In our earlier days we wrote the software. We, or one or more colleagues, tested it in a variety of ways to make sure that it did what we thought it should do. As time passed the software became more complicated, and the penalties of mistakes increased, so the testing had to become more complicated. In addition, an increasing number of malevolent hackers emerged, necessitating increasingly draconian measures to key them at bay. Even then, the size and complexity of code these days make it very difficult to cover all the possibilities. Fortunately there is a government body, the US National Security Agency, that was doing its mission appropriately.