AES 암호화 과제 참고 https://resources.saylor.org/wwwresources/archived/site/wp-content/uploads/2012/06/Advanced-Encryption-Standard.pdf https://en.wikipedia.org/wiki/Advanced_Encryption_Standard http://www.moserware.com/2009/09/stick-figure-guide-to-advanced.html https://developer-mac.tistory.com/59 https://frontjang.info/entry/AES?category=337750 https://kavaliro.com/wp-content/uploads/2014/03/AES.pdf