A new Bitcoin Improvement Proposal (BIP) aims to tackle the threat posed by quantum computers by phasing out Bitcoin's legacy signature schemes, which can be vulnerable to quantum attacks, in favor of quantum-resistant alternatives . The proposal, titled “Post Quantum Migration and Legacy Signature Sunset,” was drafted earlier this week by a group of cryptography and blockchain experts, including American software engineer Jameson Lopp and BitcoinQS founder Christian Papathanasiou .
While quantum computers powerful enough to crack Bitcoin's cryptography are not yet here, recent developments have narrowed the window . Some academic forecasts suggest quantum machines capable of threatening Bitcoin could arrive as early as 2027 to 2030, per McKinsey . Bitcoin currently relies on ECDSA and Schnorr signatures to secure transactions . Still, about a quarter of all Bitcoin's unspent outputs have already revealed public keys onchain, making those funds particularly vulnerable to a quantum adversary .
“A successful quantum attack on Bitcoin would result in significant economic disruption and damage across the entire ecosystem,” the proposal warns . “Beyond its impact on price, the ability of miners to provide network security may be significantly impacted” .
The proposal suggests a phased approach to address the risks posed by quantum computers . The first phase suggests stopping people from sending Bitcoin to older, less secure addresses that quantum computers could easily break . The core idea is to implement a mechanism that allows Bitcoin users and the network itself to gradually adopt new, quantum-resistant cryptographic algorithms without disrupting the existing system . This proactive approach ensures that Bitcoin's foundational security remains uncompromised even as quantum technology advances .
The proposal outlines three phases: Phase A would prohibit sending bitcoin to quantum-vulnerable addresses, encouraging the adoption of the post-quantum address type (P2QRH) . Phase B, expected to activate two years after phase A, would make all ECDSA/Schnorr based transactions invalid, effectively freezing any funds that haven't been migrated . Phase C, which remains optional and subject to further research, may offer a recovery path with a proof of possession of a corresponding BIP-39 seed phrase .
The proposal warns that roughly 25% of all bitcoin have exposed public keys on-chain, making them vulnerable to quantum theft . By blocking new transactions to quantum-vulnerable addresses, the proposal aims to reduce the future attack surface with each new UTXO created .
Jameson Lopp, CTO and co-founder of the self-custody platform Casa, along with five other developers, has proposed new strategies to counter the potential threat of quantum computing . Their proposal aims to steer Bitcoin holders to adopt more secure, quantum-resistant storage methods and implement additional protective measures .
Many experts believe that practical quantum attacks are decades away . Cryptography research group ECRYPT II projected that 256-bit ECC (like Bitcoin's) is secure until at least 2030–2040 .