--- a/slides/slides01.tex	Sat Sep 30 05:28:58 2017 +0100
+++ b/slides/slides01.tex	Mon Oct 02 10:02:48 2017 +0100
@@ -935,6 +935,45 @@
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
+\frametitle{Defence in Depth}
+
+\begin{center}\small
+\pcode{urbanc:$6$3WWbKfr1$4vblknvGr6FcDeF92R5xFn3mskfdnEn...:...}
+\end{center}
+
+\begin{itemize}
+\item hashes help when password databases are leaked
+\item salts help with protecting against dictionary attacks
+  and help people who have the same password on different sites\medskip
+
+\item but they do not protect against a focused attack against a single 
+  password and also do not make poorly chosen passwords any better
+\end{itemize}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
+\frametitle{Subtle Points}
+
+\begin{itemize}
+\item in our web-application the salt needed to remain secret;
+  in password files the salt is public\bigskip
+
+\item the NYT has the ``resource'' unlocked at first
+  and locks it depending on the cookie data
+\item our ``web-application'' has the resource locked at first,
+  and unlocks it depending on the cookie data
+
+\end{itemize}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]
 \frametitle{This Course}