This is was my thought too, but most keyboards have a matrix and use chips with less inputs which makes the problem harder. There are theoretical ways to write

This is was my thought too, but most keyboards have a matrix and use chips with less inputs which makes the problem harder. There are theoretical ways to write it better (you would need to have extra state for all buttons) but most firmware I have seen just samples at a rate such that the period is longer than the longest bounce.