Whalesbook
Quantum Threat to Bitcoin's Old Addresses
Bitcoin's security is being tested as quantum computing improves. An estimated 1.72 million Bitcoin, worth about $84 billion, are in older address formats potentially vulnerable to quantum computers. These early addresses show public keys on the blockchain, which could let quantum computers figure out the private keys using Shor's algorithm. This threatens dormant funds, especially the roughly 1.1 million BTC linked to Bitcoin creator Satoshi Nakamoto. The challenge is balancing Bitcoin's core value of open, lasting ownership with the need for quantum-proof security.
PACTs: A Privacy-Focused Ownership Proof
Paradigm researcher Dan Robinson has proposed Provable Address-Control Timestamps (PACTs) as an alternative to major network changes. PACTs allow holders of vulnerable addresses to privately prove ownership without moving their Bitcoin or revealing their activity. The system uses BIP-322 signing and OpenTimestamps to create a private ownership record. This record, combined with quantum-resistant STARK proofs, could help users reclaim assets if old addresses are eventually 'frozen' by the network. This approach is more private than proposals like BIP-361, which suggest a five-year window to move funds before they are frozen, potentially forcing owners like Satoshi Nakamoto to reveal themselves.
Key Limitations and Technical Hurdles
However, PACTs cannot help if private keys are permanently lost or if the owner cannot act. If Satoshi Nakamoto or other long-absent owners can't create a PACT, their Bitcoin remains at risk from quantum theft or network freezes. Implementing any quantum-proof solution, especially one requiring broad agreement for a soft fork, is difficult technically and politically. Bitcoin has seen upgrades like SegWit and Taproot, but the quantum threat hits fundamental cryptographic security. Some analysts believe markets have accounted for this risk, giving developers 3-5 years to upgrade. However, newer research suggests quantum computers might arrive sooner, shortening this timeframe. The future requires balancing Bitcoin's original decentralization ideals with the need for advanced security.
Risks of Network Upheaval and Past Issues
Forcing a network change to freeze or 'burn' vulnerable Bitcoin, as suggested in BIP-361, could be seen as 'authoritarian and confiscatory.' Critics argue this violates Bitcoin's principle of open ownership and sets a bad precedent for controlling assets. Such moves could cause major market swings, as investors focus on the idea of intervention rather than just the technical need. While Bitcoin mining's SHA encryption is safe from quantum computers, the elliptic curve cryptography used for transactions could become a key vulnerability. If this causes a loss of trust or drives miners away, Bitcoin's security could collapse. Other solutions, like StarkWare's QSB, offer quantum resistance without a hard fork but might increase transaction fees and complexity.
Development Continues Amidst Uncertainty
Developer interest in quantum resistance has increased significantly, with many conversations happening on mailing lists since mid-2025. Analysts disagree on whether the market has fully factored in the quantum risk, with some pointing to stagnant prices as evidence. The creation of quantum-resistant technologies shows a response to the growing threat. Success will depend on the community agreeing on potential network upgrades and adopting new security standards.