s 256-bit elliptic-curve cryptography might require as few as 1,200 logical qubits. This represented a startling 20-fold reduction from previous estimates.
While building a stable, fault-tolerant quantum computer with that capacity remains a monumental engineering challenge, the revised figures place the goal within the realm of near-term possibility rather than distant theory. This accelerated timeline adds pressure on all digital financial systems, including those that monitor Kalshi’s ether futures volume.
Further fueling the sense of urgency, the rapid pace of development in quantum computing demonstrates how quickly this field is advancing. The convergence of official warnings and revised academic research paints a clear picture: the window to prepare for the quantum era is closing.
The difficult path to quantum resistance
Securing Bitcoin against a quantum attack is not a simple software patch. It requires a fundamental and coordinated upgrade across a decentralized, global network. Unlike a traditional financial institution, Bitcoin has no central authority that can mandate a security update. Any transition to quantum-resistant cryptography would necessitate network-wide consensus among developers, miners, and users—a notoriously complex and political process.
Discussions are already underway. In February 2026, Bitcoin developer Jameson Lopp and several co-developers put forward a draft proposal to phase out vulnerable signature schemes. The plan suggested a multi-year transition, culminating in restrictions on moving funds from unmigrated legacy addresses five years after activation.
However, this remains a draft and is far from being adopted, highlighting the significant governance challenges inherent in updating a decentralized network like Bitcoin.
Other protocols are moving more decisively. The Ethereum Foundation has a dedicated post-quantum research team and has set a target of December 2029 for achieving full quantum resistance across its entire protocol stack. This proactive roadmap stands in contrast to Bitcoin’s more cautious, consensus-driven pace. The broader tech world is also preparing, with the U.S.
National Institute of Standards and Technology (NIST) having finalized its first post-quantum cryptography standards back in August 2024. These standards provide a blueprint for building next-generation secure systems, putting pressure on all networks to adopt them.
Europe signals a proactive regulatory stance
The warning from the ESAs is more than just an observation; it’s a signal of intent. European regulators are positioning themselves to enforce higher standards of cryptographic security. The report notes that existing frameworks, such as the EU’s Digital Operational Resilience Act (DORA), already obligate financial institutions to use state-of-the-art cryptography to guard against emerging threats. The quantum threat is now officially on that list.
This formal warning aligns with a broader strategy from Brussels. The European Commission’s (EC) post-quantum roadmap calls on member states to begin transitioning by the end of 2026, with high-risk use cases to be protected by 2030. By including blockchains in their latest risk assessment, the ESAs are making it clear that digital asset networks will be expected to meet these future standards.
This puts the onus on developers and network participants to accelerate their transition plans. For Bitcoin, the pressure is mounting. The protocol’s legendary security has been its primary selling point for over a decade. As European regulators formalize the quantum threat, the race is on to ensure that Bitcoin’s digital gold narrative doesn’t get shattered by the immense power of a new computing paradigm.