[exmadscientist]

Would anyone downvoting care to explain? I'm genuinely interested in seeing anything that suggests there's either some secret breakthrough (completely plausible, but there's no evidence that I've seen hint of) making quantum computers actually useful, or an argument that they'll be usable by (say) 2050?

Because right now my attitudes are trained by things like this https://algassert.com/post/2500 that explain just why 15 was factored in that famous run of Shor's algorithm and not, say, 21; and why 21 hasn't been factored yet and isn't likely to be any time soon....

[alphager]

I work as a security architect in a major European company. We're currently demanding a full cryptographic inventory of every new product purchased or service built in-house and will start demanding PQC in 2028.

Not because we expect a workable quantum computer by 2030 (current estimates are around 2035-2040), but because stuff survives for decades in large enterprises (especially if it touches hardware in any way. Think OT, think controllers for all kinds of machines).

Now that PQC is standardized, there's no gain not to demand it (it's basically a demand to use a current openSSL/libreSSL/$library), but not demanding it now will cause a major headache once/if quantum computers work.

TLS connection speed matter only for a very tiny niche of applications; those will choose according to their needs. For the general case, it just doesn't matter.

If your threat model includes store-now-decrypt-later, you should have been demanding PQC for years.

[plopilop]

Man, the CBOM is such a pain. There is no standardised format yet (let alone efficient tools for crypto discovery), nobody knew what it was one year ago but now every client is asking ours anyway.

[dredmorbius]

CBOM: Cryptography bill of materials.

<https://cyclonedx.org/capabilities/cbom/>

[alphager]

Tell me about it! We've got slightly under 10'000 distinct software assets we are trying to catalogue. There are now a handful of vendors claiming to be able to scan for crypto, but they all suck.

[plopilop]

I'm not even there for my employer. I have compiled a list of ~20 different inventory/CBOM solutions and I cannot even fathom how to move to the next step other than picking a few vendors at random and ask them for a demo, but the public info I found was not convincing.

While I can assume these tools do a decent job at crypto asset discovery (a `grep -r "-----BEGIN RSA PRIVATE KEY-----"` is not the hardest product to design), I have no idea what to do for code scanning. CBOMkit and friends do not scan C code, which we actually need.

[plopilop]

There has been a lot of new stuff over the last few years.

For instance, breaking RSA or ECDSA is requiring much fewer logical qubits than previously thought, and thus fewer physical qubits as well. Progress in error codes, quantum processing etc. made it that in 2019, it was estimated we needed ~20 million noisy qubits to factor RSA 2048. In 2025, we know we need fewer than 1 million. [0]. Some other papers even claim the need of 1000 physical qubits but they rely on a very exotic architecture so I would not consider them feasible.

Progress on the hardware is also continuing, see [1]. Researchers managed to have functional-ish error correction for the first time last year, and experts in the topic are confident that a cryptographically relevant computer will appear in around 15 years.

I personally am less optimistic than the experts (admittedly I am not an expert either), but there is enough activity to get worried for critical infrastructure.

Regarding the factoring issue, as you point out factoring 15 and factoring 21 are two very different tasks. The first one can be used to show that your quantum computer is indeed doing quantum computation; the second will prove that you have a functional error correcting code. If you can factor 21, it is probably only a matter of months/maybe a few years until you factor RSA 2048. As Scott Aaronson said [3], "Once you understand quantum fault-tolerance, asking “so when are you going to factor 35 with Shor’s algorithm?” becomes sort of like asking the Manhattan Project physicists in 1943, “so when are you going to produce at least a small nuclear explosion?”"

[0] https://arxiv.org/abs/2505.15917

[1] https://sam-jaques.appspot.com/quantum_landscape

[2] https://globalriskinstitute.org/publication/quantum-threat-t...

[3] https://scottaaronson.blog/?p=9665#comment-2029013

[pixl97]

When you're a fully loaded freight train running at full speed you have to hit your brakes miles before the collapsed bridge. It's way easier to switch to another line that is intact when you have the opportunity instead of in a panic.

[krisbolton]

Google and Cloudflare recently moved their PQC migration timelines forward based on recent research papers in the field. Sources: 1. https://blog.google/innovation-and-ai/technology/safety-secu... 2. https://blog.cloudflare.com/post-quantum-roadmap/