NonNullSet writes "Minutemen ICBMs were deployed in the early 1960s, and grew to over 1000 in number. They were allegedly protected from a "rogue launch" by an approach known as PAL (Permissive Action Link). The PAL required that the correct 8-digit launch code be entered by the missiliers before the missile would establish ignition. What if all the PAL codes had been set to '00000000,' and 'everyone' in the Strategic Air Command knew it? That is unbelievably what happened, as described in this article from the Center for Defense Information. Not exactly a great example for getting people to choose difficult passwords!"