Bitcoin Q-Day Is Getting Closer, Casa CEO Lopp Warns
Lopp says the quantum threat to Bitcoin is not immediate, but warns that moving to quantum-safe signatures could take years.
Key Takeaways
- Casa CEO Jameson Lopp warns that Bitcoin is not immediately vulnerable to quantum computers, but that preparation is lagging behind.
- About 2.6 million BTC sit in addresses that may never be moved to quantum-safe cryptography.
- Lopp supports BIP-361 to phase out quantum-vulnerable signatures over time, while a full upgrade could take five to 15 years.
Casa CEO Jameson Lopp says a quantum computer that can break Bitcoin is still far off, but he also warns that preparation for that threat is already behind schedule. In his view, the crypto market is not facing an immediate problem here, but it is facing a technical and governance issue that cannot be put off.
Why Q-Day Matters
The debate centers on about 2.6 million BTC, worth roughly $207 billion (€185 billion), sitting in addresses that may never be moved to quantum-safe cryptography. That makes the topic relevant for anyone following Bitcoin long term, especially since many addresses have already left a public key trail behind. In that scenario, an attacker could in theory later try to misuse data collected earlier.
Lopp points out that Bitcoin would mainly be vulnerable through its elliptic curve signatures, not through the SHA-256 hashing used in mining. The gap between today’s state of the art and a computer that can break Bitcoin signatures is still enormous, he says. Google’s Willow chip runs on 105 qubits, while Google estimated in March that fewer than 500,000 qubits would be needed to crack Bitcoin signatures.
The Deadline Is Still Debated
Not everyone sees the same timeline. Stefano Gogioso, a quantum computing lecturer at Oxford and co-founder of Spooqy, places Q-Day in the early to mid-2030s instead. He defines Q-Day as the moment when Bitcoin’s secp256k1 curve can be broken within one block, or about 10 minutes.
Lopp calls that estimate a reason to start planning now. He helped work on BIP-361, a proposal to phase out quantum-vulnerable signatures over several years. In his view, there would only be real pressure to activate it once a capable quantum computer seems less than 10 years away. At the same time, the migration itself is slow: Chaincode Labs estimates a full upgrade could take five to 15 years.
Why This Matters for Bitcoin Holders
The core issue is not just technology, but coordination too. Bitcoin does not have a formal governance structure that can quickly push through a network-wide change, while a new signature standard would need broad support to keep the network usable. That makes the timing of a migration more important than just whether quantum computers are already strong enough today.
Lopp says the problem is not urgent in the sense that users need to panic today. But it is urgent because decentralized systems have to make hard choices before an emergency hits. Coinbase, which Lopp says holds about 12% of all BTC, already published a quantum preparedness plan in October, but there is still no agreed deadline for the protocol itself. Coinbase’s earlier proposal for quantum preparedness also focused on a phased migration of wallets and signatures, precisely because a sudden switch would be difficult for the network.
