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+++ b/slides/bak-slides07.tex Mon Nov 10 05:57:10 2014 +0000
@@ -0,0 +1,739 @@
+\documentclass[dvipsnames,14pt,t]{beamer}
+\usepackage{proof}
+\usepackage{beamerthemeplaincu}
+%\usepackage[T1]{fontenc}
+%\usepackage[latin1]{inputenc}
+\usepackage{mathpartir}
+\usepackage{isabelle}
+\usepackage{isabellesym}
+\usepackage[absolute,overlay]{textpos}
+\usepackage{ifthen}
+\usepackage{tikz}
+\usepackage{courier}
+\usepackage{listings}
+\usetikzlibrary{arrows}
+\usetikzlibrary{positioning}
+\usetikzlibrary{calc}
+\usepackage{graphicx}
+\usetikzlibrary{shapes}
+\usetikzlibrary{shadows}
+\usetikzlibrary{plotmarks}
+
+
+\isabellestyle{rm}
+\renewcommand{\isastyle}{\rm}%
+\renewcommand{\isastyleminor}{\rm}%
+\renewcommand{\isastylescript}{\footnotesize\rm\slshape}%
+\renewcommand{\isatagproof}{}
+\renewcommand{\endisatagproof}{}
+\renewcommand{\isamarkupcmt}[1]{#1}
+\newcommand{\isaliteral}[1]{}
+\newcommand{\isactrlisub}[1]{\emph{\isascriptstyle${}\sb{#1}$}}
+
+
+% Isabelle characters
+\renewcommand{\isacharunderscore}{\_}
+\renewcommand{\isacharbar}{\isamath{\mid}}
+\renewcommand{\isasymiota}{}
+\renewcommand{\isacharbraceleft}{\{}
+\renewcommand{\isacharbraceright}{\}}
+\renewcommand{\isacharless}{$\langle$}
+\renewcommand{\isachargreater}{$\rangle$}
+\renewcommand{\isasymsharp}{\isamath{\#}}
+\renewcommand{\isasymdots}{\isamath{...}}
+\renewcommand{\isasymbullet}{\act}
+
+
+
+\definecolor{javared}{rgb}{0.6,0,0} % for strings
+\definecolor{javagreen}{rgb}{0.25,0.5,0.35} % comments
+\definecolor{javapurple}{rgb}{0.5,0,0.35} % keywords
+\definecolor{javadocblue}{rgb}{0.25,0.35,0.75} % javadoc
+
+\lstset{language=Java,
+ basicstyle=\ttfamily,
+ keywordstyle=\color{javapurple}\bfseries,
+ stringstyle=\color{javagreen},
+ commentstyle=\color{javagreen},
+ morecomment=[s][\color{javadocblue}]{/**}{*/},
+ numbers=left,
+ numberstyle=\tiny\color{black},
+ stepnumber=1,
+ numbersep=10pt,
+ tabsize=2,
+ showspaces=false,
+ showstringspaces=false}
+
+\lstdefinelanguage{scala}{
+ morekeywords={abstract,case,catch,class,def,%
+ do,else,extends,false,final,finally,%
+ for,if,implicit,import,match,mixin,%
+ new,null,object,override,package,%
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+ sensitive=true,
+ morecomment=[l]{//},
+ morecomment=[n]{/*}{*/},
+ morestring=[b]",
+ morestring=[b]',
+ morestring=[b]"""
+}
+
+\lstset{language=Scala,
+ basicstyle=\ttfamily,
+ keywordstyle=\color{javapurple}\bfseries,
+ stringstyle=\color{javagreen},
+ commentstyle=\color{javagreen},
+ morecomment=[s][\color{javadocblue}]{/**}{*/},
+ numbers=left,
+ numberstyle=\tiny\color{black},
+ stepnumber=1,
+ numbersep=10pt,
+ tabsize=2,
+ showspaces=false,
+ showstringspaces=false}
+
+% beamer stuff
+\renewcommand{\slidecaption}{APP 07, King's College London, 19 November 2013}
+\newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}% for definitions
+\newcommand{\bl}[1]{\textcolor{blue}{#1}}
+
+
+
+\begin{document}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}<1>[t]
+\frametitle{%
+ \begin{tabular}{@ {}c@ {}}
+ \\
+ \LARGE Access Control and \\[-3mm]
+ \LARGE Privacy Policies (7)\\[-6mm]
+ \end{tabular}}\bigskip\bigskip\bigskip
+
+ %\begin{center}
+ %\includegraphics[scale=1.3]{pics/barrier.jpg}
+ %\end{center}
+
+\normalsize
+ \begin{center}
+ \begin{tabular}{ll}
+ Email: & christian.urban at kcl.ac.uk\\
+ Office: & S1.27 (1st floor Strand Building)\\
+ Slides: & KEATS (also homework is there)\\
+ \end{tabular}
+ \end{center}
+
+
+\end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{}
+
+ Recall the following scenario:
+
+ \begin{itemize}
+ \item If \textcolor{blue}{Admin} says that \textcolor{blue}{\isa{file}}
+ should be deleted, then this file must be deleted.
+ \item \textcolor{blue}{Admin} trusts \textcolor{blue}{Bob} to decide whether
+ \textcolor{blue}{\isa{file}} should be deleted (delegation).
+ \item \textcolor{blue}{Bob} wants to delete \textcolor{blue}{\isa{file}}.
+ \end{itemize}\bigskip
+
+ \small
+ \textcolor{blue}{\isa{{\isaliteral{5C3C47616D6D613E}{\isasymGamma}}\ {\isaliteral{3D}{\isacharequal}}}\small\begin{tabular}{l}
+ \isa{{\isaliteral{28}{\isacharparenleft}}Admin\ says\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}},\\
+ \isa{{\isaliteral{28}{\isacharparenleft}}Admin\ says\ {\isaliteral{28}{\isacharparenleft}}{\isaliteral{28}{\isacharparenleft}}Bob\ says\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}{\isaliteral{29}{\isacharparenright}}\ {\isaliteral{5C3C52696768746172726F773E}{\isasymRightarrow}}\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}{\isaliteral{29}{\isacharparenright}}{\isaliteral{29}{\isacharparenright}}},\\
+ \isa{Bob\ says\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}}\\
+ \end{tabular}}\medskip
+
+ \textcolor{blue}{\isa{{\isaliteral{5C3C47616D6D613E}{\isasymGamma}}\ {\isaliteral{5C3C7475726E7374696C653E}{\isasymturnstile}}\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}}}
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {\hspace{-2mm}}c@ {}}The Access Control Problem\end{tabular}}
+
+
+\begin{center}
+ \begin{tikzpicture}[scale=1]
+
+ \draw[line width=1mm] (-.3, -0.5) rectangle (1.5,2);
+ \draw (-2.7,1) node {\begin{tabular}{l}access\\request\\ (\bl{$F$})\end{tabular}};
+ \draw (4.2,1) node {\begin{tabular}{l}provable/\\not provable\end{tabular}};
+ \draw (0.6,0.8) node {\footnotesize \begin{tabular}{l}AC-\\ Checker:\\ applies\\ inference\\ rules\end{tabular}};
+
+ \draw[red, ->, line width = 2mm] (1.7,1) -- (2.7,1);
+ \draw[red,<-, line width = 2mm] (-0.6,1) -- (-1.6,1);
+ \draw[red, <-, line width = 3mm] (0.6,2.2) -- (0.6,3.2);
+
+ \draw (0.6,4) node {\begin{tabular}{l}\large Access Policy (\boldmath\bl{$\Gamma$})\end{tabular}};
+
+ \end{tikzpicture}
+\end{center}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+
+\begin{itemize}
+\item \bl{$P \,\text{says}\, F$} means \bl{$P$} can send a ``signal'' \bl{$F$} through a wire, or
+can make a ``statement'' \bl{$F$}\bigskip\pause
+
+\item \bl{$P$} is entitled to do \bl{$F$}\smallskip\\
+\bl{$P \,\text{controls}\, F \,\dn\, (P\,\text{says}\, F) \Rightarrow F$}\medskip
+
+\begin{center}
+\bl{\infer{\Gamma \vdash F}{\Gamma \vdash P\,\text{controls}\, F & \Gamma \vdash P\,\text{says}\,F}}
+\end{center}
+
+
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Security Levels}
+ \small
+
+ \begin{itemize}
+ \item Top secret (\bl{$T\!S$})
+ \item Secret (\bl{$S$})
+ \item Public (\bl{$P$})
+ \end{itemize}
+
+ \begin{center}
+ \bl{$slev(P) < slev(S) < slev(T\!S)$}\pause
+ \end{center}
+
+ \begin{itemize}
+ \item Bob has a clearance for ``secret''
+ \item Bob can read documents that are public or sectret, but not top secret
+ \end{itemize}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Reading a File}
+
+ \bl{\begin{center}
+ \begin{tabular}{c}
+ \begin{tabular}{@ {}l@ {}}
+ \only<2->{\textcolor{red}{$slev($File$)$ $<$ $slev($Bob$)$ $\Rightarrow$}}\\
+ \only<2->{\hspace{3cm}}Bob controls Permitted $($File, read$)$\\
+ Bob says Permitted $($File, read$)$\only<2->{\\}
+ \only<2>{\textcolor{red}{$slev($File$)$ $<$ $slev($Bob$)$}}%
+ \only<3>{\textcolor{red}{$slev($File$)$ $=$ $P$}\\}%
+ \only<3>{\textcolor{red}{$slev($Bob$)$ $=$ $S$}\\}%
+ \only<3>{\textcolor{red}{$slev(P)$ $<$ $slev(S)$}\\}%
+ \end{tabular}\\
+ \hline
+ Permitted $($File, read$)$
+ \end{tabular}
+ \end{center}}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Substitution Rule}
+ \small
+
+ \bl{\begin{center}
+ \begin{tabular}{c}
+ $\Gamma \vdash slev(P) = l_1$ \hspace{4mm} $\Gamma \vdash slev(Q) = l_2$
+ \hspace{4mm} $\Gamma \vdash l_1 < l_2$\\\hline
+ $\Gamma \vdash slev(P) < slev(Q)$
+ \end{tabular}
+ \end{center}}\bigskip\pause
+
+ \begin{itemize}
+ \item \bl{$slev($Bob$)$ $=$ $S$}
+ \item \bl{$slev($File$)$ $=$ $P$}
+ \item \bl{$slev(P) < slev(S)$}
+ \end{itemize}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Reading a File}
+
+ \bl{\begin{center}
+ \begin{tabular}{c}
+ \begin{tabular}{@ {}l@ {}}
+ $slev($File$)$ $<$ $slev($Bob$)$ $\Rightarrow$\\
+ \hspace{3cm}Bob controls Permitted $($File, read$)$\\
+ Bob says Permitted $($File, read$)$\\
+ $slev($File$)$ $=$ $P$\\
+ $slev($Bob$)$ $=$ $T\!S$\\
+ \only<1>{\textcolor{red}{$?$}}%
+ \only<2>{\textcolor{red}{$slev(P) < slev(S)$}\\}%
+ \only<2>{\textcolor{red}{$slev(S) < slev(T\!S)$}}%
+ \end{tabular}\\
+ \hline
+ Permitted $($File, read$)$
+ \end{tabular}
+ \end{center}}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Transitivity Rule}
+ \small
+
+ \bl{\begin{center}
+ \begin{tabular}{c}
+ $\Gamma \vdash l_1 < l_2$
+ \hspace{4mm} $\Gamma \vdash l_2 < l_3$\\\hline
+ $\Gamma \vdash l_1 < l_3$
+ \end{tabular}
+ \end{center}}\bigskip
+
+ \begin{itemize}
+ \item \bl{$slev(P) < slev (S)$}
+ \item \bl{$slev(S) < slev (T\!S)$}
+ \item[] \bl{$slev(P) < slev (T\!S)$}
+ \end{itemize}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Reading Files}
+
+ \begin{itemize}
+ \item Access policy for Bob for reading
+ \end{itemize}
+
+ \bl{\begin{center}
+ \begin{tabular}{c}
+ \begin{tabular}{@ {}l@ {}}
+ $\forall f.\;slev(f)$ \only<1>{$<$}\only<2>{\textcolor{red}{$\le$}} $slev($Bob$)$ $\Rightarrow$\\
+ \hspace{3cm}Bob controls Permitted $(f$, read$)$\\
+ Bob says Permitted $($File, read$)$\\
+ $slev($File$)$ $=$ \only<1>{$P$}\only<2>{\textcolor{red}{$T\!S$}}\\
+ $slev($Bob$)$ $=$ $T\!S$\\
+ $slev(P) < slev(S)$\\
+ $slev(S) < slev(T\!S)$
+ \end{tabular}\\
+ \hline
+ Permitted $($File, read$)$
+ \end{tabular}
+ \end{center}}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Writing Files}
+
+ \begin{itemize}
+ \item Access policy for Bob for {\bf writing}
+ \end{itemize}
+
+ \bl{\begin{center}
+ \begin{tabular}{c}
+ \begin{tabular}{@ {}l@ {}}
+ $\forall f.\;slev($Bob$)$ $\le$ $slev(f)$ $\Rightarrow$\\
+ \hspace{3cm}Bob controls Permitted $(f$, write$)$\\
+ Bob says Permitted $($File, write$)$\\
+ $slev($File$)$ $=$ $T\!S$\\
+ $slev($Bob$)$ $=$ $S$\\
+ $slev(P) < slev(S)$\\
+ $slev(S) < slev(T\!S)$
+ \end{tabular}\\
+ \hline
+ Permitted $($File, write$)$
+ \end{tabular}
+ \end{center}}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Encrypted Messages}
+
+ \begin{itemize}
+ \item Alice sends a message \bl{$m$}
+ \begin{center}
+ \bl{Alice says $m$}
+ \end{center}\medskip\pause
+
+ \item Alice sends an encrypted message \bl{$m$}\\ (with key \bl{$K$})
+ \begin{center}
+ \bl{Alice says $\{m\}_K$}
+ \end{center}\medskip\pause
+
+ \item Decryption of Alice's message\smallskip
+ \begin{center}
+ \bl{\mbox{\infer{\Gamma \vdash \text{Alice}\;\text{says}\;m}
+ {\Gamma \vdash \text{Alice}\;\text{says}\;\{m\}_K & \Gamma \vdash \text{Alice}\,\text{says}\,K}}}
+ \end{center}
+ \end{itemize}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Encryption}
+
+ \begin{itemize}
+ \item Encryption of a message\smallskip
+ \begin{center}
+ \bl{\mbox{\infer{\Gamma \vdash \text{Alice}\;\text{says}\;\{m\}_K}
+ {\Gamma \vdash \text{Alice}\;\text{says}\;m & \Gamma \vdash \text{Alice}\,\text{says}\,K}}}
+ \end{center}
+ \end{itemize}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{Trusted Third Party}
+
+Simple protocol for establishing a secure connection via a mutually
+trusted 3rd party (server):
+
+\begin{center}
+\begin{tabular}{@ {\hspace{-7mm}}l@{\hspace{2mm}}r@ {\hspace{1mm}}l}
+Message 1 & \bl{$A \rightarrow S :$} & \bl{$A, B$}\\
+Message 2 & \bl{$S \rightarrow A :$} & \bl{$\{K_{AB}\}_{K_{AS}}$} and \bl{$\{\{K_{AB}\}_{K_{BS}} \}_{K_{AS}}$}\\
+Message 3 & \bl{$A \rightarrow B :$} & \bl{$\{K_{AB}\}_{K_{BS}} $}\\
+Message 4 & \bl{$A \rightarrow B :$} & \bl{$\{m\}_{K_{AB}}$}\\
+\end{tabular}
+\end{center}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Sending Rule}
+
+ \bl{\begin{center}
+ \mbox{$\infer{\Gamma \vdash Q \;\text{says}\; F}
+ {\Gamma \vdash P \;\text{says}\; F & \Gamma \vdash P \;\text{sends}\; Q : F}$}
+ \end{center}}\bigskip\pause
+
+ \bl{$P \,\text{sends}\, Q : F \dn$}\\
+ \hspace{6mm}\bl{$(P \,\text{says}\, F) \Rightarrow (Q \,\text{says}\, F)$}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Trusted Third Party}
+
+ \begin{center}
+ \bl{\begin{tabular}{l}
+ $A$ sends $S$ : $\text{Connect}(A,B)$\\
+ \bl{$S \,\text{says}\, (\text{Connect}(A,B) \Rightarrow$}\\
+ \hspace{2.5cm}\bl{$\{K_{AB}\}_{K_{AS}} \wedge
+ \{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}})$}\\
+ $S$ sends $A$ : $\{K_{AB}\}_{K_{AS}}$ \bl{$\wedge$} $\{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}}$\\
+ $A$ sends $B$ : $\{K_{AB}\}_{K_{BS}}$\\
+ $A$ sends $B$ : $\{m\}_{K_{AB}}$
+ \end{tabular}}
+ \end{center}\bigskip\pause
+
+
+ \bl{$\Gamma \vdash B \,\text{says} \, m$}?
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Public/Private Keys}
+
+ \begin{itemize}
+ \item Bob has a private and public key: \bl{$K_{Bob}^{pub}$}, \bl{$K_{Bob}^{priv}$}\bigskip
+ \begin{center}
+ \bl{\mbox{\infer{\Gamma \vdash \text{Alice}\;\text{says}\;m}
+ {\Gamma \vdash \text{Alice}\;\text{says}\;\{m\}_{K_{Bob}^{pub}} &
+ \Gamma \vdash K_{Bob}^{priv}}}}
+ \end{center}\bigskip\pause
+
+ \item this is {\bf not} a derived rule!
+ \end{itemize}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+% \begin{itemize}
+% \item Alice calls Sam for a key to communicate with Bob
+% \item Sam responds with a key that Alice can read and a key Bob can read (pre-shared)
+ % \item Alice sends the message encrypted with the key and the second key it recieved
+ % \end{itemize}\bigskip
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Sending Rule}
+
+
+ \bl{\begin{center}
+ \mbox{\infer{\Gamma \vdash Q \;\textit{says}\; F}
+ {\Gamma \vdash P \;\textit{says}\; F & \Gamma \vdash P \;\textit{sends}\; Q : F}}
+ \end{center}}\bigskip\pause
+
+ \bl{$P \,\text{sends}\, Q : F \dn$}\\
+ \hspace{6mm}\bl{$(P \,\text{says}\, F) \Rightarrow (Q \,\text{says}\, F)$}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Trusted Third Party}
+
+ \begin{center}
+ \bl{\begin{tabular}{l}
+ $A$ sends $S$ : $\textit{Connect}(A,B)$\\
+ \bl{$S \,\text{says}\, (\textit{Connect}(A,B) \Rightarrow$}\\
+ \hspace{2.5cm}\bl{$\{K_{AB}\}_{K_{AS}} \wedge
+ \{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}})$}\\
+ $S$ sends $A$ : $\{K_{AB}\}_{K_{AS}}$ \bl{$\wedge$} $\{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}}$\\
+ $A$ sends $B$ : $\{K_{AB}\}_{K_{BS}}$\\
+ $A$ sends $B$ : $\{m\}_{K_{AB}}$
+ \end{tabular}}
+ \end{center}\bigskip\pause
+
+
+ \bl{$\Gamma \vdash B \,\text{says} \, m$}?
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Challenge-Response Protocol}
+
+ \begin{itemize}
+ \item an engine \bl{$E$} and a transponder \bl{$T$} share a key \bl{$K$}\bigskip
+ \item \bl{$E$} sends out a \alert{nonce} \bl{$N$} (random number) to \bl{$T$}\bigskip
+ \item \bl{$T$} responds with \bl{$\{N\}_K$}\bigskip
+ \item if \bl{$E$} receives \bl{$\{N\}_K$} from \bl{$T$}, it starts engine
+ \end{itemize}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Challenge-Response Protocol}
+
+ \begin{center}
+ \bl{\begin{tabular}{l}
+ $E \;\text{says}\; N$\hfill(start)\\
+ $E \;\text{sends}\; T : N$\hfill(challenge)\\
+ $(T \;\text{says}\; N) \Rightarrow (T \;\text{sends}\; E : \{N\}_K \wedge$\\
+ \hspace{3.5cm} $T \;\text{sends}\; E : \text{Id}(T))$\;\;\;\hfill(response)\\
+ $T \;\text{says}\; K$\hfill(key)\\
+ $T \;\text{says}\; \text{Id}(T)$\hfill(identity)\\
+ $(E \;\text{says}\; \{N\}_K \wedge E \;\text{says}\; \text{Id}(T)) \Rightarrow$\\
+ \hspace{5cm}$ \text{start\_engine}(T)$\hfill(engine)\\
+ \end{tabular}}
+ \end{center}\bigskip
+
+ \bl{$\Gamma \vdash \text{start\_engine}(T)$}?
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{Exchange of a Fresh Key}
+
+\bl{$A$} and \bl{$B$} share a (``super-secret'') key \bl{$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}}$}
+ \item<2> \bl{$A \,\text{sends}\, B : \{msg\}_{K^{new}_{AB}}$}
+ \end{itemize}\bigskip
+
+ Assume \bl{$K^{new}_{AB}$} is compromised by \bl{$I$}
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+ \mode<presentation>{
+ \begin{frame}[c]
+ \frametitle{The Attack}
+
+An intruder \bl{$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}}$}\;\;recorded by \bl{$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^{newer}_{AB}, N^{newer}_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}}$}\;\;\;\;\bl{$I$} can read it also
+ \end{itemize}
+ \end{minipage}
+
+ \end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+
+A Man-in-the-middle attack in real life:
+
+\begin{itemize}
+\item the card only says yes or no to the terminal if the PIN is correct
+\item trick the card in thinking transaction is verified by signature
+\item trick the terminal in thinking the transaction was verified by PIN
+\end{itemize}
+
+\begin{minipage}{1.1\textwidth}
+\begin{center}
+\mbox{}\hspace{-6mm}\includegraphics[scale=0.5]{pics/chip-attack.png}
+\includegraphics[scale=0.3]{pics/chipnpinflaw.png}
+\end{center}
+\end{minipage}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{Problems with EMV}
+
+\begin{itemize}
+\item it is a wrapper for many protocols
+\item specification by consensus (resulted unmanageable complexity)
+\item its specification is 700 pages in English plus 2000+ pages for testing, additionally some
+further parts are secret
+\item other attacks have been found
+
+\item one solution might be to require always online verification of the PIN with the bank
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{c}Problems with WEP (Wifi)\end{tabular}}
+
+\begin{itemize}
+\item a standard ratified in 1999
+\item the protocol was designed by a committee not including cryptographers
+\item it used the RC4 encryption algorithm which is a stream cipher requiring a unique nonce
+\item WEP did not allocate enough bits for the nonce
+\item for authenticating packets it used CRC checksum which can be easily broken
+\item the network password was used to directly encrypt packages (instead of a key negotiation protocol)\bigskip
+\item encryption was turned off by default
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{Protocols are Difficult}
+
+\begin{itemize}
+\item even the systems designed by experts regularly fail\medskip
+\item try to make everything explicit (you need to authenticate all data you might rely on)\medskip
+\item the one who can fix a system should also be liable for the losses\medskip
+\item cryptography is often not {\bf the} answer\bigskip\bigskip
+\end{itemize}
+
+logic is one way protocols are studied in academia
+(you can use computers to search for attacks)
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{Public-Key Infrastructure}
+
+\begin{itemize}
+\item the idea is to have a certificate authority (CA)
+\item you go to the CA to identify yourself
+\item CA: ``I, the CA, have verified that public key \bl{$P^{pub}_{Bob}$} belongs to Bob''\bigskip
+\item CA must be trusted by everybody
+\item What happens if CA issues a false certificate? Who pays in case of loss? (VeriSign
+explicitly limits liability to \$100.)
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+
+
+
+
+
+\end{document}
+
+%%% Local Variables:
+%%% mode: latex
+%%% TeX-master: t
+%%% End:
+