--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/slides/slides04.tex Sun Sep 22 15:22:11 2013 +0100
@@ -0,0 +1,1014 @@
+\documentclass[dvipsnames,14pt,t]{beamer}
+\usepackage{beamerthemeplainculight}
+\usepackage[T1]{fontenc}
+\usepackage[latin1]{inputenc}
+\usepackage{mathpartir}
+\usepackage[absolute,overlay]{textpos}
+\usepackage{ifthen}
+\usepackage{tikz}
+\usepackage{pgf}
+\usepackage{calc}
+\usepackage{ulem}
+\usepackage{courier}
+\usepackage{listings}
+\renewcommand{\uline}[1]{#1}
+\usetikzlibrary{arrows}
+\usetikzlibrary{automata}
+\usetikzlibrary{shapes}
+\usetikzlibrary{shadows}
+\usetikzlibrary{positioning}
+\usetikzlibrary{calc}
+\usepackage{graphicx}
+
+\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,%
+ private,protected,requires,return,sealed,%
+ super,this,throw,trait,true,try,%
+ type,val,var,while,with,yield},
+ otherkeywords={=>,<-,<\%,<:,>:,\#,@},
+ 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 04, King's College London, 16 October 2012}
+
+
+\begin{document}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}<1>[t]
+\frametitle{%
+ \begin{tabular}{@ {}c@ {}}
+ \\
+ \LARGE Access Control and \\[-3mm]
+ \LARGE Privacy Policies (4)\\[-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\\
+ Of$\!$fice: & S1.27 (1st floor Strand Building)\\
+ Slides: & KEATS (also homework is there)\\
+ \end{tabular}
+ \end{center}
+
+
+\end{frame}}
+ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{Unix-Style Access Control}
+
+\begin{itemize}
+\item Q: ``I am using Windows. Why should I care?'' \\ A: In Windows you have similar AC:
+
+\begin{center}
+\begin{tabular}{l}
+administrators group\\
+\hspace{5mm}(has complete control over the machine)\\
+authenticated users\\
+server operators\\
+power users\\
+network configuration operators\\
+\end{tabular}
+\end{center}\medskip
+
+\item Modern versions of Windows have more fine-grained AC than Unix; they do not have a setuid bit, but
+have \texttt{runas} (asks for a password).\pause
+
+\item OS-provided access control can \alert{\bf add} to your
+security.
+\end{itemize}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{c}Network Applications:\\[-1mm] Privilege Separation\end{tabular}}
+
+
+\begin{center}
+ \begin{tikzpicture}[scale=1]
+
+ \draw[line width=1mm] (-.3, 0) rectangle (1.5,2);
+ \draw (4.7,1) node {Internet};
+ \draw (-2.7,1.7) node {\footnotesize Application};
+ \draw (0.6,1.7) node {\footnotesize Interface};
+ \draw (0.6,-0.4) node {\footnotesize \begin{tabular}{c}unprivileged\\[-1mm] process\end{tabular}};
+ \draw (-2.7,-0.4) node {\footnotesize \begin{tabular}{c}privileged\\[-1mm] process\end{tabular}};
+
+ \draw[line width=1mm] (-1.8, 0) rectangle (-3.6,2);
+
+ \draw[white] (1.7,1) node (X) {};
+ \draw[white] (3.7,1) node (Y) {};
+ \draw[red, <->, line width = 2mm] (X) -- (Y);
+
+ \draw[red, <->, line width = 1mm] (-0.6,1) -- (-1.6,1);
+ \end{tikzpicture}
+\end{center}
+
+\begin{itemize}
+\item the idea is make the attack surface smaller and
+mitigate the consequences of an attack
+\end{itemize}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{Shared Access Control}
+
+\begin{center}
+\includegraphics[scale=0.7]{pics/pointsplane.jpg}
+\end{center}
+
+\begin{textblock}{11}(10.5,10.5)
+\small
+To take an action you\\[-1mm]
+need at least either:
+\begin{itemize}
+\item 1 CEO\\[-5mm]
+\item 2 MDs, or\\[-5mm]
+\item 3 Ds
+\end{itemize}
+\end{textblock}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{Lessons from Access Control}
+
+Not just restricted to Unix:
+
+\begin{itemize}
+\item if you have too many roles (i.e.~too finegrained AC), then
+ hierarchy is too complex\\
+ \textcolor{gray}{you invite situations like\ldots let's be root}\bigskip
+
+\item you can still abuse the system\ldots
+
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}A ``Cron''-Attack\end{tabular}}
+
+The idea is to trick a privileged person to do something on your behalf:
+
+\begin{itemize}
+\item root:\\\texttt{rm /tmp/*/*}\bigskip\bigskip\pause
+
+\footnotesize
+\begin{minipage}{1.1\textwidth}
+\textcolor{gray}{the shell behind the scenes:}\\
+\textcolor{gray}{\texttt{rm /tmp/dir$_1$/file$_1$ /tmp/dir$_1$/file$_2$ /tmp/dir$_2$/file$_1$ \ldots}}\bigskip\\
+
+\textcolor{gray}{this takes time}
+\end{minipage}
+\end{itemize}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}A ``Cron''-Attack\end{tabular}}
+
+\begin{enumerate}
+\item attacker \textcolor{gray}{(creates a fake passwd file)}\\
+\texttt{mkdir /tmp/a; cat > /tmp/a/passwd}\medskip
+\item root \textcolor{gray}{(does the daily cleaning)}\\
+\texttt{rm /tmp/*/*}\medskip\\
+\hspace{2cm}\textcolor{gray}{\small records that \texttt{/tmp/a/passwd}}\\
+\hspace{2cm}\textcolor{gray}{\small should be deleted, but does not do it yet}\medskip\\
+
+\item attacker \textcolor{gray}{(meanwhile deletes the fake passwd file, and establishes a link to
+the real passwd file)}\\
+\texttt{rm /tmp/a/passwd; rmdir /tmp/a;}\\\texttt{ln -s /etc /tmp/a}\\
+\item root now deletes the real passwd file
+\end{enumerate}
+
+\only<2>{
+\begin{textblock}{11}(2,5)
+\begin{tikzpicture}
+\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm]
+{\normalsize\color{darkgray}
+\begin{minipage}{9cm}\raggedright
+To prevent this kind of attack, you need additional
+policies (don't do such operations as root).
+\end{minipage}};
+\end{tikzpicture}
+\end{textblock}}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}Schneier Analysis\end{tabular}}
+
+\textcolor{gray}{There is no absolutely secure system and security almost never comes for free.}
+
+\begin{itemize}
+\item What assets are you trying to protect?
+\item What are the risks to these assets?
+\item How well does the security solution mitigate those risks?
+\item What other risks does the security solution cause?
+\item What costs and trade-offs does the security solution impose?
+\end{itemize}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Example: Credit Cards\end{tabular}}
+
+You might have the policy of not typing in your credit card online. Worthwhile or not?
+\begin{itemize}
+\item<2->What assets are you trying to protect?\\
+\only<2>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}your credit card number\end{tabular}}
+\item<3->What are the risks to these assets?\\
+\only<3>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+With credit cards you loose a fixed amount \pounds{50}. Amazon \pounds{50}. \end{tabular}}
+\item<4->How well does the security solution mitigate those risks?\\
+\only<4>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Well, hackers steal credit cards from databases. They usually do not attack you individually.\end{tabular}}
+\item<5->What other risks does the security solution cause?
+\only<5>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright None (?)\end{tabular}}
+\item<6->What costs and trade-offs does the security solution impose?
+\only<6>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright Internet shopping is convenient and sometimes cheaper.\end{tabular}}
+\item<7>[]{\bf\large No!}
+\end{itemize}\pause\pause
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}Example: Firewalls\end{tabular}}
+
+\begin{center}
+\includegraphics[scale=0.5]{pics/firewall.png}
+\end{center}
+
+A firewall is a piece of software that controls incoming and outgoing traffic according to some rules.
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Example: Firewalls\end{tabular}}
+
+\begin{itemize}
+\item<1->What assets are you trying to protect?\\
+\only<1>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}Whatever is behind the firewall
+(credit cards, passwords, blueprints, \ldots)\end{tabular}}
+\item<2->What are the risks to these assets?\\
+\only<2>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+With a small online shop you are already at risk. Pentagon, definitely.\end{tabular}}
+\item<3->How well does the security solution mitigate those risks?\\
+\only<3>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Well, at home so not much. Everywhere else, if properly configurated then it does.\end{tabular}}
+\item<4->What other risks does the security solution cause?
+\only<4>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright There might be backdoors or bugs in the firewall,
+but generally they are secure. You choose to prevent certain traffic.\end{tabular}}
+\item<5->What costs and trade-offs does the security solution impose?
+\only<5>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Minimal to modest. Firewalls are part of free software. You need a knowledgeable
+person to set them up.\end{tabular}}
+\item<7>[]{\bf\large Yes!}
+\end{itemize}\pause\pause
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Ex: Two-Factor Authentication\end{tabular}}
+
+Google uses nowadays two-factor authentication. But it is an old(er)
+idea. It is used for example in Germany and Netherlands for online transactions.
+
+\begin{center}
+\includegraphics[scale=0.6]{pics/tan1.jpg}\hspace{5mm}
+\includegraphics[scale=0.2]{pics/tan2.jpg}
+\end{center}
+
+\pause
+Or nowadays by SMS (restricts the validity of the numbers) or with a secure generator
+
+\begin{center}
+\includegraphics[scale=0.08]{pics/pinsentry.jpg}
+\end{center}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Ex: Two-Factor Authentication\end{tabular}}
+
+\begin{itemize}
+\item<1->What assets are you trying to protect?\\
+\only<1>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}Your bank account.\end{tabular}}
+\item<2->What are the risks to these assets?\\
+\only<2>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Nowadays pretty high risk.\end{tabular}}
+\item<3->How well does the security solution mitigate those risks?\\
+\only<3>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+It prevents problems when passwords are stolen. Man-in-the-middle attacks
+still possible.\end{tabular}}
+\item<4->What other risks does the security solution cause?
+\only<4>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright Your mobile phone or credit card/pin might
+be stolen. SIM card becomes more valuable.\end{tabular}}
+\item<5->What costs and trade-offs does the security solution impose?
+\only<5>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Banks need to establish an infrastructure. For you it might be inconvenient.\end{tabular}}
+\item<7>[]{\bf\large Yes!}
+\end{itemize}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Security Seals\end{tabular}}
+
+According to Ross Anderson: ``\ldots is a tamper-indicating device
+designed to leave non-erasable, unambiguous evidence of unauthorized
+entry or tampering.''
+
+\begin{center}
+\includegraphics[scale=0.45]{pics/seal.jpg}
+\end{center}\mbox{}\\[-12mm]
+
+They also need some quite sophisticated policies (seal regiment).
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Security Seals (2)\end{tabular}}
+
+\begin{itemize}
+\item at the Argonne National Laboratory they tested 244 different security seals
+\begin{itemize}
+\item meantime to break the seals for a trained person: 100 s
+\item including 19\% that were used for safeguard of nuclear material
+\end{itemize}\bigskip
+
+\item Andrew Appel defeated all security seals which were supposed to keep
+voting machines safe
+\end{itemize}
+
+
+\only<2>{
+\begin{textblock}{11}(1,1)
+\begin{tikzpicture}
+\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm]
+{\normalsize
+\begin{minipage}{11cm}\raggedright\small
+\begin{center}
+\includegraphics[scale=0.25]{pics/appelseals.jpg}
+\end{center}
+\begin{center}
+\begin{minipage}{10.5cm}
+\begin{itemize}
+\item The tamper-indicating tape can be lifted using a heat gun.
+\item The security screw cap can be removed using a screwdriver, then the
+serial-numbered top can be replaced (undamaged) onto a fresh (unnumbered) base.
+\item The wire seal can be defeated using a \#4 wood screw.
+\item The plastic strap seal can be picked using a jeweler's screwdriver.
+\end{itemize}
+\end{minipage}
+\end{center}
+\end{minipage}};
+\end{tikzpicture}
+\end{textblock}}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Example: Security Seals\end{tabular}}
+
+\begin{itemize}
+\item<1->What assets are you trying to protect?\\
+\only<1>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}Voting machines, doors.\end{tabular}}
+\item<2->What are the risks to these assets?\\
+\only<2>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright Casual thieves, insider attacks.\end{tabular}}
+\item<3->How well does the security solution mitigate those risks?\\
+\only<3>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Needs a quite complicated security regiment.\end{tabular}}
+\item<4->What other risks does the security solution cause?
+\only<4>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright You might not notice tampering.\end{tabular}}
+\item<5->What costs and trade-offs does the security solution impose?
+\only<5>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+The ``hardware'' is cheap, but indirect costs can be quite high.\end{tabular}}
+\item<7>[]{\bf\large No!} {\textcolor{gray}{Though in some areas they work: airports, swimming pools, \ldots}}
+\end{itemize}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Ex: Security-by-Obscurity\end{tabular}}
+
+You might think it is a good idea to keep a security relevant algorithm or
+software secret.
+
+\begin{itemize}
+\item<1->What assets are you trying to protect?\\
+\only<1>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}Source code, an algorithm and things that depend on it\end{tabular}}
+\item<2->What are the risks to these assets?\\
+\only<2>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Can be pretty high (Oystercards).\end{tabular}}
+\item<3->How well does the security solution mitigate those risks?\\
+\only<3>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright
+Not really. The source code can be reverse engineered, stolen, coerced \ldots{}\end{tabular}}
+\item<4->What other risks does the security solution cause?
+\only<4>{\begin{tabular}{@{\hspace{1cm}}p{9cm}}\raggedright You prevent
+scrutiny and independent advice. You also more likely than not to
+get it wrong.\end{tabular}}
+\item<5>[]{\bf\large No!}
+\end{itemize}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Voting as Security Problem\end{tabular}}
+
+What are the security requirements of a voting system?\bigskip
+
+\begin{itemize}
+\item<2->Integrity
+\item<3->Ballot Secrecy
+\item<5->Voter Authentication
+\item<6->Enfranchisement
+\item<7->Availability
+\end{itemize}
+
+\only<2>{
+\begin{textblock}{5.5}(8,5)
+\begin{tikzpicture}
+\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm, text centered]
+{\small
+\begin{minipage}{5cm}\raggedright
+\begin{center}
+\begin{minipage}{4.5cm}
+\begin{itemize}
+\item The outcome matches with the voters' intend.
+\item There might be gigantic sums at stake and need to be defended against.
+\end{itemize}
+\end{minipage}
+\end{center}
+\end{minipage}};
+\end{tikzpicture}
+\end{textblock}}
+
+\only<4>{
+\begin{textblock}{5.5}(8,5)
+\begin{tikzpicture}
+\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm, text centered]
+{\small
+\begin{minipage}{5cm}\raggedright
+\begin{center}
+\begin{minipage}{4.5cm}
+\begin{itemize}
+\item Nobody can find out how you voted.
+\item (Stronger) Even if you try, you cannot prove how you voted.
+\end{itemize}
+\end{minipage}
+\end{center}
+\end{minipage}};
+\end{tikzpicture}
+\end{textblock}}
+
+\only<5>{
+\begin{textblock}{5.5}(8,5)
+\begin{tikzpicture}
+\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm, text centered]
+{\small
+\begin{minipage}{5cm}\raggedright
+\begin{center}
+\begin{minipage}{4.5cm}
+\begin{itemize}
+\item Only authorised voters can vote up to the permitted number of votes.
+\end{itemize}
+\end{minipage}
+\end{center}
+\end{minipage}};
+\end{tikzpicture}
+\end{textblock}}
+
+\only<6>{
+\begin{textblock}{5.5}(8,5)
+\begin{tikzpicture}
+\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm, text centered]
+{\small
+\begin{minipage}{5cm}\raggedright
+\begin{center}
+\begin{minipage}{4.5cm}
+\begin{itemize}
+\item Authorised voters should have the opportunity to vote.
+\end{itemize}
+\end{minipage}
+\end{center}
+\end{minipage}};
+\end{tikzpicture}
+\end{textblock}}
+
+\only<7>{
+\begin{textblock}{5.5}(8,5)
+\begin{tikzpicture}
+\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm, text centered]
+{\small
+\begin{minipage}{5cm}\raggedright
+\begin{center}
+\begin{minipage}{4.5cm}
+\begin{itemize}
+\item The voting system should accept all authorised votes and produce results in a timely manner.
+\end{itemize}
+\end{minipage}
+\end{center}
+\end{minipage}};
+\end{tikzpicture}
+\end{textblock}}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Ballot Boxes\end{tabular}}
+
+
+\begin{center}
+\includegraphics[scale=2.5]{pics/ballotbox.jpg}
+\end{center}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Problems with Voting\end{tabular}}
+
+
+\begin{center}\large
+\begin{tabular}{rcl}
+Integrity & vs. & Ballot Secrecy\bigskip\\
+Authentication & vs. &Enfranchisement
+\end{tabular}
+\end{center}\bigskip\bigskip\pause
+
+Further constraints:
+
+\begin{itemize}
+\item costs
+\item accessibility
+\item convenience
+\item intelligibility
+\end{itemize}
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}E-Voting\end{tabular}}
+
+
+\begin{itemize}
+\item The Netherlands between 1997 - 2006 had electronic voting machines\\
+\textcolor{gray}{(hacktivists had found: they can be hacked and also emitted radio signals revealing how you voted)}
+
+\item Germany had used them in pilot studies\\
+\textcolor{gray}{(in 2007 a law suit has reached the highest court and it rejected electronic voting
+on the grounds of not being understandable by the general public)}
+
+\item UK used optical scan voting systems in a few polls
+\end{itemize}
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}E-Voting\end{tabular}}
+
+\mbox{}\\[-12mm]
+\begin{itemize}
+\item US used mechanical machines since the 30s, later punch cards, now DREs and
+optical scan voting machines \textcolor{gray}{(fantastic ``ecosystem'' for study)}
+
+\item Estonia used in 2007 the Internet for national elections
+\textcolor{gray}{(there were earlier pilot studies in other countries)}
+
+\item India uses e-voting devices since at least 2003\\
+\textcolor{gray}{(``keep-it-simple'' machines produced by a government owned company)}
+
+\item South Africa used software for its tallying in the 1993 elections (when Nelson Mandela was elected)
+\textcolor{gray}{(they found the tallying software was rigged, but they were able to tally manually)}
+\end{itemize}
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}A Brief History of Voting\end{tabular}}
+
+
+\begin{itemize}
+\item Athenians
+\begin{itemize}
+\item show of hands
+\item ballots on pieces of pottery
+\item different colours of stones
+\item ``facebook''-like authorisation
+\end{itemize}\bigskip
+
+\textcolor{gray}{problems with vote buying / no ballot privacy}\bigskip
+
+
+\item French Revolution and the US Constitution got things ``started'' with
+paper ballots (you first had to bring your own; later they were pre-printed by parties)
+\end{itemize}
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Ballot Boxes\end{tabular}}
+
+Security policies involved with paper ballots:
+
+\begin{enumerate}
+\item you need to check that the ballot box is empty at the start of the poll / no false bottom (to prevent ballot stuffing)
+\item you need to guard the ballot box during the poll until counting
+\item tallied by a team at the end of the poll (independent observers)
+\end{enumerate}
+
+\begin{center}
+\includegraphics[scale=1.5]{pics/ballotbox.jpg}
+\end{center}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Paper Ballots\end{tabular}}
+
+What can go wrong with paper ballots?
+
+\only<2>{
+\begin{center}
+\includegraphics[scale=0.8]{pics/tweet.jpg}\\
+\footnotesize William M.~Tweed, US Politician in 1860's\\
+``As long as I count the votes, what are you going to do about it?''
+\end{center}}
+
+\only<3>{
+\medskip
+\begin{center}
+\begin{minipage}{10cm}
+{\bf Chain Voting Attack}
+\begin{enumerate}
+\item you obtain a blank ballot and fill it out as you want
+\item you give it to a voter outside the polling station
+\item voter receives a new blank ballot
+\item voter submits prefilled ballot
+\item voter gives blank ballot to you, you give money
+\item goto 1
+\end{enumerate}
+\end{minipage}
+\end{center}
+}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Mechanical Voting Machines\end{tabular}}
+
+\begin{itemize}
+\item<1-> Lever Voting Machines (ca.~1930 - 1990)
+\only<1>{
+\begin{center}
+\includegraphics[scale=0.56]{pics/leavermachine.jpg}
+\end{center}
+}
+\item<2->Punch Cards (ca.~1950 - 2000)
+\only<2>{
+\begin{center}
+\includegraphics[scale=0.5]{pics/punchcard1.jpg}\;\;
+\includegraphics[scale=0.46]{pics/punchcard2.jpg}
+\end{center}
+}
+\end{itemize}
+
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[t]
+\frametitle{\begin{tabular}{@ {}c@ {}}Electronic Voting Machines\end{tabular}}
+
+\begin{center}
+\begin{tabular}{c}
+\includegraphics[scale=0.45]{pics/dre1.jpg}\;
+\includegraphics[scale=0.40]{pics/dre2.jpg}\\\hline\\
+\includegraphics[scale=0.5]{pics/opticalscan.jpg}
+\end{tabular}
+\end{center}
+
+\only<1->{
+\begin{textblock}{5.5}(1,4)
+DREs
+\end{textblock}}
+\only<1->{
+\begin{textblock}{5.5}(1,11)
+Optical Scan
+\end{textblock}}
+
+\only<2>{
+\begin{textblock}{5.5}(0.5,14.5)
+all are computers
+\end{textblock}}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}DREs\end{tabular}}
+
+Direct-recording electronic voting machines\\
+(votes are recorded for example memory cards)
+
+typically touchscreen machines
+
+usually no papertrail (hard to add: ballot secrecy)
+
+\begin{center}
+\includegraphics[scale=0.56]{pics/dre1.jpg}
+\end{center}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}Diebold Machines\end{tabular}}
+
+The work by J.~Alex Halderman:
+
+\begin{itemize}
+\item acquired a machine from an anonymous source\medskip
+\item the source code running the machine was tried to keep secret\medskip\pause
+
+\item first reversed-engineered the machine (extremely tedious)
+\item could completely reboot the machine and even install a virus that infects other Diebold machines
+\item obtained also the source code for other machines
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}Diebold Machines\end{tabular}}
+
+What could go wrong?\pause \;\;Failure-in-depth.\bigskip\pause
+
+A non-obvious problem:
+
+\begin{itemize}
+\item you can nowadays get old machines, which still store old polls
+
+\item the paper ballot box needed to be secured during the voting until counting;
+e-voting machines need to be secured during the entire life-time
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}Paper Trail\end{tabular}}
+
+Conclusion:\\ Any electronic solution should have a paper trail.
+
+\begin{center}
+\begin{tabular}{c}
+\includegraphics[scale=0.5]{pics/opticalscan.jpg}
+\end{tabular}
+\end{center}\pause
+
+You still have to solve problems about
+Voter registration, voter authentification, guarding against tampering
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}E-Voting in India\end{tabular}}
+
+Their underlying engineering principle is ``keep-it-simple'':
+
+\begin{center}
+\begin{tabular}{c}
+\includegraphics[scale=1.05]{pics/indiaellection.jpg}\;\;
+\includegraphics[scale=0.40]{pics/india1.jpg}
+\end{tabular}
+\end{center}\medskip\pause
+
+Official claims: ``perfect'', ``tamperproof'', ``no need for technical improvements'' , ``infallible''
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+\frametitle{\begin{tabular}{@ {}c@ {}}Lessons to be Learned\end{tabular}}
+
+\begin{itemize}
+\item keep a paper trail and design your system to keep this secure\medskip
+\item make the software open source (avoid security-by-obscurity))\medskip
+\item have a simple design in order to minimise the attack surface
+\end{itemize}
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+
+\begin{center}
+\includegraphics[scale=0.56]{pics/Voting1.png}
+\end{center}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+
+\begin{center}
+\includegraphics[scale=0.56]{pics/Voting2.png}
+\end{center}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+
+\begin{center}
+\includegraphics[scale=0.56]{pics/Voting3.png}
+\end{center}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\mode<presentation>{
+\begin{frame}[c]
+
+\begin{center}
+\includegraphics[scale=0.56]{pics/Voting4.png}
+\end{center}
+
+
+\end{frame}}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\end{document}
+
+%%% Local Variables:
+%%% mode: latex
+%%% TeX-master: t
+%%% End:
+