KreMLin is a tool that extracts an F* program to readable C code. If the F* program verifies against a low-level memory model that talks about the stack and the heap; if it is first-order; if it obeys certain restrictions (e.g. non-recursive data types) then KreMLin will turn it into C.
- DESIGN.md has a technical overview of the different transformation passes performed by KreMLin
- MANUAL.md contains some tips&tricks when working with KreMLin.
This work has been formalized on paper. We state that the compilation of such F* programs to C preserves semantics. We start from Low*, a subset of F*, and relate its semantics to CompCert's Clight.
- the ICFP 2017 Paper provides an overview of KreMLin as well as a paper formalization of our compilation toolchain
We have written 20,000 lines of low-level F* code, implementing the TLS 1.3 record layer. As such, KreMLin is a key component of Project Everest.
- HACL*, our High Assurance Crypto Library, provides numerous cryptographic primitives written in F*; these primitives enjoy memory safety, functional correctness, and some degree of side-channel resistance -- they extract to C via KreMLin.
Make sure you run opam update first, so that by running the opam install
command below you get process-0.2.1 (process version 0.2 doesn't work on
Windows). Install all of the packages below, on Windows possibly following
instructions from https://github.com/protz/ocaml-installer/wiki for "difficult"
packages (e.g. ppx_deriving).
$ opam install ppx_deriving_yojson zarith pprint menhir ulex process fix wasm
To build just run make from this directory.
Note: KreMLin's master branch runs against F*'s stable branch, and
KreMLin's fstar-master branch runs against F*'s master branch.
Note: on OSX, KreMLin is happier if you have greadlink installed (brew install coreutils).
If you have the right version of F* and fstar.exe is in your PATH then you
can run the KreMLin test suite by doing make test.
File a bug if things don't work!
The simple example from the ML Workshop Paper is available in
test/ML16.fst and you can compile it with make ML16.exe.
Also check out the --help flag:
$ ./krml --help
Kremlin is released under the Apache 2.0 license; see LICENSE for more details.