Galaxy research head Alex Thorn said in a recent report that quantum computing poses a real risk to Bitcoin, but the technology is still years—possibly decades—away from breaking ECDSA, the cryptographic signature system at the center of Bitcoin security. Today’s machines do not have the logical qubit capacity needed for that task. For now, the threat remains mostly theoretical. The market is acting that way too, with Bitcoin still trading around $70,000 and institutional participants showing little visible stress tied to quantum developments.
Older Bitcoin addresses face the greatest exposure
The report says the quantum risk is uneven across the network. Wallets from Bitcoin’s early years, especially repeated-use addresses and some unspent transaction outputs from the Satoshi-era period, are more exposed because their public keys are already visible on-chain. If quantum hardware reached the required level, those addresses would stand closer to the front of the line.
Modern P2PKH addresses offer a different security profile. Their public keys are only revealed when a transaction is broadcast, which means an attacker would need to intercept and act on that key before the transfer is completed. That makes exploitation harder. The report adds that the assets sitting in those older address formats remain an open question, including whether they will ever be moved into quantum-resistant structures.
Bitcoin developers are already studying migration options
According to the report, Bitcoin developers are not ignoring the issue. Research into post-quantum cryptography is already underway. The Taproot upgrade in 2021 created technical room for more complex scripting, which could support future signature systems such as Lamport or Winternitz, both widely viewed as candidates for quantum-resistant designs.
The report says a future soft fork could become the mechanism for moving users toward new quantum-secure addresses. Thorn compares that idea to Bitcoin’s long transition from legacy addresses to SegWit, a process that took years. In a quantum migration, the consequences would be more severe and the timing pressure could be tighter. Bitcoin’s slow upgrade culture remains a security choice as much as a practical limitation. The report also notes that Ethereum is moving faster on its quantum-security roadmap, and that progress may offer a reference point for other blockchain networks.
“Harvest now, decrypt later” remains a separate concern
Thorn also pointed to a less discussed quantum scenario: state-level actors could collect encrypted communications today and wait to decrypt them once quantum systems become strong enough. That creates a serious threat for private communications and sensitive data. Bitcoin is different because balances are openly visible, so the direct near-term effect is smaller.
Even so, the report warns that by the time quantum computers are publicly recognized as powerful enough, the chance to secure the most vulnerable Bitcoin addresses may already be gone. IBM and Google have made notable progress in quantum error correction, yet market pricing still centers on nearer-term developments. Long-horizon technical risks such as quantum computing have not been meaningfully absorbed into current valuations.