Most security flaws that I have seen seems to fall into two separate groups: trusting user input and leaking timing information. If we worked on a system to wh

Most security flaws that I have seen seems to fall into two separate groups: trusting user input and leaking timing information. If we worked on a system to whitelist proven safe input, then we would be a lot safer. What interests me is that we are essentially in an opposite of WWI: attacking is extremely easy, defense is very hard. I am not sure that this helps, but perhaps that can give some suggestions.