Safeguarding cryptocurrency by disclosing quantum vulnerabilities responsibly

Safeguarding cryptocurrency by disclosing quantum vulnerabilities responsibly(research.google)

88 points by madars 48 days ago | 35 comments

spr-alex 48 days ago |

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.

newpavlov 48 days ago |

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

spr-alex 47 days ago | |

My read of this post is that there's nuance here and that by the time we see 32-bit integers being factored then the roadmap to 256 bit integers can be counted in months on ten fingers rather than being a decade out. The underlying scaling needed to go to 32 bit requires only linear progress to get to 256

newpavlov 47 days ago | | |

>The underlying scaling needed to go to 32 bit requires only linear progress to get to 256

Nope. Firstly, for RSA you need to scale from 32 to 4096. Secondly, Shor requires N^2*log(N) quantum gates where N is number of bits in the integer, so the scaling is superquadratic. And it's very much an open question whether QEC protocols will continue to work with the same efficiency on the required scales.

FrasiertheLion 48 days ago |

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.

PowerElectronix 48 days ago | |

I think the incentive to share progress is still orders of magnitude higher than the incentive to keep it private.

Jarwain 48 days ago | | |

I agree, but I do feel like there's a bit of a lag. The shape of this lag has changed over time, and maybe we're in an era where the lag is growing

ta988 48 days ago | |

You are assuming they have things to hide about QC...

DoctorOetker 48 days ago |

> [...] 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.

tromp 48 days ago | |

I think that "having no known quantum attack" is a reasonable interpretation of "quantum resistant". If there were no possible "quantum attack" (under appropriate complexity assumptions, such as EC-DLP not being in P), then we could call it "quantum proof" instead of quantum resistant.

DoctorOetker 47 days ago | | |

I understand what you mean, but I think such a concept or definition would be highly misleading: "having no known quantum attack" means every novel encryption method would be automatically "quantum resistant" for having had 0 adversarial attempts to find quantum or even classical weaknesses!

There should be some measure of competence-level-adjusted man-hours of cryptographers and mathematicians trying to swing their favorite hammers at the problem; in order to estimate this "quantum resilience".

cma 46 days ago | |

Can't the same be said of classical attacks?

84adam 47 days ago |

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

blitzar 48 days ago |

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.

kevmo314 48 days ago | |

If someone else finds a cryptocurrency vulnerability, they too will reallocate as much of your allocation as they can and cash it out.

bdangubic 47 days ago | | |

often, a mind capable of doing something like this is not the kind that gives a lot of sh*t about things like "money" so I would put a chance of your statement being true at ... 12.78% :)

blitzar 48 days ago | | |

A fool and their money are easily parted.

cinquemb 47 days ago |

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...

nadis 47 days ago |

> "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?).

dandanua 48 days ago |

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?

vessenes 48 days ago |

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.

xnx 47 days ago |

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.