dafny VS evercrypt-rust

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 don't think something that specific exists. There are a very large number of formal methods tools, each with different specialties / domains.

For verification with proof assistants, [Software Foundations](https://softwarefoundations.cis.upenn.edu/) and [Concrete Semantics](http://concrete-semantics.org/) are both solid.

For verification via model checking, you can check out [Learn TLA+](https://learntla.com/), and the more theoretical [Specifying Systems](https://lamport.azurewebsites.net/tla/book-02-08-08.pdf).

For more theory, check out [Formal Reasoning About Programs](http://adam.chlipala.net/frap/).

And for general projects look at [F*](https://www.fstar-lang.org/) and [Dafny](https://dafny.org/).

Dafny and Whiley are two examples with explicit verification support. Idris and other dependently typed languages should all be rich enough to express the required predicate but might not necessarily be able to accept a reasonable implementation as proof. Isabelle, Lean, Coq, and other theorem provers definitely can express the capability but aren't going to churn out much in the way of executable programs; they're more useful to guide an implementation in a more practical functional language but then the proof is separated from the implementation, and you could also use tools like TLA+.

https://dafny.org/

https://whiley.org/

https://www.idris-lang.org/

https://isabelle.in.tum.de/

https://leanprover.github.io/

https://coq.inria.fr/

http://lamport.azurewebsites.net/tla/tla.html

> I think we can assume it won't be as efficient has hand written code

Actually, surprisingly, not necessarily the case!

If you'll refer to the discussion in https://github.com/dafny-lang/dafny/issues/601 and in https://github.com/dafny-lang/dafny/issues/547, Dafny can statically prove that certain compiler branches are not possible and will never be taken (such as out-of-bounds on index access, logical assumptions about whether a value is greater than or less than some other value, etc). This lets you code in the assumptions (__assume in C++ or unreachable_unchecked() under rust) that will allow the compiler to optimize the codegen using this information.

Most of the proof assistants out there: Lean, Coq, Dafny, Isabelle, F*, Idris 2, and Agda. And the main concepts are dependent types, Homotopy Type Theory AKA HoTT, and Category Theory. Warning: HoTT and Category Theory are really dense, you're going to really need to research them.

CompCert is also very impressive. It's not, however, free software / open source (the source is available though)

https://www.absint.com/compcert/structure.htm

A problem with both seL4 and CompCert is that the code written to express the proofs is huge, much larger than code that actually does stuff. This puts a ceiling on the size of the projects we can verify.

F* is a language that tries to address that, by finding proofs with z3, a smt prover; z3 can't prove everything on its own but it cuts down proof code by orders of magnitude. They have written a verified cryptography stack and TLS stack, and want to write a whole verified http stack.

https://www.fstar-lang.org/

https://github.com/project-everest/hacl-star

https://www.mitls.org/

https://project-everest.github.io/

F* (through Low, a verified low-level subset of F) can extract verified code to C, which is kind of the inverse than the seL4 proof: seL4 begins with C code and enriches it with proofs of correctness; hacl* (a verified crypto F* lib) begins with a proven correct F* code and extracts C code (I gather the actual crypto primitives is compiled directly to asm code because C has some problems with constant time stuff). This enables hacl* to make bindings to other languages that can just call C code, like this Rust binding

https://github.com/franziskuskiefer/evercrypt-rust

Also this F* stuff is all free software / open source, so it might become a very prevalent crypto and TLS stack

evercrypt-rust (verified) Rust bindings for evercrypt, a set of high-performance HACL*-verified implementations of cryptographic primitives. bindings crate, bringing HACL-verified cryptographic primitives.