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Cake day: February 1st, 2023

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  • A quantum computer doesn’t just calculate every possibility simultaneously, it’s much more limited. It “calculates more things at once” in some cases.

    Generally speaking, some things that are hard for a regular computer are easy quantum computers. So if an encryption algorithm is based on the difficulty of those things (e.g. RSA is based on the difficulty of factoring a semiprime number), and the thing is easy for a quantum computer (e.g. factoring a semiprime), then you could defeat the algorithm with a quantum computer.

    How do you protect yourself? You base the algorithm on something that is difficult for both a regular and quantum computer, that’s what post-quantum algorithms do.

    But quantum computers have one last ace up their sleeve. There is a sure-fire algorithm (Grover’s algorithm) to speed up any situation where you need to find an unknown value of a known length (in this case the secret key). To keep it simple, if to find the key a traditional computer would need N steps (because there are N possible keys), a quantum computer would need just √N, which is much less. Now, this sounds massive, and it is, but if you consider that with M bits there are 2^M keys, then if you just need to check √(2^M) keys, it’s like using keys of M/2 bits, so to defend against this you just need to make the key twice as long.

    Lastly, as a footnote: quantum computers can be faster than regular computers, but strictly speaking, regular computers are more powerful, that is to say they can do more things. We say that traditional computers are turing-complete, which means that they can compute anything that is computable, that is not the case for quantum computers, which means that some things (even easy things) that a computer can do, cannot be done on a quantum computer. For example, there is no way to implement regular expressions in quantum computers, it’s impossible. I know regex look difficult, but in computation theory they are among the easiest things a computer can do.

    Edit: one quick addition to the paragraph about Grover’s algorithm. If a quantum computer really just tried all the solutions at once it would be much faster than that. It would be (may my professor forgive me for saying this) “like if it guessed the bits of the key one at a time and were right on the first try”, so if you had your M bits key, you would need just M steps instead of the 2^(M/2) steps of Grover’s algorithm (this is like the difference speed difference between “checking if a word is palindrome” and “calculating who will win a game of chess when using a perfect strategy”). A computer that works like that… doesn’t (and probably will never) exist. But in literature they are called non-deterministic Turing machines. They would be powerful like a regular computer (not more) but unreasonably faster.



  • Ah, that’s true, I had some, but they are usually lenient on syntax. The worst offender was the OOP professor that wanted a full (kinda) Java program written on paper. During COVID he switched to allowing IDEs so it could be done online and turned in easily, and since then it’s always been an online exam








  • I would say:

    • Fedora if you like a point release, which means that every 6 months you do a big update of core stuff like the desktop environment, and on Fedora everything else is always generally up to date.
    • OpenSUSE Thumbleweed if you like a rolling release, which means that you don’t do big updates, everything is kept to the last version that the software repository has, this is how arch works except in Thumbleweed the repositories are updated slower than in arch and less likely to break.

    But you could also go for any more up to date debian-based distro, like Pop_OS or even Ubuntu, they might be easier for a newbie user. Fedora and OpenSUSE will be more up to date though.

    If you do use Ubuntu, don’t stick to just LTS versions, use the last version available (which right now happens to be an LTS version). The “extra support” it offers is not something desktop users care about, it’s outweighted by the benefits of more updated software.