In his early years, Stallman was a graduate student and programmer at MIT's Artificial Intelligence Labs where he would constantly engage with MIT's rich hacking culture. As an advocate for just about everything Open Source, Stallman fought back when MIT installed a password system in its Computer Science department. He would decrypt users' passwords (not an easy task given the processing power of the
1970's) and send them a message with their password in plaintext, suggesting they leave the password blank in order to re-enable anonymous use. Going into the 1980's, Stallman didn't like the proprietary stance many manufacturers were taking on their software. This eventually led Stallman to create the GNU General Public License and GNU operating system, a completely free Unix-like OS that is completely Unix-compatible.