Failed to install Python Cryptography package with PIP and setup.py

I had a similar issue, and found I was simply missing a dependency (libssl-dev, for me). As referenced in https://cryptography.io/en/latest/installation/, ensure that all dependencies are met:

On Windows

If you’re on Windows you’ll need to make sure you have OpenSSL installed. There are pre-compiled binaries available. If your installation is in an unusual location set the LIB and INCLUDE environment variables to include thecorresponding locations. For example:

C:\> \path\to\vcvarsall.bat x86_amd64C:\> set LIB=C:\OpenSSL-1.0.1f-64bit\lib;%LIB%C:\> set INCLUDE=C:\OpenSSL-1.0.1f-64bit\include;%INCLUDE%C:\> pip install cryptography

Building cryptography on Linux

cryptography should build very easily on Linux provided you have a C compiler, headers for Python (if you’renot using pypy), and headers for the OpenSSL and libffi libraries available on your system.

For Debian and Ubuntu, the following command will ensure that the required dependencies are installed:

sudo apt-get install build-essential libssl-dev libffi-dev python-dev

For Fedora and RHEL-derivatives, the following command will ensure that the required dependencies are installed:

sudo yum install gcc libffi-devel python-devel OpenSSL-devel

You should now be able to build and install cryptography with the usual.

pip install cryptography

This is a condensed version of the information found on cryptography's installation docs page. Consult that page for the latest details.

Since this SO question keeps coming up I'll drop a response here too (I am one of the pyca/cryptography developers). Here's what you need to reliably install pyca/cryptography on the 3 major platforms.

Please note in all these cases it is highly recommended that you install into a virtualenv and not into the global package space. This is not specific to cryptography but rather is generic advice to keep your Python installation reliable. The global package space in OS provided Pythons is owned by the system and installing things via pip into it is asking for trouble.

Windows

Upgrade to the latest pip and just pip install cryptography

cryptography and cffi are both shipped as statically linked wheels.

macOS (OS X)

Upgrade to the latest pip and just pip install cryptography

cryptography and cffi are both shipped as statically linked wheels. This will work for pyenv Python, system Python, homebrew Python, etc. As long as you're on the latest pip you won't even need a compiler.

Linux

Users with the latest pip running on a glibc-based distribution (almost everything except Alpine Linux) and on x86/x86-64/aarch64 no longer need a compiler or headers because you'll get a precompiled wheel automatically. So, first thing you should try is upgrading your pip!

If you aren't manylinux compatible then here's what you need to do:

You'll need a C compiler, a Rust compiler, libffi + its development headers, and openssl + its development headers.

Debian or Ubuntu derived distributions

apt-get install build-essential libssl-dev libffi-dev python-dev followed by

pip install cryptography

Red Hat derived distributions

yum install gcc openssl-devel libffi-devel python-devel followed by

pip install cryptography

Note that as of version 3.4 cryptography now requires a Rust compiler at build time (not at runtime) so you will additionally need Rust >= 1.41.0. Check your distribution's rust or install it via rustup

For those of you running OS X, here is what worked for me:

brew install opensslenv ARCHFLAGS="-arch x86_64" LDFLAGS="-L/usr/local/opt/openssl/lib" CFLAGS="-I/usr/local/opt/openssl/include"pip install cryptography

(Running 10.9 Mavericks)

You may also want to try merging the flags and pip commands to the following per the comment below:

brew install opensslenv ARCHFLAGS="-arch x86_64" LDFLAGS="-L/usr/local/opt/openssl/lib" CFLAGS="-I/usr/local/opt/openssl/include" pip install cryptography