Pip installs pyCrypto and reports an error Could not find a version that satisfies the requirement pyCrypto (from versions: ) :
There may be a problem with the network, you can use the mirror source to speed up
Change to Douban source:
pip install pyCrypto -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com
or
pip3 install pyCrypto -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com
Successfully installed: