The rise of quantum computing is sparking growing concern among European financial authorities. Regulators, including the EBA, ESMA, and EIOPA, have officially flagged this technological threat in their report on financial system vulnerabilities. While quantum computers capable of breaking current cryptographic systems are not yet operational, the prospect of such a breakthrough is pushing institutions to demand greater vigilance regarding blockchain security, particularly that of Bitcoin.
The main point of contention lies in the exposure of public keys within the distributed ledger. Currently, nearly 6.9 million BTC — representing approximately 34% of the total circulating supply — are stored in output formats where the public key is directly accessible. Whether through legacy P2PK addresses, address reuse, or the recent Taproot standard, these funds could, in theory, become a prime target for an attacker exploiting Shor's algorithm. While these figures highlight a potential vulnerability, it is crucial to note that no machine today possesses the computing power required—estimated at several hundred thousand physical qubits—to compromise the elliptic curves securing the network.
In response to this scenario, the development community is actively working on structural solutions. Notably, BIP-360 proposes the introduction of an output format called P2MR, aimed at limiting the visibility of public keys on the network. In parallel, BIP-361 outlines a more robust migration strategy, planning a gradual transition to hardened protocols. These proposals not only seek to prevent future attacks but also aim to establish a framework that allows users to secure their holdings before quantum technology becomes a concrete threat.
The challenge is not only technical but also temporal. While the NIST timeline, which plans to phase out classic cryptographic standards by 2035, serves as a benchmark for institutions, the migration of Bitcoin requires massive coordination. The goal is to make funds resistant to future computing capabilities while ensuring the network's longevity. Although the deadline may seem distant, the complexity of modifying protocols and migrating millions of transactions necessitates rigorous foresight to prevent any major security flaws during the transition to the post-quantum era.