Installation

You can install cryptography with pip:

$ pip install cryptography

Supported platforms

Currently we test cryptography on Python 2.7, 3.4, 3.5, 3.6, and PyPy 5.3+ on these operating systems.

  • x86-64 CentOS 7.x
  • x86-64 FreeBSD 11
  • macOS 10.12 Sierra, 10.11 El Capitan
  • x86-64 Ubuntu 14.04, 16.04, and rolling
  • x86-64 Debian Wheezy (7.x), Jessie (8.x), Stretch (9.x), and Sid (unstable)
  • x86-64 Alpine (latest)
  • 32-bit and 64-bit Python on 64-bit Windows Server 2012

We test compiling with clang as well as gcc and use the following OpenSSL releases:

  • OpenSSL 1.0.1
  • OpenSSL 1.0.1e-fips (RHEL/CentOS 7)
  • OpenSSL 1.0.1f
  • OpenSSL 1.0.1j-freebsd
  • OpenSSL 1.0.2-latest
  • OpenSSL 1.1.0-latest

Building cryptography on Windows

The wheel package on Windows is a statically linked build (as of 0.5) so all dependencies are included. To install cryptography, you will typically just run

$ pip install cryptography

If you prefer to compile it yourself you’ll need to have OpenSSL installed. You can compile OpenSSL yourself as well or use the binaries we build for our release infrastructure (openssl-release). Be sure to download the proper version for your architecture and Python (2010 works for Python 2.7, 3.3, and 3.4 while 2015 is required for 3.5 and above). Wherever you place your copy of OpenSSL you’ll need to set the LIB and INCLUDE environment variables to include the proper locations. For example:

C:\> \path\to\vcvarsall.bat x86_amd64
C:\> set LIB=C:\OpenSSL-win64\lib;%LIB%
C:\> set INCLUDE=C:\OpenSSL-win64\include;%INCLUDE%
C:\> pip install cryptography

As of OpenSSL 1.1.0 the library names have changed from libeay32 and ssleay32 to libcrypto and libssl (matching their names on all other platforms). cryptography links against the new 1.1.0 names by default. If you need to compile cryptography against an older version then you must set CRYPTOGRAPHY_WINDOWS_LINK_LEGACY_OPENSSL or else installation will fail.

If you need to rebuild cryptography for any reason be sure to clear the local wheel cache.

Building cryptography on Linux

cryptography ships a manylinux1 wheel (as of 2.0) so all dependencies are included. For users on pip 8.1 or above running on a manylinux1 compatible distribution (almost everything except Alpine) all you should need to do is:

$ pip install cryptography

If you are on Alpine or just want to compile it yourself then cryptography requires a compiler, headers for Python (if you’re not using pypy), and headers for the OpenSSL and libffi libraries available on your system.

Alpine

Replace python3-dev with python-dev if you’re using Python 2.

$ sudo apk add gcc musl-dev python3-dev libffi-dev openssl-dev

If you get an error with openssl-dev you may have to use libressl-dev.

Debian/Ubuntu

Replace python3-dev with python-dev if you’re using Python 2.

$ sudo apt-get install build-essential libssl-dev libffi-dev python3-dev

RHEL/CentOS

$ sudo yum install redhat-rpm-config gcc libffi-devel python-devel \
    openssl-devel

Building

You should now be able to build and install cryptography. To avoid getting the pre-built wheel on manylinux1 distributions you’ll need to use --no-binary.

$ pip install cryptography --no-binary cryptography

Using your own OpenSSL on Linux

Python links to OpenSSL for its own purposes and this can sometimes cause problems when you wish to use a different version of OpenSSL with cryptography. If you want to use cryptography with your own build of OpenSSL you will need to make sure that the build is configured correctly so that your version of OpenSSL doesn’t conflict with Python’s.

The options you need to add allow the linker to identify every symbol correctly even when multiple versions of the library are linked into the same program. If you are using your distribution’s source packages these will probably be patched in for you already, otherwise you’ll need to use options something like this when configuring OpenSSL:

$ ./config -Wl,--version-script=openssl.ld -Wl,-Bsymbolic-functions -fPIC shared

You’ll also need to generate your own openssl.ld file. For example:

OPENSSL_1.1.0E_CUSTOM {
    global:
        *;
};

You should replace the version string on the first line as appropriate for your build.

Static Wheels

Cryptography ships statically-linked wheels for macOS, Windows, and Linux (via manylinux1). This allows compatible environments to use the most recent OpenSSL, regardless of what is shipped by default on those platforms. Some Linux distributions (most notably Alpine) are not manylinux1 compatible so we cannot distribute wheels for them.

However, you can build your own statically-linked wheels that will work on your own systems. This will allow you to continue to use relatively old Linux distributions (such as LTS releases), while making sure you have the most recent OpenSSL available to your Python programs.

To do so, you should find yourself a machine that is as similar as possible to your target environment (e.g. your production environment): for example, spin up a new cloud server running your target Linux distribution. On this machine, install the Cryptography dependencies as mentioned in Building cryptography on Linux. Please also make sure you have virtualenv installed: this should be available from your system package manager.

Then, paste the following into a shell script. You’ll need to populate the OPENSSL_VERSION variable. To do that, visit openssl.org and find the latest non-FIPS release version number, then set the string appropriately. For example, for OpenSSL 1.0.2k, use OPENSSL_VERSION="1.0.2k".

When this shell script is complete, you’ll find a collection of wheel files in a directory called wheelhouse. These wheels can be installed by a sufficiently-recent version of pip. The Cryptography wheel in this directory contains a statically-linked OpenSSL binding, which ensures that you have access to the most-recent OpenSSL releases without corrupting your system dependencies.

set -e

OPENSSL_VERSION="VERSIONGOESHERE"
CWD=$(pwd)

virtualenv env
. env/bin/activate
pip install -U setuptools
pip install -U wheel pip
curl -O https://www.openssl.org/source/openssl-${OPENSSL_VERSION}.tar.gz
tar xvf openssl-${OPENSSL_VERSION}.tar.gz
cd openssl-${OPENSSL_VERSION}
./config no-shared no-ssl2 no-ssl3 -fPIC --prefix=${CWD}/openssl
make && make install
cd ..
CFLAGS="-I${CWD}/openssl/include" LDFLAGS="-L${CWD}/openssl/lib" pip wheel --no-use-wheel cryptography

Building cryptography on macOS

Note

If installation gives a fatal error: 'openssl/aes.h' file not found see the FAQ for information about how to fix this issue.

The wheel package on macOS is a statically linked build (as of 1.0.1) so for users with pip 8 or above you only need one step:

$ pip install cryptography

If you want to build cryptography yourself or are on an older macOS version, cryptography requires the presence of a C compiler, development headers, and the proper libraries. On macOS much of this is provided by Apple’s Xcode development tools. To install the Xcode command line tools (on macOS 10.9+) open a terminal window and run:

$ xcode-select --install

This will install a compiler (clang) along with (most of) the required development headers.

You’ll also need OpenSSL, which you can obtain from Homebrew or MacPorts. Cryptography does not support Apple’s deprecated OpenSSL distribution.

To build cryptography and dynamically link it:

Homebrew

$ brew install openssl@1.1
$ env LDFLAGS="-L$(brew --prefix openssl@1.1)/lib" CFLAGS="-I$(brew --prefix openssl@1.1)/include" pip install cryptography

MacPorts:

$ sudo port install openssl
$ env LDFLAGS="-L/opt/local/lib" CFLAGS="-I/opt/local/include" pip install cryptography

You can also build cryptography statically:

Homebrew

$ brew install openssl@1.1
$ env CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1 LDFLAGS="$(brew --prefix openssl@1.1)/lib/libssl.a $(brew --prefix openssl@1.1)/lib/libcrypto.a" CFLAGS="-I$(brew --prefix openssl@1.1)/include" pip install cryptography

MacPorts:

$ sudo port install openssl
$ env CRYPTOGRAPHY_SUPPRESS_LINK_FLAGS=1 LDFLAGS="/opt/local/lib/libssl.a /opt/local/lib/libcrypto.a" CFLAGS="-I/opt/local/include" pip install cryptography

If you need to rebuild cryptography for any reason be sure to clear the local wheel cache.

Building cryptography with conda

Because of a bug in conda, attempting to install cryptography out of the box will result in an error. This can be resolved by setting the library path environment variable for your platform.

On macOS:

$ env DYLD_LIBRARY_PATH="$HOME/anaconda/lib" pip install cryptography

and on Linux:

$ env LD_LIBRARY_PATH="$HOME/anaconda/lib" pip install cryptography

You will need to set this variable every time you start Python. For more information, consult Greg Wilson’s blog post on the subject.