Overview
- The Joint Committee of European financial supervisors issued an Autumn 2026 assessment that warned an advanced quantum computer could break the cryptography protecting blockchains and other financial systems, a report published on Sept. 23 that pushed preparation into the near term.
- The authorities made clear no existing quantum machine can today crack Bitcoin or Ethereum keys but flagged 'harvest now, decrypt later' as a major worry because attackers can store public ledger data or encrypted records for future decryption.
- New research from Google Quantum AI and collaborators has sharply lowered prior estimates of the quantum resources needed to attack elliptic-curve cryptography, increasing pressure on networks and custodians to act sooner.
- Protocol responses are still in design: the Ethereum Foundation has an internal target to reach quantum resistance by December 2029, while Bitcoin developers are debating draft proposals (BIP-360 and BIP-361) to introduce post-quantum outputs and migration rules.
- The European Commission’s roadmap requires member states to begin post-quantum migration by the end of 2026 and protect high-risk systems by 2030, and analysts’ estimates of exposed Bitcoin holdings vary roughly between 6.0 million and 7.0 million BTC, prompting custodians to build crypto-agile custody options now.