One key fact about the quantum threat for non-technical crypto investors
Each of us will need to take the last, crucial step to protect our digital assets ahead of Q-Day
It won’t be enough for the blockchains to upgrade and enable quantum-secure wallets that can withstand quantum computers.
Everyone who controls a cryptocurrency address will need to move their assets to a new quantum-secure signature scheme, themselves. Manually.
Uncle Vitalik and Uncle Anatoly can’t move your coins for you, and Uncle Satoshi is gone. This final step is going to fall on everyone who owns a crypto wallet.
The quantum threat is a hot topic, but crypto denizens don’t seem to realize quite how this will come home for each and every one of us.
Further, it’s largely been framed as a Bitcoin problem, but all the biggest blockchains share this issue, to one extent or another. Ethereum, Solana, XRPLedger, Dogecoin… all of them will need to upgrade in some way.
And then every user will need to sign a transaction to move their coins. This is the upshot of “not your keys, not your coins.”
And, collectively, we all need to get this done before a big enough quantum computer powers on.
On the internet, we tend to think of big problems as something we need to urge other people to fix. That’s centralization brain. Once you think through the process of every single owner of cryptocurrency moving their assets to new wallets, you realize that single fact makes it a much more complicated problem.
Self-sovereignty gets tricky.
It’s going to require more than just Bitcoin Core or the Ethereum/Solana/Etcetera Foundation/Labs rolling out a fix. It’s going to require blockspace and organization. It’s going to require everyone digging their hardware wallet out from wherever they hid it.
It’s going to take time.
What is Q-Day?
Look, you probably know this stuff. I’m going to write this section specifically so it’s skippable for people who have read about this topic before, if this is a topic you are already familiar with.
If it’s not, here’s everything a non-technical person actually needs to know.
Cryptocurrency relies on cryptography. In order to make transactions, we need to prove to blockchains that we own the assets with which we want to transact.
To prove that, we send the blockchain a message that says: “I want to send 1 ETH/BTC/SOL to someone else,” and we sign that message with a cryptographic hash that shows that we are really in control of the assets we want to move (this is what your crypto wallet software does for you).
Q-Day is the shorthand for the day that some quantum computer will be able to write a hash for a wallet that it doesn’t control and move assets without the owner’s permission.
As a non-technical person, do you need to care exactly how that works? No.
Plus, it might never even happen! But it probably will. Most technical people think it will.
No one knows when Q-Day will occur, but it looks increasingly likely.
A few years ago we thought it would take a humongous quantum computer to crack the cryptography that protects blockchains like Bitcoin. Then it became merely an enormous quantum computer that’s needed. As of now, we’re down to needing a super big quantum computer, according to Justin Drake, the guy who has thus far led the charge to address quantum computing for Ethereum.
Relative to the requisite size needed to crack the salient cryptography, current quantum computers are still tiny.1
So our quantum computers are getting bigger and better and the size and power of the kind of computer needed to protect our coins is getting smaller. It looks like those two trends will meet one day.
How complicated is the shift
On Bitcoin
At the end of 2024, four researchers at the University of Kent estimated how long it would take for Bitcoiners to transition to quantum-resistant wallets, once we actually have them.2
They estimate that it will require about 76 days of block time on Bitcoin for every wallet to move their coins.
That doesn’t mean that Bitcoin needs to shut down for 76 days straight. It means that it will take 76 days worth of transactions thrown into the mix of its existing transactions to get everything done.
Bitcoin and its peers make us each kings over our own little plots of digital property. It’s good to be king! But kings also have to defend what’s theirs.
Bitcoin, in particular, has limited throughput. Every transaction that gets submitted theoretically competes for blockspace with other transactions proposed around the same time. There’s a finite amount of transactions that can go through every ten minutes. This is why Bitcoin has the Lightning Network, to route around some of these limitations.
This is why I made the joke about herding honey badgers in last week’s news roundup, because it won’t be enough for the network to adopt a new signature scheme. Every Bitcoiner will have to move their coins to a new address.
This means that, first of all, Bitcoiners will need to come to a consensus about the new scheme and deploy it. Any change to the Bitcoin network always takes a long time.
But then every Bitcoiner will need to dig out their hardware wallet and make the move. Alex Pruden, of Project 11, estimated on the ZK Podcast that Bitcoin needs to update to some kind of post-quantum signature scheme two years before Q-Day in order for everyone to get it done.
You know people will procrastinate.
You know blocks will get clogged badly along the way.
And never mind cybercriminals, which I will say a little about further down.
On Ethereum
The Ethereum community made news this weekend when Drake announced that a post-quantum team has been put together, under the leadership of Thomas Coratger.
He announced a number of initiatives that are underway already, including calls with developers and prizes for finding key solutions.
Drake is part of organizing a shift to what he’s talking about as Ethereum 3. This would be an upgrade that would include a number of fixes on the Ethereum roadmap in one giant upgrade. Post-quantum security would be one of the fixes. He’s calling it the Beam Chain (that’s a short video that’s worth watching for anyone on Ethereum — or anyone interested in ambitious plans).
Ethereum may massively upgrade its throughput while dealing with quantum threats and other long-term aims. If that happens, it won’t need to worry about clogging the network nearly as much as Bitcoin does.
Solana
Late last year, the Solana Foundation announced that it was working on a post-quantum signature scheme with Project 11.
And, again, everyone will need to make a transition on Solana. However, Solana’s whole thing is that blockspace is plentiful (unless the chain halts!), so it doesn’t need to worry about a massive traffic jam, like Bitcoin.
For a detailed breakdown on the latest plans on a variety of blockchains, Jung-Hua Liu put together a technical report on where various blockchain communities are at.
Mysten Labs also claims to have found a scheme to protect users on a bunch of newer chains, such as Sui and Near, which is nice for that handful, but they steward a fraction of the value held on the big chains.
Coinbase also announced an advisory board to deal with quantum threats.
Threats
Scammers are going to trick people amidst the transition.
Before too much longer, we’re going to start seeing websites going up claiming to offer post-quantum solutions for fretful crypto investors. We saw this all the time in the initial coin offering era. And we see it now, every time some hot new crypto project teases an airdrop.
These offers will be lies designed to steal people’s crypto assets.
It’s important that influential people in each ecosystem spend a little social capital to educate their followers about these threats, but it’s tough. Social engineers are very good at creating urgency.
Take a breath before you move anything. Check for social validation of any scheme making promises from disinterested third parties.
What can you do now?
The first thing you can do is follow the news about quantum computing developments and blockchain upgrades. You don’t need to follow every twist and turn, you just need to know enough to have a sense if progress has begun to accelerate.
I plan to make it an ongoing topic here, so: stick around.
You can support the social consensus that blockchain researchers need to deal with the issue head on. It seems like that is happening in many crypto communities, but Bitcoin still needs to be nudged along. It’s muddled.
Bitcoin Improvement Proposal 360 seems to be the leading candidate for a fix. Bitcoin legend Jameson Lopp has a proposal, too.
Blockspace Media has been breaking down the technical cutting edge on the biggest and most important crypto network.
Whatever happens: each of us will need to take the final step, no matter how great Bitcoin Core’s solution proves to be.
You can prove what you own. Project 11 has created something called the Yellow Pages, for Bitcoin. It’s a way of anonymously proving that you, a human, control a blockchain address.
With Yellow Pages attestation, you should be able to prove in court that you controlled that wallet before Q-Day. This won’t help you if North Korea robs you, but if it’s snatched by someone reachable with Western law, you might be glad you took the step.
Watch for similar efforts on other chains before long.
You can retreat to an exchange. I think self-custody is the better approach, most of the time, but this will be a strange, once-in-a-lifetime moment (hopefully) for blockchainers. The exchanges have more resources to manage these things than we do as individuals. If Coinbase or Kraken were to announce that they’ve got a quantum-secure storage scheme ready, it might make sense to try that.
TL;dr — leave it to Uncle Brian till the dust settles.
That might be a good hedge for people who don’t move assets around very often, and you don’t have to move everything over to a custodian, anyway.
This is a very personal decision, though, depending on your threat model. It’s not like exchanges have a perfect track record, though the American exchanges have been very, very good.
The key point here is that every single wallet owner on all the biggest blockchains is going to need to move their assets to a new, post-quantum address. Tell your crypto friends. I really don’t think the average investor gets this yet.
The chains can’t do this for us.
Because we each actually really own and control our digital assets, it’s also our responsibility to move them when the threat landscape changes.
Bitcoin and its peers make us each kings over our own little plots of digital property. It’s good to be king! But kings also have to defend what’s theirs.
The latest estimate Drake gives is about 400,000 qubits (the smallest unit of a quantum computer) to break the cryptography of most blockchains. The biggest ones working these days are around 6,000 qubits, so less than 2% the requisite size at present.
Downtime Required for Bitcoin Quantum-Safety, by Jamie J. Pont, Joseph J. Kearney, Jack Moyler, Carlos A. Perez-Delgado.