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\renewcommand{\slidecaption}{APP 09, King's College London, 10 December 2013}

  Office: & S1.27 (1st floor Strand Building)\\

\frametitle{\mbox{}\\[20mm]\huge Revision}

\frametitle{1st Lecture}

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\frametitle{\begin{tabular}{c}2nd Lecture:\\ E-Voting\end{tabular}}

\begin{itemize}

\item Integrity 

\item Ballot Secrecy

\item Voter Authentication

\item Enfranchisement

\item Availability

\end{itemize}

\end{frame}

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\begin{frame}[fragile,t]

\frametitle{\begin{tabular}{c}2nd Lecture:\\ E-Voting\end{tabular}}

Online Banking vs.~E-Voting

\begin{itemize}

\item online banking: if fraud occurred you try to identify who did what (somebody's account got zero)\bigskip

\item e-voting: some parts can be done electronically, but not the actual voting (final year project: online voting)

\end{itemize}

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\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}

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\frametitle{\begin{tabular}{c}3rd Lecture:\\ Unix Access Control\end{tabular}}

\begin{itemize}

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

\end{itemize}\medskip

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\begin{itemize}

\item the idea is make the attack surface smaller and 

mitigate the consequences of an attack

\end{itemize}

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\frametitle{\begin{tabular}{c}3rd 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}

\small\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}

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\frametitle{\begin{tabular}{c}4th Lecture:\\ Security Levels\end{tabular}}

Bell-LaPadula access model:

 \begin{itemize}

  \item \alert{Read Rule}: A principal \bl{$P$} can read an object \bl{$O$} if and only if

  \bl{$P$}'s security level is at least as high as \bl{$O$}'s.

  \item \alert{Write Rule}: A principal \bl{$P$} can write an object \bl{$O$} if and only if

  \bl{$O$}'s security level is at least as high as \bl{$P$}'s.\medskip

  \item Meta-Rule: All principals in a system should have a sufficiently high security level

  in order to access an object.

  \end{itemize}\bigskip

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\frametitle{\begin{tabular}{c}4th Lecture:\\ Security Levels\end{tabular}}

Biba (data integrity)

  \begin{itemize}

  \item Biba: {\bf `no read down'} - {\bf `no write up'}

  \item \alert{Read Rule}: A principal \bl{$P$} can read an object \bl{$O$} if and only if

  \bl{$P$}'s security level is lower or equal than \bl{$O$}'s.

  \item \alert{Write Rule}: A principal \bl{$P$} can write an object \bl{$O$} if and only if

  \bl{$O$}'s security level is lower or equal than \bl{$P$}'s.

  \end{itemize}

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\frametitle{\begin{tabular}{c}4th Lecture:\\ Protocols\end{tabular}}

A mutual authentication protocol

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\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{$N_b$}\\

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\frametitle{\begin{tabular}{c}5th Lecture:\\ Access Control Logic\end{tabular}}

\begin{itemize}

\item formulas

\item judgements

\end{itemize}\pause

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\frametitle{\begin{tabular}{c}6th Lecture:\\ Privacy\end{tabular}}

\end{frame}}

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