Safeguarding cryptocurrency by disclosing quantum vulnerabilities responsibly (opens in new tab)

Beware the Ides of march: this is 1 of 2 cryptographic doom papers that was released this week. This google paper with Babbush, Gidney, Boneh is authoritative. And we also have another with Preskill and Hsin-Yuan Huang (widely cited for classical shadows among other quantum work) among others: https://arxiv.org/pdf/2603.28627

"Here, by leveraging advances in high-rate quantum error-correcting codes, efficient logical instruction sets, and circuit design, we show that Shor’s algorithm can be executed at cryptographically relevant scales with as few as 10,000 reconfigurable atomic qubits. "

That's physical, not logical qubits.

Have they factored 21 yet? [0] IMO most of us can ignore such pieces until a practical factorization of arbitrary 32 bit integers is demonstrated on a QC. And even after this "easy" milestone is achieved, I think it will be at least a decade until QC will be a practical cryptographic threat. And it's generously assuming that a Moore-like scaling is possible for QC.

[0]: https://algassert.com/post/2500

It's unfortunate that we're past the point where all quantum computing progress is public. Between this and the unbearable secrecy of AI labs, balkanization of knowledge is in full force.

> [...] including transitioning blockchains to post-quantum cryptography (PQC), which is resistant to quantum attacks.

PQC is not defined as "being resistant to quantum attacks" nor does it necessarily have this property: PQC is just cryptography for which no quantum attack is known yet (for example even when no one has tried to design a quantum computation to break the cryptography). One can not demonstrate that a specific PQC altorithm is resistant to quantum attacks, it is merely presumed until proven otherwise.

I have compiled some notes about these recent announcements here, as it pertains to ECC and Bitcoin.

Note: There are specific address types that are safer to use for long-term storage than others, such as Native SegWit addresses starting with `bc1q`. The newest Taproot type starting with `bc1p` is insecure because it directly encodes a "tweaked" public key into the addresses.

https://bc1984.com/quantum-feasibility

If I find a cryptocurrency vulnerability I am reallocating (the blockchain never lies) as much of it as I can and cashing it out.

Its the only responsible thing to do.

Pretty much all of quantum control right now is based on the idea that qubits are these fragile things that have to be corrected, but thats because poor assumptions for quantum control are used (SO(3) precession). And even when they are treated like open quantum systems (like everything naturally is, even at 10mK and 10^-11 Torr), stuff like linblad master equations are used which is based on born-markov assumption that the env is a memoryless bath... when one stops using these poor assumptions and treat the system as a dynamical object that has natural states of stability that dont need to be actively corrected... these crypto breaking alarms are going to seem very tame.

This also has implications for alot of PQC and QKD stuff that's based on static model assumptions...

> "Quantum computers promise to solve otherwise impossible problems, including examples in chemistry, drug discovery, and energy. However, large-scale cryptographically relevant quantum computers (CRQCs) will also be able to break current, widely used public-key cryptography that protects things like people’s confidential information. Governments and others, including Google, have been preparing for this security challenge for many years. With continued scientific and technological progress, CRQCs are getting closer to reality, requiring a transition to PQC, which is why we recently introduced our 2029 migration timeline."

Is this as wild a news as I think it is? I'm surprised I haven't yet seen more reactions to the 2029 migration timeline plan (proposed?).

Why do they care about cryptocurrencies but not about the entire world's infrastructures that are based on RSA and elliptic curve algorithms, such as HTTPS and many other electronic signature solutions? Is this a case of cryptocurrency market manipulation?

And why do they think that the US government would care about securing cryptocurrencies? Aren't they designed to circumvent the government regulation?

I haven't seriously looked at Bitcoin's PQ plan for a couple of years, so I might be (I am almost certainly) out of date, but my recollection is that there's a "pre working attack" phase required, in which everyone basically signs a new PQ secure address, and a cutoff date.

This would leave holders who did not sign in two categories:

1) If you never sent a tx with an address, then you did not reveal your public key, and have some safety, e.g. you could do the PQ signature, wait, and be fine.

2) If you did, then you revealed your public key, and didn't bother to make the cutoff, and well, too bad.

There was a bunch of frankly dumb analysis about how long this would take the chain to process and how expensive it would be assuming that miners would all continue to enforce 10 minute blocks and transaction fees for these signature txs. I would be very surprised if the mining industry shot itself in the foot like that. The actual time to process 200mm or so new signatures just isn't that long. Hey we could do it on Solana if we needed to. That said, I imagine the papers this week plus Google moving up its timeline mean that there will be a concerted effort in Bitcoin land to get a real process down and tested in the next couple of years. Pretty cool.

Finally, I've read very little analysis about whether or not miners would choose to continue the energy dependent nature of mining, or try and move on. I think this is a pretty interesting economic question; I'm looking forward to finding out the answer. I expect mining will have a longer lead time than the signature problem - we're a long way from having Grover implementing SHA-256 as far as I know. And even then you still have 128 bits to deal with ONCE you get an equivalent amount of Grover-capable quantum compute out to the current ASIC ecosystem.

A few blog posts from Google's Quantum team recently make it seem they are confidently on the path to cracking traditional cryptography. Real Setec Astronomy stuff.