Would the counter to this be to create giga/tera/peta-bytes of encrypted junk files left in suitably mis-secured servers connected to the internet. You may not be able to stop the Chinese gov from hacking and obtaining data but you can make the indefinite storage of it pretty hard. Also if it’s encrypted gibberish, would that slow down the decryption of it? After all if an unencrypted file appears to be random data, then it hasn’t been decrypted properly, so back to the code breakers it goes, wasting more resources. A sort of data Cold War.

An interesting question: when you are brute-forcing something, how do you know when to stop?

When you've tried all possibilities — it's like trying all combinations on a luggage lock.

Or sooner if the result seems to make sense. I vaguely remember that some researchers reported an ability to encrypt in a way that could yield more than one apprently valid decrypt. Does anyone here have a reference to this?

It's a defining feature of one-time pads. Given the right key, you can literally get anything out within the size limit.

Essentially by looking for cues that you know in the answer - hopefully I've posted the right youtube thing (I have no association with this, just found it interesting), but it explains how you can start pruning your decryption search until you get something meaningful.

https://www.youtube.com/watch?v=RzWB5jL5RX0

Rather than actually generate and store, just simulate a file system and generate the random stuff when an intruder "reads" it. The cost of storage then falls entirely on the intruder. For bonus points simulate an entire network. Let them keep "discovering" another server full of stuff.

I know that quantum computers are theoretically able to decrypt some encryption methods, because they can factorize large numbers. But I thought there were different encryption methods which didn't use large number factorization, was it elliptic functions? Doesn't that mean that we could switch to those methods and quantum computers would stop being such a bogeyman for encryption?

How close are quantum computers to be of any use anyway? Because they often seem to be predicted for right after fusion reactors, or whenever half life 3 is released, whichever happens last...

It nice to know the Chinese have bought in to the quantum snake oil, jut like everyone else.

"It nice to know the Chinese have bought in to the quantum snake oil, jut like everyone else."

You've got a point there. A bit of skepticism is probably appropriate. On the other hand, China (and US and EU and ...) probably can't afford not to assume that quantum or other advanced decryption techniques might become available at some future time.

How close are quantum computers to be of any use anyway

Depend on what you want to do. Quantum computing uses Shor's algorithm to factorise integers.

The current highest number factorised this way is 21, they tried to factorise 35 but failed because of accumulating errors.

So if your requirements are factorising small numbers then they are ready to go. If you actually want to do something useful then probably not for a long time, if ever.

Of course if something better and more fault tolerant than Shor's comes along then it may all change overnight.

That's just what we know, though. Don't rule out black projects.

Shor's algorithm works for attacking elliptic curves, as used in ECDHE or ECDSA, just fine.

You'd need to switch to supersingular elliptic curves to be secure against quantum computers. But the current most likely winner is lattice based crypto.

What if its encrypted using quantum encryption then is it not possible to tell if its being hacked because of entanglement?

Once the middle kingdom has the quantum computing capability its a fair assumption that uncle sam will too.

We can't assume that America will be able to keep up - China has way more engineers because they're working hard to give everyone with the ability the opportunity to learn for free, while America's increasingly expensive education system means only those with existing wealth or willing to commit to a lifetime of debt can afford to train.

Even turning everything around now would not be enough to catch up by this point- China has already won the 21st century from a technology perspective.

Yep!

https://en.wikipedia.org/wiki/Post-quantum_cryptography

We're a long long way from having decent quantum computers, they're still in the research phase now. Workable qubits are in the hundreds at the moment and I've heard an estimate that you need about a million for anything useful. And you still need to 'program' them, which is non-trivial. There may be a breakthrough in tech, but like you say, future quantum computers should be powered by fusion!

And its standard practice to harvest data and hope to decrypt it in the future, although you're making your haystack bigger with a potentially rusty needle in it.

All they have to do is put on embargo on exports to Amazon and the West will be brought to it's knees.

If they did it today it would be like murdering Santa - goodby Christmas!

Given most of the hardware the rest of the world uses is made in China, "oh that? yeah we deciphered it with quantums" might make for a good cover if anyone found them using data that should have been securely encrypted without giving away any spy-in-the-hardware type systems they have slipped into people's chips, motherboards, memory, graphics cards etc &co. A side benefit being that it would make it look like they had way more quantums than anyone else which would probably America to work much harder on that, knowing that if the US makes any big breakthroughs that are practical to turn into products they'd probably have them manufactured in China.

so we can safely assume the Americans have this program well in hand.

so we can safely assume the Americans have this program well in hand. ..... cantankerous swineherd

A question to ponder and wonder at, for it may be considered too awesome to answer correctly and truthfully, is does China [and therefore the East] lead in that other emerged quantum domain/those other developing fields with applications exercising and advanced beta testing Deep See Ware fare ..... with IT forks into AIMindfulness .... or does the West assume and presume to be a primary leader worth following via mass multi media tales in that field too ‽ .

Mostly the dangers that Booz Allen are reporting on are a list of all of China's naughtyness over the last few months that have been reworked to sound as though they can relate to 'quantum'.

Quantum computers, fusion, flying cars and robo-butlers will all be possible around the same time (pick a repeating number i.e. decade, twentyfive years, blah blah.

I imagine that anyone who has come by some unencryptable data has stuck it in a drawer marked quantum.

TLAs all round the world have been hoovering up raw data for decades in the hope that sooner or later they'll be able to decrypt it (and hope it's still useful by then).

Adding "Quantum!" to this doesn't make it news.