The simple `pip install cryptography` command does not work on OS X (only tested on El Capitan). What I tried: ``` brew install openssl pip install cryptography ``` results in ``` build/temp.macosx-10.9-intel-2.7/_openssl.c:425:10: fatal error: 'openssl/aes.h' file not found #include <openssl/aes.h> ^ 1 error generated. error: command 'clang' failed with exit status 1 ``` The following workaround helped: ``` $ ARCHFLAGS="-arch x86_64" LDFLAGS="-L/usr/local/opt/openssl/lib" \ CFLAGS="-I/usr/local/opt/openssl/include" pip install cryptography ```