&gt; In this context opposition is not necessarily conflict.<p>Than it&#x27;s not an opposition.<p>&gt; In a client-server security model the client usually wants as much as it can take and the server wants to provide as little as it has to. Are these opposed, or in conflict?<p>Now you create a malicious client which will pretent it has little, say, computational power or network capacity. So the server will have to do lots of work. Voila - a good beginning for a DoS attack. :-)<p>So, yes, these goals are in conflict and such an attack is a falsification of the soundness of your security model.