So some time ago, I made two tutorials in the Tekkit forums on the title topic. Seems like Tekkit got replaced by FTB since last time I was active and I don't see the Tekkit forums in CC anymore, so here's the links again for reference, pulled from my post history. Enjoy~
Cracking passworded doors with a disk drive:
Securer password doors:
Bonus tip: Don't use your internet passwords on your computercraft computers. When someone comes along to crack those...yeah, good luck with that.