# Installation

## Using a Vendored Argon2

    $ python -Im pip install argon2-cffi

should be all it takes.

But since argon2-cffi depends on argon2-cffi-bindings that vendors Argon2’s C code by default, it can lead to complications depending on the platform.

The C code is known to compile and work on all common platforms (including x86, ARM, and PPC). On x86, an SSE2-optimized version is used.

If something goes wrong, please try to update your pip package first:

    $ python -Im pip install -U pip

Overall this should be the safest bet because argon2-cffi has been specifically tested against the vendored version.

### Wheels

Binary wheels for macOS, Windows, and Linux are provided on PyPI by argon2-cffi-bindings. With a recent-enough pip they should be used automatically.

### Source Distribution

A working C compiler and CFFI environment are required to build the argon2-cffi-bindings dependency. If you’ve been able to compile Python CFFI extensions before, argon2-cffi should install without any problems.

## Using a System-wide Installation of Argon2

If you set `ARGON2_CFFI_USE_SYSTEM` to `1` (and only `1`), argon2-cffi-bindings will not build its bindings. However binary wheels are preferred by pip and Argon2 gets installed along with argon2-cffi anyway.

Therefore you also have to instruct pip to use a source distribution of argon2-cffi-bindings:

    $ env ARGON2_CFFI_USE_SYSTEM=1 \
        python -m pip install --no-binary=argon2-cffi-bindings argon2-cffi

This approach can lead to problems around your build chain and you can run into incompatibilities between Argon2 and argon2-cffi if the latter has been tested against a different version.

It is your own responsibility to deal with these risks if you choose this path.

Added in version 18.1.0.

Changed in version 21.2.0: The `--no-binary` option value changed due to the outsourcing of the binary bindings.

## Override Automatic SSE2 Detection

Usually the build process tries to guess whether or not it should use SSE2-optimized code. Despite our best efforts, this can go wrong.

Therefore you can use the `ARGON2_CFFI_USE_SSE2` environment variable to control the process:

- If you set it to `1`, argon2-cffi will build with SSE2 support.

- If you set it to `0`, argon2-cffi will build without SSE2 support.

- If you set it to anything else, it will be ignored and argon2-cffi will try to guess.

Added in version 20.1.0.