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Points of Focus
- Smith said a fast quantum advance could push capital from crypto into gold or bonds.
- CSIS said US banks face no supervisory quantum deadline, contrary to Smith’s claim.
- Quantus’ hashrate was 24 TH/s on Sept. 30, against Bitcoin’s 962 EH/s on Oct. 6.
Google Quantum AI said on March 31 that breaking 256-bit elliptic curve cryptography could take fewer than 500,000 physical qubits and a few minutes, a roughly 20-fold qubit reduction, and it cited a 2029 post-quantum migration timeline.
Grayscale Research's analysis of the @Google Quantum AI paper suggests breakthroughs may come in sudden leaps, not gradual steps. That means preparation can’t be delayed.
The good news:
• Post-quantum cryptography already exists
• Some chains like $SOL and $XRP Ledger are… pic.twitter.com/r5vtnnWCJj— Grayscale (@Grayscale) April 6, 2026
Bitcoin’s response so far is Bitcoin Improvement Proposal (BIP) 360, which adds a new output type but no post-quantum signatures, and no activation date has been announced.
Chris Smith, co-founder and CEO of Quantus — a post-quantum proof-of-work chain whose mainnet launched on Sept. 9 — argues the cost of delay is capital leaving crypto, not Bitcoin breaking. In a conversation with AlphaWire at Token2049 Singapore, Smith said a fast quantum advance would not stop at Bitcoin.
Quantum capital flight risk for crypto
“If it happens too quickly, a lot of capital is going to leave crypto altogether,” Smith said. “There’s essentially $3 trillion at risk right now, and there are not that many places for it to go.” He expects holders to move into gold or bonds and rejected the view that Bitcoin’s failure would be the least of anyone’s problems.
If he were an attacker choosing a blockchain key, he would pick Tether’s. “Out of the blockchain keys, the first one I would choose would probably be the admin key for USD Tether,” Smith said, describing a scenario of minting, depegging, and lost trust in stablecoins.
Bitcoin quantum migration and block size limits
Smith said he is most concerned about Bitcoin. “I’m more optimistic about the other blockchains. I’m most concerned about Bitcoin,” he said. A post-quantum address type is not hard technically and could land within months given enough public support, he argued. Still, migration is harder because small blocks already cap throughput, and larger keys and signatures would cut it further.
“Cryptographers have known for 30 years that eventually, elliptic curves were going to fall to quantum computers. But we built the whole blockchain industry on top of elliptic curves anyway,” Smith said, calling it technical debt.
Neither Bitcoin proposal has an announced activation date. BIP-361 would phase out ECDSA/Schnorr signatures and permanently freeze funds left in legacy addresses. Adam Back said in November 2025 that a meaningful threat is probably 20-40 years away.
Banks, SWIFT, and post-quantum deadlines
Smith pointed to finance as proof the shift is coming, saying banks are already updating, SWIFT releases a post-quantum version next year, and US banks face a government deadline. CSIS says federal high-value systems face a 2030-2031 clock under executive order 14412 and OMB M-26-15, but supervised banks have no equivalent deadline. It does put SWIFT’s mandatory Release 8.0 at the end of July 2027, on a post-quantum readiness path.
Consumer software has already moved, Smith said, and users noticed nothing. Apple introduced post-quantum PQ3 for iMessage on Feb. 21, 2024, and Signal added a post-quantum ratchet on Oct. 2, 2025.
Quantus post-quantum mainnet security and Q Day plans
“We’re saving a lot of our ammunition for Q Day,” Smith said, adding that Quantus wants to be established before an emergency so people feel safe migrating.
Its early numbers are small. Quantus put its hashrate at 24 terahashes per second (TH/s) on Sept. 30, with an estimated $45-$80 to mine one QTC and 650-1,100 daily active accounts. Mempool.space shows Bitcoin at 962 exahashes per second (EH/s) on Oct. 6, about 40 million times higher, though the readings are six days apart. The Quantus site lists QTC as coming soon to buy.
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