"When you don't have a need for a cryptographic digest, it's important to think of the channel's bit error distribution in selecting a checksum algorithm."
Important real-life-facts.
There was no "give-me-an-appropriate-hash" function.
There was:
md5sum yourfile.txt
Nobody wants to think about "channel's bit error distribution" in a non-security critical context. In fact, its irrelevant, and possibly a usability issue.
MD5 has/had a well-known "media" surface - lawyers/genomics folks had heard of it. Libraries had it as an accessible function (command line utilities, even).
Sure, there are better non-cryptographic hashes, but, again the concern of lawyers and genomics folk is neither security nor efficiency - simplicity and "works most of the time" are the two metrics at stake.
If either laywers or genomics folks cared about document forgery of this nature (spoiler, they don't), they would move to something like SHA3. If they had a need for high-scalability hash algorithms (spoiler, they don't), they would switch to another faster algorithm.
This is a concept I understand security folks struggle to understand - sometimes we _just don't care_. And we never should.
Maybe, something a struggling security enthusiast could understand - a video game.
If you implement e.g. a caesar cipher, you can have fun, accessible puzzle. Implementing AES in your game as a puzzle, while much harder, fails desperately at the "accessibility" metric. In your single player game, if you want to see some "identifying hash", if you see an md5 one, that's enough. No, you should not worry about people forging documents for your ad-hoc identification system, if you don't have people attempting to forge in-game items. Maybe its even a feature that you need to forge such a hash, as a way to solve a puzzle.
I am curious as to your perspective as a physicist, do you think it is feasible to have a QC computer from an energy perspective?
There is the cost to consider, yes, there is also an energy cost to a stable QC system. Asymmetric/symmetric are not unbeatable, they have an energy cost. Shors algorithm is theoretically great, but rarely if ever have I seen an associated energy cost...even outside of the answer "will we build one" the question is "can you efficiently build one" or not, i.e. what does a QC capable of executing shor's algorithm look like, a small planet or star perhaps?
So, as nickelpro states, I feel like a QC that is actually general purpose (which is probably a better way to state it) is so difficult at this point to even imagine, it's hard to say it will become a thing absent some breakthrough that is hereto unknown. You probably could state it as an energy cost thing by somehow deriving how much energy it would take to keep millions of quibits from decohering by extrapolating from how much energy it takes to keep a few from decohering, but I'm not even sure you can extrapolate that far out since as you increase the number of quibits the required energy probably isn't linearly related to the number of quibits but it is some power law or worse. Remember, the number of quibits we can run is in the dozens today, the numbers you need for Shor's algo or just general purpose computing is likely in the millions.
For quantum people, the QCs are already pretty cool because they can do simulations of quantum systems like molecules and atoms that are just infeasible on classical computing (high performance computing, ie. supercomputer) systems, things that would take probably years (yes years) of wall time on a HPC system. The thing is the number of required quibits for modeling these types of molecules is likely in the dozens to 100+ quibits, which looks possible now since there are systems out there that, while noisy, do have dozens of operating quibits.
If you're curious what these simulations are for, it's doing things like calculating energy levels for certain molecules, which materials science people care about and will help them make the next generation subtrate for a computer chips, etc etc. So it's not entirely esoteric stuff, it will be things which will eventually make it into actual products and technology people use, but it definitely is NOT general purpose computing, even less so Shor's algorithm or breaking encryption.
Could I boost it to 2-5x time with a simple JS script? Sure. However I figured rate limits were in place/that wasn't the spirit of...whatever this is.
Reminds me of Peter Molyneux's Curiousity: https://en.wikipedia.org/wiki/Curiosity%3A_What%27s_Inside_t...