pip安装
sudo apt-get install python3-pip
python3(python2安装 将python3-dev 改成python-dev)
sudo apt-get install build-essential libssl-dev libffi-dev python3-dev
sudo pip install --upgrade setuptools
pip3 install cryptography -i https://pypi.douban.com/simple
参考
https://cryptography.io/en/latest/installation/#debian-ubuntu