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I was reading a recent Blockstream Research paper on post-quantum Bitcoin signatures. Much of it is deeply technical, but one detail immediately raised my eyebrows:
Schnorr signatures: ~64 bytes
Post-quantum signatures (SPHINCS+): several kilobytes
That matters because Bitcoin fees are simple:
fee ≈ transaction size (vB) × feerate (sat/vB)
A very basic Bitcoin transaction today is ~150 vB.
With post-quantum signatures, that same transaction becomes roughly 3,150 vB — about 20× larger.
Using conservative, “normal” conditions (BTC $70K, 20 sat/vB):
At busier feerates or higher prices, this quickly reaches hundreds of dollars per on-chain transaction.
If BTC is $150K (arguably a fair price today), that becomes $100–$200 per on-chain settlement.
If BTC is $1–3 million, the same math gives $2,000–$5,000 per transaction.
At that point, Bitcoin is no longer meant for casual payments on its base layer — and that’s not a failure.
Bitcoin becomes a global settlement layer.
Moving $1–10 million for a few thousand dollars is still vastly cheaper, faster, and more neutral than moving physical gold between banks or central bank vaults.
Everyday activity naturally moves to Lightning, where transactions remain cheap and instant. Only opening and closing channels touch the Bitcoin blockchain; the payments themselves stay off-chain and low-cost.
The same pressure applies to Ethereum. Larger post-quantum signatures increase data and verification costs, making L2s essential, not optional.
That’s why recent moves around Base matter, why Arbitrum will likely continue as a DeFi hub, and why Linea is interesting to watch given its Ethereum-native design and burn mechanics.
As Bitcoin matures into a credible reserve asset, it naturally becomes something states will hold in their treasuries, not just something markets speculate on.
Once that happens, incentives change in a fundamental way.
Whoever first gains meaningful quantum capability doesn’t just gain power — they also face the largest bounty in history. Exploiting Bitcoin would mean destabilizing an asset that governments, institutions, and allies increasingly rely on.
That creates a powerful counter-incentive: attacking the system harms your own balance sheet and undermines global trust.
In that environment, quantum capability stops being purely offensive and becomes strategic infrastructure.
The next “atomic bomb” isn’t a weapon in the traditional sense — it’s a quantum computer.
And the winners won’t be those who use it recklessly, but those who integrate it into alliances, standards, and resilient global systems.