HTTP Public Key Pinning Extension HPKP for Apache, NGINX and Lighttpd

https://raymii.org/s/articles/HTTP_Public_Key_Pinning_Extension_HPKP.html

# Optionally load the headers module:
LoadModule headers_module modules/mod_headers.so

Header set Public-Key-Pins "pin-sha256=\"klO23nT2ehFDXCfx3eHTDRESMz3asj1muO+4aIdjiuY=\"; pin-sha256=\"633lt352PKRXbOwf4xSEa1M517scpD3l5f79xMD9r9Q=\"; max-age=2592000; includeSubDomains"