Over 6 Million Bitcoin, Including Satoshi's Holdings, Vulnerable to Quantum Attacks Without Post-Quantum Wallet Migration

A prominent figure in the cryptocurrency space has issued a stark warning regarding the future security of early Bitcoin holdings against emerging quantum computing threats. Tom Howard, a Zcash Community Grants candidate with a background in computer science and venture capital, stated that "even if BTC upgrades, the Satoshi million are vulnerable to quantum attacks if they aren't moved to a PQ wallet." This highlights a critical vulnerability for a significant portion of the pioneering cryptocurrency's supply.

Quantum computers, leveraging algorithms like Shor's, pose a theoretical threat to Bitcoin's current cryptographic foundation, the Elliptic Curve Digital Signature Algorithm (ECDSA). These advanced machines could efficiently derive private keys from public keys, compromising the security of funds. While not an immediate concern, experts predict that cryptographically relevant quantum computers could emerge shortly after 2030, or within the next 5 to 15 years, accelerating the urgency for preventative measures.

The primary vulnerability lies in early Bitcoin addresses, particularly those using the Pay-to-Public-Key (P2PK) format, which directly exposes the public key on the blockchain. Satoshi Nakamoto's estimated 1.1 million Bitcoin are held in such addresses. Additionally, Pay-to-Public-Key-Hash (P2PKH) addresses become vulnerable if they are reused after a transaction, as this also reveals the public key. This exposure enables "harvest now, decrypt later" attacks, where adversaries collect public keys today for future decryption.

A 2025 Human Rights Foundation report indicates that approximately 6.51 million BTC are vulnerable to such quantum attacks. Of these, 1.72 million BTC, including Satoshi's stash, are considered lost or unmovable, while another 4.49 million BTC could be secured through migration. This substantial amount represents a significant portion of Bitcoin's total supply, potentially impacting market stability and user confidence if exploited.

The cryptocurrency community is actively exploring solutions, primarily through post-quantum cryptography (PQC). Organizations like the National Institute of Standards and Technology (NIST) have standardized quantum-resistant algorithms such as CRYSTALS-Kyber and Dilithium. Implementing these into Bitcoin would necessitate a network-wide upgrade, likely a soft fork, requiring users to voluntarily transfer their funds to new, quantum-resistant address types.

Tom Howard emphasized that "Quantum compute is coming faster than we expected and the Zcash system naturally lends itself to quantum resistant cryptography where Bitcoin does not." This suggests that while all cryptocurrencies face this challenge, some may have a more straightforward path to adopting quantum-resistant solutions. The ongoing development and implementation of PQC are crucial steps to safeguard the digital asset ecosystem against this evolving technological threat.