Europol’s 2026 security assessment confirms that Bitcoin wallets using legacy Pay-to-Public-Key (P2PK) and reused Pay-to-Public-Key-Hash (P2PKH) addresses are critically at risk from quantum-enabled attacks. The primary issue is that these older formats have their public keys permanently visible on the public ledger. Unlike modern addresses that keep the public key hidden behind a hash until a transaction is initiated, these exposed keys can be targeted by quantum computers using Shor’s algorithm to derive the corresponding private keys, leaving these specific funds with no retroactive cryptographic fix.
The warning highlights a significant portion of early Bitcoin supply, including the legendary 'Satoshi-era' coins, which remain locked in these vulnerable formats. While the Bitcoin protocol can be upgraded with post-quantum cryptographic signatures (PQS) via a soft fork, such a fix only protects addresses where the public key has not yet been revealed. For the millions of BTC stored in P2PK addresses, the cryptographic vulnerability is already public, making them the primary targets for 'harvest now, decrypt later' strategies by state actors or advanced cybercriminal syndicates.
In the U.S., this intelligence report is expected to accelerate regulatory pressure on crypto exchanges and custodians to enforce 'quantum-ready' migration standards. The Department of Justice and Europol are reportedly concerned that the eventual cracking of these legacy wallets could lead to a massive, uncontrollable wealth transfer if users do not move their funds to quantum-resistant formats. For long-term holders, this means an immediate audit of cold storage solutions is necessary to ensure assets are not residing in outdated 2009-2012 era address types.
Market sentiment remains sensitive to these developments, as the potential 'unlocking' of long-dormant legacy coins could introduce significant sell pressure and volatility. Throughout the rest of 2026, the crypto community should watch for new Bitcoin Improvement Proposals (BIPs) specifically designed to incentivize the migration of legacy funds. The technical debate will likely shift from scaling to survival, as the industry races to outpace the development of practical quantum computers.