picoCTF VS z3

PicoCTF - The platform used to run picoCTF. A great framework to host any CTF.

Code correctness is a lost art. I requirement to think in abstractions is what scares a lot of devs to avoid it. The higher abstraction language (formal specs) focus on a dedicated language to describe code, whereas lower abstractions (code contracts) basically replace validation logic with a better model.

C# once had Code Contracts[1]; a simple yet powerful way to make formal specifications. The contracts was checked at compile time using the Z3 SMT solver[2]. It was unfortunately deprecated after a few years[3] and once removed from the .NET Runtime it was declared dead.

The closest thing C# now have is probably Dafny[4] while the C# dev guys still try to figure out how to implement it directly in the language[5].

[1] https://www.microsoft.com/en-us/research/project/code-contra...

[2] https://github.com/Z3Prover/z3

[3] https://github.com/microsoft/CodeContracts

[4] https://github.com/dafny-lang/dafny

[5] https://github.com/dotnet/csharplang/issues/105

I believe, Nim also has this functionality, although, it uses the [0]Z3Prover tool with a nim frontend [1]"DrNim" for proving.

[0]https://github.com/Z3Prover/z3

Don't get me wrong, there are times when Microsoft got it right the first time that was technically far superior to their competitors. Windows IOCP was theoretically capable of doing C10K as far back in 1994-95 when there wasn't any hardware support yet and UNIX world was bickering over how to do asynchronous I/O. Years later POSIX came up with select which was a shoddy little shit in comparison. Linux caved in finally only as recently as 2019 and implemented io_uring. Microsoft research has contributed some very interesting things to computer science like Z3 SAT solver and in collaboration with INRIA made languages like F* and Low* for formal specification and verification. But all this dwarfs in comparison to all the harm they did.

Other than that, you should look at Z3 which is pretty damn good at these sort of theorems/constraints.

In the end I used Z3 Julia bindings instead. The hardest part was to get the result back from it, because I kept running into assertion violations from inside Z3

> And you propose me instead to go and reverse engineer library Js code which I am not that proficient in, and rewrite all code in Java instead?..

Yes, rather than demand others cater to your whims, frankly.

Do you realise how hypocritical it sounds to complain that you are not proficient in Javascript, when others might not be proficient in ?

Go use Z3 if you need a prover in C++ (or Java), its far more robust (provided its the type you're after) than someones 700 LoC JavaScript implementation.

https://github.com/Z3Prover/z3

My open-source project https://github.com/obijywk/grilops (excuse the shameless plug) can help when creating Nikoli-style grid logic puzzles, and we used it during the development of Ents, Resolution, and Missing Pieces (and to check uniqueness of Digital Gaming solutions). The constraint solver library it depends on, https://github.com/Z3Prover/z3 from Microsoft Research, is also very useful on its own, and we used it to help with the creation of Art Gallery and Global Shipping Crisis. Dennis Yurichev's SAT/SMT By Example is an extensive resource for learning how to use these kinds of tools to solve all sorts of problems, including puzzle solving.