--- a/slides07.tex Tue Nov 13 10:46:08 2012 +0000
+++ b/slides07.tex Tue Nov 13 11:53:40 2012 +0000
@@ -828,16 +828,19 @@
\begin{frame}[c]
\frametitle{Exchange of a Fresh Key}
+\bl{$A$} and \bl{$B$} share the key \bl{$K_{AB}$} and want to share another key
+
\begin{itemize}
\item assumption \bl{$K_{AB}$} is only known to \bl{$A$} and \bl{$B$}\bigskip
\item \bl{$A \,\text{sends}\, B : A, \{N_A\}_{K_{AB}}$}
\item \bl{$B\,\text{sends}\, A : \{N_A + 1, N_B\}_{K_{AB}}$}
\item \bl{$A \,\text{sends}\, B : \{N_B + 1\}_{K_{AB}}$}
\item \bl{$B \,\text{sends}\, A : \{K^{new}_{AB}, N^{new}_B\}_{K_{AB}}$}
- \end{itemize}\bigskip\pause
+ \item<2> \bl{$A \,\text{sends}\, B : \{msg\}_{K^{new}_{AB}}$}
+ \end{itemize}\bigskip
- We hope \bl{$K^{new}_{AB}$} is only known to \bl{$A$} and \bl{$B$}.\\
- \bl{$N^{new}_B$} is to be used in future messages
+ \bl{$N^{new}_B$} is to be used in future messages\\
+ Assume \bl{$K^{new}_{AB}$} is compromised by \bl{$I$}
\end{frame}}
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@@ -846,14 +849,22 @@
\begin{frame}[c]
\frametitle{The Attack}
-An intruder \bl{$I$} convinces \bl{$B$} to accept an old compromised key
+An intruder \bl{$I$} convinces \bl{$A$} to accept the compromised key \bl{$K^{new}_{AB}$}\medskip
+\begin{minipage}{1.1\textwidth}
\begin{itemize}
\item \bl{$A \,\text{sends}\, B : A, \{N_A\}_{K_{AB}}$}
\item \bl{$B\,\text{sends}\, A : \{N_A + 1, N_B\}_{K_{AB}}$}
\item \bl{$A \,\text{sends}\, B : \{N_B + 1\}_{K_{AB}}$}
- \item \bl{$B \,\text{sends}\, A : \{K^{new}_{AB}, N^{new}_B\}_{K_{AB}}$}\pause
+ \item \bl{$B \,\text{sends}\, A : \{K^{new}_{AB}, N^{new}_B\}_{K_{AB}}$}\;\;recorded by \bl{$I$}\pause
+ \item \bl{$A \,\text{sends}\, B : A, \{M_A\}_{K_{AB}}$}
+ \item \bl{$B\,\text{sends}\, A : \{M_A + 1, M_B\}_{K_{AB}}$}
+ \item \bl{$A \,\text{sends}\, B : \{M_B + 1\}_{K_{AB}}$}
+ \item \bl{$B \,\text{sends}\, I : \{K^{anew}_{AB}, N^{anew}_B\}_{K_{AB}}$}\;intercepted by \bl{$I$}
+ \item \bl{$I \,\text{sends}\, A : \{K^{new}_{AB}, N^{new}_B\}_{K_{AB}}$}\pause
+ \item \bl{$A \,\text{sends}\, B : \{msg\}_{K^{new}_{AB}}$}
\end{itemize}
+ \end{minipage}
\end{frame}}
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