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\begin{frame}[t]

\frametitle{%

  \begin{tabular}{@ {}c@ {}}

  \\

  \LARGE Access Control and \\[-3mm] 

  \LARGE Privacy Policies (10)\\[-6mm] 

  \end{tabular}}\bigskip\bigskip\bigskip

  \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}

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\begin{frame}[c]

\frametitle{\begin{tabular}{c}\mbox{}\\[20mm]\Huge Revision\end{tabular}}

\end{frame}

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\begin{frame}[c]

\frametitle{Security Engineering}

  \begin{center}

  \begin{tabular}{cc}

  \raisebox{-0.8mm}{\includegraphics[scale=0.28]{../pics/flight.jpg}} &

  \includegraphics[scale=0.31]{../pics/airbus.jpg}\\

  \small Wright brothers, 1901 & \small Airbus, 2005 \\ 

  \end{tabular}

  \end{center}

  \end{frame}

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\begin{frame}[c]

\frametitle{1st Lecture}

\begin{itemize}

\item chip-and-pin, banks vs.~customers

\begin{quote}\small\rm

 the one who can improve security should also be 

 liable for the losses 

\end{quote}\pause\bigskip

\item hashes and salts to guarantee data integrity\medskip

\item storing passwords (you should know the difference between

brute force attacks and dictionary attacks; how do salts help?)

\end{itemize}

\end{frame}

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\begin{frame}[c]

\frametitle{1st Lecture: Cookies}

\begin{itemize}

\item good uses of cookies?\medskip

\item bad uses of cookies: snooping, tracking, profiling\ldots

      the ``disadvantage'' is that the user is in

      \alert{control}, because you can delete them 

          \begin{center} ``Please track me using cookies.''

          \end{center}\bigskip\pause

\item fingerprinting beyond browser cookies

  \begin{quote}\small\rm

  Pixel Perfect: Fingerprinting Canvas in HTML5\\ 

  (a research paper from 2012)\\

  \footnotesize

  \url{http://cseweb.ucsd.edu/~hovav/papers/ms12.html}      

  \end{quote}      

\end{itemize}

\end{frame}

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\begin{frame}[c]

\frametitle{1st Lecture: Cookies}

\begin{itemize}

\item a bit of JavaScript and HTML5 + canvas\medskip

\begin{center}

\begin{tabular}{cc}

Firefox & Safari\\

\includegraphics[scale=0.31]{../pics/firefox1.png} &

\includegraphics[scale=0.31]{../pics/safari1.png} \\

\tiny

\pcode{55b2257ad0f20ecbf927fb66a15c61981f7ed8fc} &

\tiny

\pcode{17bc79f8111e345f572a4f87d6cd780b445625d3}

\end{tabular}

\end{center}\bigskip

\item\small no actual drawing needed\pause

\item\small in May 2014 a crawl of 100,000 popular 

webpages revealed 5.5\% already use canvas 

fingerprinting\smallskip

\begin{center}\scriptsize

\url{https://securehomes.esat.kuleuven.be/~gacar/persistent/the_web_never_forgets.pdf}

\end{center}

\end{itemize}

\end{frame}

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\begin{frame}[c]

\frametitle{1st Lecture: Cookies}

Remember the small web-app I showed where a cookie 

protected a counter\bigskip 

\begin{itemize}

\item NYT, the cookie looks the ``resource'' - harm\medskip

\item imaginary discount unlocked by cookie - no harm

\end{itemize}

\end{frame}

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\begin{frame}[t]

\frametitle{2nd Lecture: E-Voting}

Where are paper ballots better than voice voting?\bigskip

\begin{itemize}

\item Integrity 

\item \alert{Ballot Secrecy}

\item Voter Authentication

\item Enfranchisement

\item Availability

\end{itemize}

\end{frame}

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\begin{frame}[t]

\frametitle{2nd Lecture: E-Voting}

\begin{itemize}

\item (two weeks ago) an Australian parliamentary committee 

found: e-voting is highly vulnerable to hacking and Australia 

will not use it any time soon\bigskip\pause

\item Alex Halderman, Washington D.C.~hack

\begin{center}

\scriptsize

\url{https://jhalderm.com/pub/papers/dcvoting-fc12.pdf}

\end{center}\medskip

\item PDF-ballot tampering at the wireless router (the modification 

is nearly undetectable and leaves no traces; MITM attack with firmware 

updating)

\begin{center}

\scriptsize

\url{http://galois.com/wp-content/uploads/2014/11/technical-hack-a-pdf.pdf}

\end{center}

\end{itemize}

\end{frame}

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\begin{frame}[t]

\frametitle{\begin{tabular}{c}3rd Lecture:\\ Buffer Overflow Attacks\end{tabular}}

\begin{itemize}

\item the problem arises from the way C/C++ organises its function calls\\[-8mm]\mbox{}

\end{itemize}

\begin{center}

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\begin{frame}[t]

\frametitle{\begin{tabular}{c}3rd Lecture:\\[-3mm] 

Buffer Overflow Attacks\end{tabular}}

US National Vulnerability Database\\ 

\small(636 out of 6675 in 2014)

\begin{center}

\begin{tikzpicture}

\begin{axis}[

    xlabel={year},

    ylabel={\% of total attacks},

    ylabel style={yshift=0em},

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    xtick={1997,1998,2000,...,2014},

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    xmax=2015,

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\addplot

  table [x=Year,y=Percentage] {bufferoverflows.data};

\end{axis}

\end{tikzpicture}

\end{center}

\scriptsize

\url{http://web.nvd.nist.gov/view/vuln/statistics}

\end{frame}

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\begin{frame}[t]

\frametitle{\begin{tabular}{c}4th Lecture:\\ Unix Access Control\end{tabular}}

\begin{itemize}

\item privileges are specified by file access permissions (``everything is a file'') 

\end{itemize}\medskip

\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}};

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  \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 to make the attack surface smaller and 

mitigate the consequences of an attack

\end{itemize}

\end{frame}

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\begin{frame}[fragile,t]

\frametitle{\begin{tabular}{c}4th Lecture:\\ Unix Access Control\end{tabular}}

\begin{itemize}

\item when a file with setuid is executed, the resulting process will assume the 

UID given to the owner of the file

\end{itemize}

\footnotesize\tt

\begin{center}

\begin{verbatim}

$ ls -ld . * */*

drwxr-xr-x 1 ping staff  32768 Apr  2 2010 .

-rw----r-- 1 ping students  31359 Jul 24 2011 manual.txt

-r--rw--w- 1 bob students    4359 Jul 24 2011 report.txt

-rwsr--r-x 1 bob students  141359 Jun  1 2013 microedit

dr--r-xr-x 1 bob staff      32768 Jul 23 2011 src

-rw-r--r-- 1 bob staff      81359 Feb 28 2012 src/code.c

-r--rw---- 1 emma students    959 Jan 23 2012 src/code.h

\end{verbatim}

\end{center}

\end{frame}

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\begin{frame}[t]

\frametitle{\begin{tabular}{c}4th Lecture:\\ Unix Access Control\end{tabular}}

\begin{itemize}

\item Alice wants to have her files readable, 

\alert{except} for her office mates.

\end{itemize}

\end{frame}

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\begin{frame}[c]

\frametitle{5rd Lecture: Protocols}

Simple Challenge Response\\

(solving the replay problem):

\begin{center}

\begin{tabular}{lll}

\bl{$A \rightarrow B:$} & \bl{Hi I am A}\\

\bl{$B \rightarrow A:$} & \bl{$N$} & (challenge)\\

\bl{$A \rightarrow B:$} & \bl{$\{N\}_{K_{AB}}$}\\

\end{tabular} 

\end{center}\pause

Mutual Challenge Response:

\begin{center}

\begin{tabular}{ll}

\bl{$A \rightarrow B:$} & \bl{$N_A$}\\

\bl{$B \rightarrow A:$} & \bl{$\{N_A, N_B\}_{K_{AB}}$}\\

\bl{$A \rightarrow B:$} & \bl{$N_B$}\\

\end{tabular} 

\end{center}

\end{frame}

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\begin{frame}[c]

\frametitle{5rd Lecture: Protocols}

A car-transponder protocol:

\begin{enumerate}

\item \bl{$C$} generates a random number \bl{$N$}

\item \bl{$C$} calculates \bl{$(F,G) = \{N\}_K$}

\item \bl{$C \to T$}: \bl{$N, F$}

\item \bl{$T$} calculates \bl{$(F',G') = \{N\}_K$}

\item \bl{$T$} checks that \bl{$F = F'$}

\item \bl{$T \to C$}: \bl{$N, G'$}

\item \bl{$C$} checks that \bl{$G = G'$}

\end{enumerate}

Authentication: \bl{$T \to C$}, \bl{$C \to T$}?

\end{frame}

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\begin{frame}[c]

\frametitle{5rd Lecture: Protocols}

The interlock protocol (``best bet'' against MITM):

\begin{center}

\begin{tabular}{ll@{\hspace{2mm}}l}

1. & \bl{$A \to B :$} & \bl{$K^{pub}_A$}\\

2. & \bl{$B \to A :$} & \bl{$K^{pub}_B$}\\

3. & & \bl{$\{A,m\}_{K^{pub}_B} \;\mapsto\; H_1,H_2$}\\

   & & \bl{$\{B,m'\}_{K^{pub}_A} \;\mapsto\; M_1,M_2$}\\

4. & \bl{$A \to B :$} & \bl{$H_1$}\\

5. & \bl{$B \to A :$} & \bl{$\{H_1, M_1\}_{K^{pub}_A}$}\\

6. & \bl{$A \to B :$} & \bl{$\{H_2, M_1\}_{K^{pub}_B}$}\\

7. & \bl{$B \to A :$} & \bl{$M_2$}

\end{tabular}

\end{center}\pause

\footnotesize

\bl{$m$} = How is your grandmother? \bl{$m'$} = How is the

weather today in London?

\end{frame}

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