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The Cryspen HACL Packages

This repository contains ready-to-use crypto packages developed by Cryspen on top of HACL*. In particular, it contains a portable C crypto library that selects optimized implementations for each platform, as well as Rust, OCaml, and JavaScript bindings for this library.

Currently, we are in the process of adding more usable APIs, providing extensive documentation, and further optimizing the algorithms.

What is HACL* and why should you use HACL Packages?

HACL* is a collection of high-assurance cryptographic algorithms developed as part of Project Everest. It includes source code written in F*, generated C code, verified assembly code from the Vale project, and an agile multiplexed cryptographic provider called EverCrypt. As such, the full HACL* repository contains many software artifacts and a complicated build system that can be intimidating to a crypto developer who simply wishes to use verified crypto.


Install build dependencies

We need the following dependencies ...

Depending on your system you can install them as follows (click to expand) ...

Arch Linux
$ sudo pacman -S cmake ninja python

# Either of ...
$ sudo pacman -S clang
$ sudo pacman -S gcc
$ sudo dnf install cmake ninja-build python3

# Either of ...
$ sudo dnf install clang
$ sudo dnf install gcc
$ sudo apt install cmake ninja-build python3

# Either of ...
$ sudo apt install clang
$ sudo apt install gcc
$ brew install cmake ninja python

# Either of ...
$ brew install llvm
$ brew install gcc

Build (and test) HACL Packages

You can run ...

$ ./mach build --test

... to build HACL Packages and run the tests. All actions are driven by mach. See ./mach --help for details.

Platform support

The HACL Packages are supported based on the following tiers.

Tier 1

Tier 1 targets are guaranteed to work. These targets have automated testing to ensure that changes do not break them.

  • x86_64 Linux (x86_64-unknown-linux-gnu)
  • x86 Linux (i686-unknown-linux-gnu)
  • x86_64 macOS (x86_64-apple-darwin)
  • x86_64 Windows
    • x86_64-pc-windows-msvc
    • x86_64-pc-windows-clang
  • x86 Windows (i686-pc-windows-msvc)

Tier 2

Tier 2 targets are guaranteed to build. These targets have automated builds to ensure that changes do not break the builds. However, not all of them are always tested.

  • arm64 macOS (aarch64-apple-darwin)
  • arm64 Linux (aarch64-unknown-linux-gnu)
  • arm64 Android (aarch64-linux-android)
  • arm64 iOS (aarch64-apple-ios)
  • s390x z14 Linux (s390x-unknown-linux-gnu)

Tier 3

Tier 3 targets are supported by the code but there are no automated checks and there is no guarantee that they work.

  • ARMv7 Android (aarch64arm-linux-androideabi)
  • arm64 iOS Simulator (aarch64-apple-ios-sim)
  • x86_64 iOS (x86_64-apple-ios)
  • PowerPC
  • FreeBSD / x64

Compiler support

A modern C compiler is expected.


The following tables gives an overview over the algorithms supported by the HACL packages.

Family Algorithm Support
AEAD AES-GCM 128 AES-NI & CLMUL (x86 only)
AEAD AES-GCM 256 AES-NI & CLMUL (x86 only)
AEAD Chacha20-Poly1305 Portable | vec128 | vec256
ECDH Curve25519 Portable | BMI2 & ADX
ECDH P-256 Portable
Signature Ed25519 Portable
Signature ECDSA P-256r1 Portable
Signature ECDSA P-256k1 Portable
Signature RSA-PSS Portable
Hash SHA2-224 Portable | SHAEXT
Hash SHA2-256 Portable | SHAEXT
Hash SHA2-384 Portable
Hash SHA2-512 Portable
Hash SHA3 Portable
Hash Blake2 Portable | vec128 | vec256
Key Derivation HKDF Portable (depends on hash)
Symmetric Encryption Chacha20 Portable | vec128 | vec256
Symmetric Encryption AES 128 AES-NI & CLMUL (x86 only)
Symmetric Encryption AES 256 AES-NI & CLMUL (x86 only)
MAC HMAC Portable (depends on hash)
MAC Poly1305 Portable | vec128 | vec256 | x64 ASM


Testing is done with gtest and requires a C++11 compiler (or C++20 MSVC).

Measure Test Coverage

Test coverage in HACL Packages can be measured with ...

./mach build --tests --coverage
./mach test --coverage

Note that only clang is supported as a compiler and you may get an error ...

cc: error: unrecognized command-line option ‘-fprofile-instr-generate’; did you mean ‘-fprofile-generate’?

... when your default compiler is not clang. In this case, try to set the CC and CXX environment variables accordingly ...

export CC=clang
export CXX=clang++

Furthermore, additional tools are required to measure (and view) test coverage.

Make sure you have lcov and genhtml.

For Ubuntu these can be installed via ...

$ sudo apt install lcov

When everything went well you should be able to view the coverage reports with, e.g., ...

firefox build/Debug/coverage/full/html/index.html


Tests require the nlohmann_json package to read json test files. CMake takes care of pulling and building the package.


HACL packages are licensed under either of

at your option.