Fixing fatal error: ‘openssl/aes.h’ file not found on OS X

OS X recently started using their own library instead of OpenSSL. So new installations for anything that depends on OpenSSL might fail. If you already have OpenSSL installed on your system, for example using Homebrew, you just need to point to the library while compiling your program.

For example, if you’re trying to install the popular cryptography package from PyPI, you can do these:

The above mentioned package is a common dependency of many other packages, for example Scrapy. So if you encounter an issue like this, try installing that single dependency first and then the dependent package. In this case, first use the above command to install the cryptography package and later install Scrapy.