A week-long coding challenge has achieved a dramatic breakthrough in quantum-safe Bitcoin technology, with AI-assisted developers cutting the estimated cost of preparing quantum-safe transactions by 79%. The cost reduction brings the price down from $320 to approximately $66, representing a significant advancement in making quantum-resistant Bitcoin more accessible. StarkWare's experimental method, which uses hash-based cryptography to move eligible Bitcoin under existing consensus rules without requiring protocol changes, was first demonstrated on August 26 through MARA's Slipstream service, requiring roughly 3,100 GPU-hours and the original $320 compute cost. The breakthrough came through StarkWare's Quantum-Safe Bitcoin Optimization Challenge launched on September 16, with Yukon Research and Eigen Labs offering over $20,000 in prizes.
The coding challenge delivered substantial performance improvements through AI-assisted optimization. Sixty-two accepted submissions, many built with AI coding tools, pushed processing speed roughly six times faster on identical hardware. Benchmark tests on an RTX 4090 GPU showed the most dramatic results, with pinning speed jumping from about 146 million verified candidates per second to more than 880 million. However, this benchmark figure has not yet been demonstrated in a second-mined transaction, and the cost estimate of $66 covers only GPU compute, excluding network fees. The method addresses a specific risk where a sufficiently powerful quantum computer could derive private keys from exposed public keys, though no such machine exists today.
European financial authorities have issued a stark warning that advanced quantum computers could undermine blockchain cryptography before the technology achieves commercial viability. The Joint Committee of the European Supervisory Authorities (ESAs), comprising the European Banking Authority (EBA), European Securities and Markets Authority (ESMA), and European Insurance and Occupational Pensions Authority (EIOPA), issued their Autumn 2026 Risk and Vulnerabilities report warning that threats could materialize earlier than any commercially viable quantum application. According to the report, an advanced quantum computer could undermine cryptography systems widely used to secure communications, transactions, databases and blockchains. The European Commission's 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. ESMA's technical analysis published in May examined the mechanics in detail, noting that sufficiently advanced quantum computers could use Shor's algorithm against public-key schemes including RSA and elliptic-curve cryptography, while practical quantum attacks remain beyond current noisy intermediate-scale quantum, or NISQ, machines.
The EU warning reveals that approximately 6.9 million Bitcoin, worth roughly $586 billion, are currently vulnerable to quantum attacks due to legacy address structures. As reported by CryptoQuant founder Ki Young Ju, his February estimate of 6.89 million BTC included roughly 1.91 million BTC associated with directly visible public keys and other coins whose keys may have been revealed through previous spending behavior. The Satoshi-era bitcoin held in older, legacy addresses or reused addresses could face greater risk, as their public keys are already onchain and visible to potential attackers. Glassnode's May research produced a different calculation, measuring 6.04 million BTC (30.2% of issued supply) as having public-key exposure at rest, with 1.92 million BTC classified as structurally exposed due to output types that reveal keys by design. This contrasts with many unspent bitcoin outputs that still hide the public key behind a cryptographic hash, leaving them less exposed for now.
The breakthrough in quantum-safe Bitcoin technology comes as the industry prepares for potential migration, with Bitcoin's developer community responding separately. Bitcoin's developer community has proposed BIP-360, a quantum-resistant address proposal that reached testnet with over 50 participating miners in March 2026, and BIP-361 addressing migration policy that would eventually prevent new funds from being sent to quantum-vulnerable output types. However, moving to quantum-resistant signatures would require network-wide consensus, and holders of exposed coins would need to move them before such an attack becomes possible. Institutional custodians have begun preparing without waiting for Bitcoin to choose a final signature system - as reported by crypto.news, Coinbase is designing post-quantum Bitcoin custody capable of supporting multiple potential signature schemes, while Ledger CTO Charles Guillemet argues that migration may take years due to the complexity of changing wallets and custody systems. Neither BIP is an activated Bitcoin consensus rule, leaving the technical standard and migration policy unsettled.
