Quantum Computing and Bitcoin: What to Check Today

In an interview reported on October 3, 2026, VanEck's head of digital asset research, Matthew Sigel, called Bitcoin quantum risk a long-term risk worth watching that does not yet justify selling, according to TokenPost's summary of the interview. His comments land while Bitcoin developers keep working on BIP-360, a proposal for a new output type that cuts long-term exposure to quantum attacks. The risk is real and it is not urgent. The hard part is working out what that means for your own coins, so take it one step at a time.

Step One: Size Up the Real Bitcoin Quantum Risk

Breaking the elliptic curve cryptography behind a Bitcoin signature takes a specific machine, not just "a big quantum computer." In March 2026, Google Quantum AI's whitepaper estimated the job at fewer than 1,200 to 1,450 error-corrected logical qubits, which it put at under half a million physical qubits running at low error rates. That was about a twentyfold drop from earlier estimates, and it is the reason the topic got louder this year. No publicly announced machine comes close to that size at those error rates today. Sigel's framing, long-term rather than immediate, matches the hardware.

Step Two: Learn What Exposes a Bitcoin Address

A quantum attack needs your public key, and Bitcoin output types differ in when they reveal it. Hash-based addresses, the ones starting with "1" (P2PKH) or "bc1q" (P2WPKH), store only a hash of the key and reveal the key itself when you spend. Two kinds of coins have their keys out in the open for good: the earliest pay-to-public-key outputs, Satoshi-era coins included, and any address you reused after spending from it. Taproot addresses, the ones starting with "bc1p," also place a public key in the output itself. Estimates published this year put roughly 6.5 to 6.9 million BTC in outputs with exposed keys.

Google's paper adds a caveat worth knowing. A fast enough machine could attack a key in the minutes a transaction waits in the mempool, which would reach every standard address type. A hash-based address that has never spent makes you a smaller target, not a safe one.

Step Three: Check Your Own Bitcoin Address Exposure

You can act on this step today. Look up each address you hold coins in on a block explorer and note two things: the address prefix, and whether it has ever sent a transaction. If it starts with "1" or "bc1q" and has only received, its key has not been revealed. If it has sent before and still holds coins, or it starts with "bc1p," the key is already public. The fix is old self-custody hygiene: move the coins to a fresh "bc1q" address you have never used, and stop reusing addresses. None of this needs a quantum computer to exist before it pays off.

A hardware wallet makes this easier than it sounds. Most current wallets generate a new receive address every time you ask for one, and spend change to another fresh address, so the reuse problem comes mostly from old habits: an address printed on a donation page, a single address pasted into an exchange withdrawal for years, or a mining payout address you set once in 2021 and never touched. Those are the ones to find first, because each spend from them left the key on the chain.

Step Four: Understand Where BIP-360 Stands

BIP-360 defines a new output type, Pay-to-Merkle-Root, that keeps Taproot's script tree and removes the key-path spend, so an output no longer puts a public key on the chain. On its own it adds no post-quantum signature scheme; it builds the structure that a later signature upgrade could plug into. It has not activated on mainnet. You cannot move coins into a quantum-resistant address today, because the soft fork that would create one has not happened. Any product that tells you otherwise is ahead of the protocol.

What This Means for Mining Specifically

A found block still pays a solo miner the way it always has: the coinbase transaction pays whatever address you set. The Payout Preflight tool on nexuspool.io shows that coinbase before you find a block, built on today's address formats, because those are what the network runs. Step Three applies to a mining payout address too. Point your miner at a hash-based address you use for nothing else, sweep it to a fresh one when you spend, and you close the long-term exposure quantum risk could someday reach.

NexusPool's technology page covers what the pool holds, which is nothing: 0% fee, and the block reward paid straight to the miner's own address, with no pool wallet for any attacker, quantum-equipped or not, to target. The Glass Ledger signs an hourly receipt for the shares the pool counted from your rig; it relies on today's signatures like everything else on the network. None of this makes NexusPool, or Bitcoin, quantum-resistant today. Neither is, and quantum risk does not change your odds of finding a block, which come from your hashrate against network difficulty at any pool.

The Four Steps, Compressed

Know the hardware gap before you react to a headline. Learn that exposure depends on address type and reuse. Check your own addresses today, since it costs nothing and takes minutes. And treat BIP-360 as a serious step toward a fix that you cannot use yet. If you do one thing, do the address check: it gives you a concrete answer this afternoon, long before any quantum computer exists that could use what it finds.

Trust nothing. Verify whether your own address has ever exposed its public key before you decide this risk doesn't apply to you.