source websites:
- https://www.javacodegeeks.com/2014/07/java-keystore-tutorial.html
- http://www.fatlan.com/tag/openssl/
- https://tomcat.apache.org/tomcat-8.5-doc/ssl-howto.html
- https://docs.oracle.com/cd/E19830-01/819-4712/ablqw/index.html
- https://www.infoworld.com/article/3304289/how-to-configure-tomcat-to-always-require-https.html