&gt; But the difficulty of writing secure software is not about avoiding any one particular mistake; it&#x27;s the sheer number of mistakes available to be made, so that it&#x27;s easy for one mistake to slip through the cracks.<p>I&#x27;m not well versed in security, so I can&#x27;t say anything about this particular mistake; but, as a mathematics teacher, I can say that this is a fantastic description of the perils inherent in <i>any</i> creative activity, not just programming.  I hope that I have your permission to steal it for my own future use.  :-)