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\documentclass[dvipsnames,14pt,t]{beamer}
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\usepackage{proof}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\usepackage{beamerthemeplaincu}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%\usepackage[T1]{fontenc}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%\usepackage[latin1]{inputenc}
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\usepackage{mathpartir}
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\usepackage{isabelle}
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\usepackage{isabellesym}
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\usepackage[absolute,overlay]{textpos}
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\usepackage{ifthen}
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\usepackage{tikz}
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\usepackage{courier}
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\usepackage{listings}
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\usetikzlibrary{arrows}
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\usetikzlibrary{positioning}
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\usetikzlibrary{calc}
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\usepackage{graphicx}
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\usetikzlibrary{shapes}
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\usetikzlibrary{shadows}
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\usetikzlibrary{plotmarks}
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\isabellestyle{rm}
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\renewcommand{\isastyle}{\rm}%
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\renewcommand{\isastyleminor}{\rm}%
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\renewcommand{\isastylescript}{\footnotesize\rm\slshape}%
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\renewcommand{\isatagproof}{}
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\renewcommand{\endisatagproof}{}
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\renewcommand{\isamarkupcmt}[1]{#1}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\newcommand{\isaliteral}[1]{}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\newcommand{\isactrlisub}[1]{\emph{\isascriptstyle${}\sb{#1}$}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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% Isabelle characters
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\renewcommand{\isacharunderscore}{\_}
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\renewcommand{\isacharbar}{\isamath{\mid}}
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\renewcommand{\isasymiota}{}
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\renewcommand{\isacharbraceleft}{\{}
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\renewcommand{\isacharbraceright}{\}}
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\renewcommand{\isacharless}{$\langle$}
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\renewcommand{\isachargreater}{$\rangle$}
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\renewcommand{\isasymsharp}{\isamath{\#}}
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\renewcommand{\isasymdots}{\isamath{...}}
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\renewcommand{\isasymbullet}{\act}
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\definecolor{javared}{rgb}{0.6,0,0} % for strings
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\definecolor{javagreen}{rgb}{0.25,0.5,0.35} % comments
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\definecolor{javapurple}{rgb}{0.5,0,0.35} % keywords
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\definecolor{javadocblue}{rgb}{0.25,0.35,0.75} % javadoc
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\lstset{language=Java,
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basicstyle=\ttfamily,
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keywordstyle=\color{javapurple}\bfseries,
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stringstyle=\color{javagreen},
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commentstyle=\color{javagreen},
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morecomment=[s][\color{javadocblue}]{/**}{*/},
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numbers=left,
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numberstyle=\tiny\color{black},
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stepnumber=1,
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numbersep=10pt,
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tabsize=2,
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showspaces=false,
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showstringspaces=false}
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\lstdefinelanguage{scala}{
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morekeywords={abstract,case,catch,class,def,%
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do,else,extends,false,final,finally,%
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for,if,implicit,import,match,mixin,%
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new,null,object,override,package,%
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private,protected,requires,return,sealed,%
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super,this,throw,trait,true,try,%
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type,val,var,while,with,yield},
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otherkeywords={=>,<-,<\%,<:,>:,\#,@},
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sensitive=true,
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morecomment=[l]{//},
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morecomment=[n]{/*}{*/},
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morestring=[b]",
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morestring=[b]',
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morestring=[b]"""
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}
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\lstset{language=Scala,
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basicstyle=\ttfamily,
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keywordstyle=\color{javapurple}\bfseries,
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stringstyle=\color{javagreen},
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commentstyle=\color{javagreen},
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morecomment=[s][\color{javadocblue}]{/**}{*/},
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numbers=left,
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numberstyle=\tiny\color{black},
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stepnumber=1,
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numbersep=10pt,
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tabsize=2,
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showspaces=false,
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showstringspaces=false}
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% beamer stuff
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\renewcommand{\slidecaption}{APP 07, King's College London, 19 November 2013}
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\newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}% for definitions
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\newcommand{\bl}[1]{\textcolor{blue}{#1}}
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\begin{document}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\mode<presentation>{
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\begin{frame}<1>[t]
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\frametitle{%
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\begin{tabular}{@ {}c@ {}}
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\\
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\LARGE Access Control and \\[-3mm]
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\LARGE Privacy Policies (7)\\[-6mm]
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\end{tabular}}\bigskip\bigskip\bigskip
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%\begin{center}
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%\includegraphics[scale=1.3]{pics/barrier.jpg}
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%\end{center}
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\normalsize
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\begin{center}
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\begin{tabular}{ll}
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Email: & christian.urban at kcl.ac.uk\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Office: & S1.27 (1st floor Strand Building)\\
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Slides: & KEATS (also homework is there)\\
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\end{tabular}
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\end{center}
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\end{frame}}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\mode<presentation>{
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\begin{frame}[c]
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\frametitle{}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Recall the following scenario:
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{itemize}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item If \textcolor{blue}{Admin} says that \textcolor{blue}{\isa{file}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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should be deleted, then this file must be deleted.
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item \textcolor{blue}{Admin} trusts \textcolor{blue}{Bob} to decide whether
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\textcolor{blue}{\isa{file}} should be deleted (delegation).
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item \textcolor{blue}{Bob} wants to delete \textcolor{blue}{\isa{file}}.
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{itemize}\bigskip
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\small
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\textcolor{blue}{\isa{{\isaliteral{5C3C47616D6D613E}{\isasymGamma}}\ {\isaliteral{3D}{\isacharequal}}}\small\begin{tabular}{l}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\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}{}},\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\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}}},\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\isa{Bob\ says\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}}\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{tabular}}\medskip
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\textcolor{blue}{\isa{{\isaliteral{5C3C47616D6D613E}{\isasymGamma}}\ {\isaliteral{5C3C7475726E7374696C653E}{\isasymturnstile}}\ del{\isaliteral{5F}{\isacharunderscore}}file\isaliteral{5C3C5E697375623E}{}}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{frame}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\mode<presentation>{
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{frame}[c]
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\frametitle{\begin{tabular}{@ {\hspace{-2mm}}c@ {}}The Access Control Problem\end{tabular}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{center}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{tikzpicture}[scale=1]
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw[line width=1mm] (-.3, -0.5) rectangle (1.5,2);
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw (-2.7,1) node {\begin{tabular}{l}access\\request\\ (\bl{$F$})\end{tabular}};
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw (4.2,1) node {\begin{tabular}{l}provable/\\not provable\end{tabular}};
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw (0.6,0.8) node {\footnotesize \begin{tabular}{l}AC-\\ Checker:\\ applies\\ inference\\ rules\end{tabular}};
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw[red, ->, line width = 2mm] (1.7,1) -- (2.7,1);
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw[red,<-, line width = 2mm] (-0.6,1) -- (-1.6,1);
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw[red, <-, line width = 3mm] (0.6,2.2) -- (0.6,3.2);
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\draw (0.6,4) node {\begin{tabular}{l}\large Access Policy (\boldmath\bl{$\Gamma$})\end{tabular}};
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{tikzpicture}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{center}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{frame}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\mode<presentation>{
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{frame}[c]
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{itemize}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item \bl{$P \,\text{says}\, F$} means \bl{$P$} can send a ``signal'' \bl{$F$} through a wire, or
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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can make a ``statement'' \bl{$F$}\bigskip\pause
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item \bl{$P$} is entitled to do \bl{$F$}\smallskip\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\bl{$P \,\text{controls}\, F \,\dn\, (P\,\text{says}\, F) \Rightarrow F$}\medskip
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{center}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\bl{\infer{\Gamma \vdash F}{\Gamma \vdash P\,\text{controls}\, F & \Gamma \vdash P\,\text{says}\,F}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{center}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{itemize}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{frame}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\mode<presentation>{
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\begin{frame}[c]
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\frametitle{Security Levels}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\small
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{itemize}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item Top secret (\bl{$T\!S$})
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item Secret (\bl{$S$})
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item Public (\bl{$P$})
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\end{itemize}
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\begin{center}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\bl{$slev(P) < slev(S) < slev(T\!S)$}\pause
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\end{center}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{itemize}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item Bob has a clearance for ``secret''
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\item Bob can read documents that are public or sectret, but not top secret
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\end{itemize}
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\end{frame}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\mode<presentation>{
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{frame}[c]
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\frametitle{Reading a File}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\bl{\begin{center}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{tabular}{c}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\begin{tabular}{@ {}l@ {}}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\only<2->{\textcolor{red}{$slev($File$)$ $<$ $slev($Bob$)$ $\Rightarrow$}}\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\only<2->{\hspace{3cm}}Bob controls Permitted $($File, read$)$\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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240 |
Bob says Permitted $($File, read$)$\only<2->{\\}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\only<2>{\textcolor{red}{$slev($File$)$ $<$ $slev($Bob$)$}}%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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\only<3>{\textcolor{red}{$slev($File$)$ $=$ $P$}\\}%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
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243 |
\only<3>{\textcolor{red}{$slev($Bob$)$ $=$ $S$}\\}%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
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244 |
\only<3>{\textcolor{red}{$slev(P)$ $<$ $slev(S)$}\\}%
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Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
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245 |
\end{tabular}\\
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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246 |
\hline
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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247 |
Permitted $($File, read$)$
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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248 |
\end{tabular}
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Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
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|
249 |
\end{center}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
250 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
251 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
252 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
253 |
%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
254 |
|
66
|
255 |
|
65
|
256 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
67
|
257 |
\mode<presentation>{
|
|
258 |
\begin{frame}[c]
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
259 |
\frametitle{Substitution Rule}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
260 |
\small
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
261 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
262 |
\bl{\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
263 |
\begin{tabular}{c}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
264 |
$\Gamma \vdash slev(P) = l_1$ \hspace{4mm} $\Gamma \vdash slev(Q) = l_2$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
265 |
\hspace{4mm} $\Gamma \vdash l_1 < l_2$\\\hline
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
266 |
$\Gamma \vdash slev(P) < slev(Q)$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
267 |
\end{tabular}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
268 |
\end{center}}\bigskip\pause
|
67
|
269 |
|
|
270 |
\begin{itemize}
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
271 |
\item \bl{$slev($Bob$)$ $=$ $S$}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
272 |
\item \bl{$slev($File$)$ $=$ $P$}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
273 |
\item \bl{$slev(P) < slev(S)$}
|
67
|
274 |
\end{itemize}
|
|
275 |
|
|
276 |
\end{frame}}
|
|
277 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
278 |
%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
279 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
280 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
281 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
282 |
\frametitle{Reading a File}
|
67
|
283 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
284 |
\bl{\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
285 |
\begin{tabular}{c}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
286 |
\begin{tabular}{@ {}l@ {}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
287 |
$slev($File$)$ $<$ $slev($Bob$)$ $\Rightarrow$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
288 |
\hspace{3cm}Bob controls Permitted $($File, read$)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
289 |
Bob says Permitted $($File, read$)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
290 |
$slev($File$)$ $=$ $P$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
291 |
$slev($Bob$)$ $=$ $T\!S$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
292 |
\only<1>{\textcolor{red}{$?$}}%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
293 |
\only<2>{\textcolor{red}{$slev(P) < slev(S)$}\\}%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
294 |
\only<2>{\textcolor{red}{$slev(S) < slev(T\!S)$}}%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
295 |
\end{tabular}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
296 |
\hline
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
297 |
Permitted $($File, read$)$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
298 |
\end{tabular}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
299 |
\end{center}}
|
67
|
300 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
301 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
302 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
303 |
%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
304 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
305 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
306 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
307 |
\frametitle{Transitivity Rule}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
308 |
\small
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
309 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
310 |
\bl{\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
311 |
\begin{tabular}{c}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
312 |
$\Gamma \vdash l_1 < l_2$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
313 |
\hspace{4mm} $\Gamma \vdash l_2 < l_3$\\\hline
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
314 |
$\Gamma \vdash l_1 < l_3$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
315 |
\end{tabular}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
316 |
\end{center}}\bigskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
317 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
318 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
319 |
\item \bl{$slev(P) < slev (S)$}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
320 |
\item \bl{$slev(S) < slev (T\!S)$}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
321 |
\item[] \bl{$slev(P) < slev (T\!S)$}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
322 |
\end{itemize}
|
67
|
323 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
324 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
325 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
326 |
%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
327 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
328 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
329 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
330 |
\frametitle{Reading Files}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
331 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
332 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
333 |
\item Access policy for Bob for reading
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
334 |
\end{itemize}
|
67
|
335 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
336 |
\bl{\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
337 |
\begin{tabular}{c}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
338 |
\begin{tabular}{@ {}l@ {}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
339 |
$\forall f.\;slev(f)$ \only<1>{$<$}\only<2>{\textcolor{red}{$\le$}} $slev($Bob$)$ $\Rightarrow$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
340 |
\hspace{3cm}Bob controls Permitted $(f$, read$)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
341 |
Bob says Permitted $($File, read$)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
342 |
$slev($File$)$ $=$ \only<1>{$P$}\only<2>{\textcolor{red}{$T\!S$}}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
343 |
$slev($Bob$)$ $=$ $T\!S$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
344 |
$slev(P) < slev(S)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
345 |
$slev(S) < slev(T\!S)$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
346 |
\end{tabular}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
347 |
\hline
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
348 |
Permitted $($File, read$)$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
349 |
\end{tabular}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
350 |
\end{center}}
|
68
|
351 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
352 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
353 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
354 |
%
|
68
|
355 |
|
67
|
356 |
|
|
357 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
358 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
359 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
360 |
\frametitle{Writing Files}
|
65
|
361 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
362 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
363 |
\item Access policy for Bob for {\bf writing}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
364 |
\end{itemize}
|
65
|
365 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
366 |
\bl{\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
367 |
\begin{tabular}{c}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
368 |
\begin{tabular}{@ {}l@ {}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
369 |
$\forall f.\;slev($Bob$)$ $\le$ $slev(f)$ $\Rightarrow$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
370 |
\hspace{3cm}Bob controls Permitted $(f$, write$)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
371 |
Bob says Permitted $($File, write$)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
372 |
$slev($File$)$ $=$ $T\!S$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
373 |
$slev($Bob$)$ $=$ $S$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
374 |
$slev(P) < slev(S)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
375 |
$slev(S) < slev(T\!S)$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
376 |
\end{tabular}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
377 |
\hline
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
378 |
Permitted $($File, write$)$
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
379 |
\end{tabular}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
380 |
\end{center}}
|
65
|
381 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
382 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
383 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
384 |
%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
385 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
65
|
386 |
\mode<presentation>{
|
|
387 |
\begin{frame}[c]
|
|
388 |
\frametitle{Encrypted Messages}
|
|
389 |
|
|
390 |
\begin{itemize}
|
|
391 |
\item Alice sends a message \bl{$m$}
|
|
392 |
\begin{center}
|
|
393 |
\bl{Alice says $m$}
|
|
394 |
\end{center}\medskip\pause
|
|
395 |
|
|
396 |
\item Alice sends an encrypted message \bl{$m$}\\ (with key \bl{$K$})
|
|
397 |
\begin{center}
|
|
398 |
\bl{Alice says $\{m\}_K$}
|
|
399 |
\end{center}\medskip\pause
|
|
400 |
|
|
401 |
\item Decryption of Alice's message\smallskip
|
|
402 |
\begin{center}
|
|
403 |
\bl{\mbox{\infer{\Gamma \vdash \text{Alice}\;\text{says}\;m}
|
|
404 |
{\Gamma \vdash \text{Alice}\;\text{says}\;\{m\}_K & \Gamma \vdash \text{Alice}\,\text{says}\,K}}}
|
|
405 |
\end{center}
|
|
406 |
\end{itemize}
|
|
407 |
|
|
408 |
\end{frame}}
|
|
409 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
410 |
|
|
411 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
412 |
\mode<presentation>{
|
|
413 |
\begin{frame}[c]
|
|
414 |
\frametitle{Encryption}
|
|
415 |
|
|
416 |
\begin{itemize}
|
|
417 |
\item Encryption of a message\smallskip
|
|
418 |
\begin{center}
|
|
419 |
\bl{\mbox{\infer{\Gamma \vdash \text{Alice}\;\text{says}\;\{m\}_K}
|
|
420 |
{\Gamma \vdash \text{Alice}\;\text{says}\;m & \Gamma \vdash \text{Alice}\,\text{says}\,K}}}
|
|
421 |
\end{center}
|
|
422 |
\end{itemize}
|
|
423 |
|
|
424 |
\end{frame}}
|
|
425 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
426 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
427 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
428 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
429 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
430 |
\frametitle{Trusted Third Party}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
431 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
432 |
Simple protocol for establishing a secure connection via a mutually
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
433 |
trusted 3rd party (server):
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
434 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
435 |
\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
436 |
\begin{tabular}{@ {\hspace{-7mm}}l@{\hspace{2mm}}r@ {\hspace{1mm}}l}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
437 |
Message 1 & \bl{$A \rightarrow S :$} & \bl{$A, B$}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
438 |
Message 2 & \bl{$S \rightarrow A :$} & \bl{$\{K_{AB}\}_{K_{AS}}$} and \bl{$\{\{K_{AB}\}_{K_{BS}} \}_{K_{AS}}$}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
439 |
Message 3 & \bl{$A \rightarrow B :$} & \bl{$\{K_{AB}\}_{K_{BS}} $}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
440 |
Message 4 & \bl{$A \rightarrow B :$} & \bl{$\{m\}_{K_{AB}}$}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
441 |
\end{tabular}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
442 |
\end{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
443 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
444 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
445 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
446 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
447 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
448 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
449 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
450 |
\frametitle{Sending Rule}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
451 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
452 |
\bl{\begin{center}
|
136
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
453 |
\mbox{$\infer{\Gamma \vdash Q \;\text{says}\; F}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
454 |
{\Gamma \vdash P \;\text{says}\; F & \Gamma \vdash P \;\text{sends}\; Q : F}$}
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
455 |
\end{center}}\bigskip\pause
|
65
|
456 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
457 |
\bl{$P \,\text{sends}\, Q : F \dn$}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
458 |
\hspace{6mm}\bl{$(P \,\text{says}\, F) \Rightarrow (Q \,\text{says}\, F)$}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
459 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
460 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
461 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
462 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
463 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
65
|
464 |
\mode<presentation>{
|
|
465 |
\begin{frame}[c]
|
|
466 |
\frametitle{Trusted Third Party}
|
|
467 |
|
|
468 |
\begin{center}
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
469 |
\bl{\begin{tabular}{l}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
470 |
$A$ sends $S$ : $\text{Connect}(A,B)$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
471 |
\bl{$S \,\text{says}\, (\text{Connect}(A,B) \Rightarrow$}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
472 |
\hspace{2.5cm}\bl{$\{K_{AB}\}_{K_{AS}} \wedge
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
473 |
\{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}})$}\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
474 |
$S$ sends $A$ : $\{K_{AB}\}_{K_{AS}}$ \bl{$\wedge$} $\{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}}$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
475 |
$A$ sends $B$ : $\{K_{AB}\}_{K_{BS}}$\\
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
476 |
$A$ sends $B$ : $\{m\}_{K_{AB}}$
|
65
|
477 |
\end{tabular}}
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
478 |
\end{center}\bigskip\pause
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
479 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
480 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
481 |
\bl{$\Gamma \vdash B \,\text{says} \, m$}?
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
482 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
483 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
484 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
485 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
486 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
487 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
488 |
\frametitle{Public/Private Keys}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
489 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
490 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
491 |
\item Bob has a private and public key: \bl{$K_{Bob}^{pub}$}, \bl{$K_{Bob}^{priv}$}\bigskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
492 |
\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
493 |
\bl{\mbox{\infer{\Gamma \vdash \text{Alice}\;\text{says}\;m}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
494 |
{\Gamma \vdash \text{Alice}\;\text{says}\;\{m\}_{K_{Bob}^{pub}} &
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
495 |
\Gamma \vdash K_{Bob}^{priv}}}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
496 |
\end{center}\bigskip\pause
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
497 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
498 |
\item this is {\bf not} a derived rule!
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
499 |
\end{itemize}
|
65
|
500 |
|
|
501 |
\end{frame}}
|
|
502 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
503 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
504 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
505 |
% \begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
506 |
% \item Alice calls Sam for a key to communicate with Bob
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
507 |
% \item Sam responds with a key that Alice can read and a key Bob can read (pre-shared)
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
508 |
% \item Alice sends the message encrypted with the key and the second key it recieved
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
509 |
% \end{itemize}\bigskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
510 |
|
65
|
511 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
512 |
\mode<presentation>{
|
|
513 |
\begin{frame}[c]
|
|
514 |
\frametitle{Sending Rule}
|
|
515 |
|
70
|
516 |
|
65
|
517 |
\bl{\begin{center}
|
|
518 |
\mbox{\infer{\Gamma \vdash Q \;\textit{says}\; F}
|
|
519 |
{\Gamma \vdash P \;\textit{says}\; F & \Gamma \vdash P \;\textit{sends}\; Q : F}}
|
|
520 |
\end{center}}\bigskip\pause
|
|
521 |
|
|
522 |
\bl{$P \,\text{sends}\, Q : F \dn$}\\
|
|
523 |
\hspace{6mm}\bl{$(P \,\text{says}\, F) \Rightarrow (Q \,\text{says}\, F)$}
|
|
524 |
|
|
525 |
\end{frame}}
|
|
526 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
527 |
|
|
528 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
529 |
\mode<presentation>{
|
|
530 |
\begin{frame}[c]
|
|
531 |
\frametitle{Trusted Third Party}
|
|
532 |
|
|
533 |
\begin{center}
|
|
534 |
\bl{\begin{tabular}{l}
|
|
535 |
$A$ sends $S$ : $\textit{Connect}(A,B)$\\
|
|
536 |
\bl{$S \,\text{says}\, (\textit{Connect}(A,B) \Rightarrow$}\\
|
|
537 |
\hspace{2.5cm}\bl{$\{K_{AB}\}_{K_{AS}} \wedge
|
|
538 |
\{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}})$}\\
|
|
539 |
$S$ sends $A$ : $\{K_{AB}\}_{K_{AS}}$ \bl{$\wedge$} $\{\{K_{AB}\}_{K_{BS}}\}_{K_{AS}}$\\
|
|
540 |
$A$ sends $B$ : $\{K_{AB}\}_{K_{BS}}$\\
|
|
541 |
$A$ sends $B$ : $\{m\}_{K_{AB}}$
|
|
542 |
\end{tabular}}
|
|
543 |
\end{center}\bigskip\pause
|
|
544 |
|
|
545 |
|
|
546 |
\bl{$\Gamma \vdash B \,\text{says} \, m$}?
|
|
547 |
\end{frame}}
|
|
548 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
549 |
|
|
550 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
551 |
\mode<presentation>{
|
|
552 |
\begin{frame}[c]
|
|
553 |
\frametitle{Challenge-Response Protocol}
|
|
554 |
|
|
555 |
\begin{itemize}
|
|
556 |
\item an engine \bl{$E$} and a transponder \bl{$T$} share a key \bl{$K$}\bigskip
|
|
557 |
\item \bl{$E$} sends out a \alert{nonce} \bl{$N$} (random number) to \bl{$T$}\bigskip
|
|
558 |
\item \bl{$T$} responds with \bl{$\{N\}_K$}\bigskip
|
68
|
559 |
\item if \bl{$E$} receives \bl{$\{N\}_K$} from \bl{$T$}, it starts engine
|
65
|
560 |
\end{itemize}
|
|
561 |
|
|
562 |
\end{frame}}
|
|
563 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
564 |
|
|
565 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
566 |
\mode<presentation>{
|
|
567 |
\begin{frame}[c]
|
68
|
568 |
\frametitle{Challenge-Response Protocol}
|
65
|
569 |
|
|
570 |
\begin{center}
|
|
571 |
\bl{\begin{tabular}{l}
|
|
572 |
$E \;\text{says}\; N$\hfill(start)\\
|
|
573 |
$E \;\text{sends}\; T : N$\hfill(challenge)\\
|
|
574 |
$(T \;\text{says}\; N) \Rightarrow (T \;\text{sends}\; E : \{N\}_K \wedge$\\
|
|
575 |
\hspace{3.5cm} $T \;\text{sends}\; E : \text{Id}(T))$\;\;\;\hfill(response)\\
|
|
576 |
$T \;\text{says}\; K$\hfill(key)\\
|
|
577 |
$T \;\text{says}\; \text{Id}(T)$\hfill(identity)\\
|
|
578 |
$(E \;\text{says}\; \{N\}_K \wedge E \;\text{says}\; \text{Id}(T)) \Rightarrow$\\
|
|
579 |
\hspace{5cm}$ \text{start\_engine}(T)$\hfill(engine)\\
|
|
580 |
\end{tabular}}
|
|
581 |
\end{center}\bigskip
|
|
582 |
|
|
583 |
\bl{$\Gamma \vdash \text{start\_engine}(T)$}?
|
|
584 |
\end{frame}}
|
|
585 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
586 |
|
68
|
587 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
588 |
\mode<presentation>{
|
|
589 |
\begin{frame}[c]
|
|
590 |
\frametitle{Exchange of a Fresh Key}
|
|
591 |
|
70
|
592 |
\bl{$A$} and \bl{$B$} share a (``super-secret'') key \bl{$K_{AB}$} and want to share another key
|
69
|
593 |
|
68
|
594 |
\begin{itemize}
|
|
595 |
\item assumption \bl{$K_{AB}$} is only known to \bl{$A$} and \bl{$B$}\bigskip
|
|
596 |
\item \bl{$A \,\text{sends}\, B : A, \{N_A\}_{K_{AB}}$}
|
|
597 |
\item \bl{$B\,\text{sends}\, A : \{N_A + 1, N_B\}_{K_{AB}}$}
|
|
598 |
\item \bl{$A \,\text{sends}\, B : \{N_B + 1\}_{K_{AB}}$}
|
|
599 |
\item \bl{$B \,\text{sends}\, A : \{K^{new}_{AB}, N^{new}_B\}_{K_{AB}}$}
|
69
|
600 |
\item<2> \bl{$A \,\text{sends}\, B : \{msg\}_{K^{new}_{AB}}$}
|
|
601 |
\end{itemize}\bigskip
|
68
|
602 |
|
69
|
603 |
Assume \bl{$K^{new}_{AB}$} is compromised by \bl{$I$}
|
68
|
604 |
\end{frame}}
|
|
605 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
606 |
|
|
607 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
608 |
\mode<presentation>{
|
|
609 |
\begin{frame}[c]
|
|
610 |
\frametitle{The Attack}
|
|
611 |
|
69
|
612 |
An intruder \bl{$I$} convinces \bl{$A$} to accept the compromised key \bl{$K^{new}_{AB}$}\medskip
|
68
|
613 |
|
69
|
614 |
\begin{minipage}{1.1\textwidth}
|
68
|
615 |
\begin{itemize}
|
|
616 |
\item \bl{$A \,\text{sends}\, B : A, \{N_A\}_{K_{AB}}$}
|
|
617 |
\item \bl{$B\,\text{sends}\, A : \{N_A + 1, N_B\}_{K_{AB}}$}
|
|
618 |
\item \bl{$A \,\text{sends}\, B : \{N_B + 1\}_{K_{AB}}$}
|
69
|
619 |
\item \bl{$B \,\text{sends}\, A : \{K^{new}_{AB}, N^{new}_B\}_{K_{AB}}$}\;\;recorded by \bl{$I$}\pause
|
|
620 |
\item \bl{$A \,\text{sends}\, B : A, \{M_A\}_{K_{AB}}$}
|
|
621 |
\item \bl{$B\,\text{sends}\, A : \{M_A + 1, M_B\}_{K_{AB}}$}
|
|
622 |
\item \bl{$A \,\text{sends}\, B : \{M_B + 1\}_{K_{AB}}$}
|
70
|
623 |
\item \bl{$B \,\text{sends}\, I : \{K^{newer}_{AB}, N^{newer}_B\}_{K_{AB}}$}\;intercepted by \bl{$I$}
|
69
|
624 |
\item \bl{$I \,\text{sends}\, A : \{K^{new}_{AB}, N^{new}_B\}_{K_{AB}}$}\pause
|
70
|
625 |
\item \bl{$A \,\text{sends}\, B : \{msg\}_{K^{new}_{AB}}$}\;\;\;\;\bl{$I$} can read it also
|
68
|
626 |
\end{itemize}
|
69
|
627 |
\end{minipage}
|
68
|
628 |
|
|
629 |
\end{frame}}
|
|
630 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
631 |
|
70
|
632 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
633 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
634 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
635 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
636 |
A Man-in-the-middle attack in real life:
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
637 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
638 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
639 |
\item the card only says yes or no to the terminal if the PIN is correct
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
640 |
\item trick the card in thinking transaction is verified by signature
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
641 |
\item trick the terminal in thinking the transaction was verified by PIN
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
642 |
\end{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
643 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
644 |
\begin{minipage}{1.1\textwidth}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
645 |
\begin{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
646 |
\mbox{}\hspace{-6mm}\includegraphics[scale=0.5]{pics/chip-attack.png}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
647 |
\includegraphics[scale=0.3]{pics/chipnpinflaw.png}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
648 |
\end{center}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
649 |
\end{minipage}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
650 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
651 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
652 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
653 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
654 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
655 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
656 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
657 |
\frametitle{Problems with EMV}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
658 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
659 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
660 |
\item it is a wrapper for many protocols
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
661 |
\item specification by consensus (resulted unmanageable complexity)
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
662 |
\item its specification is 700 pages in English plus 2000+ pages for testing, additionally some
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
663 |
further parts are secret
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
664 |
\item other attacks have been found
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
665 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
666 |
\item one solution might be to require always online verification of the PIN with the bank
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
667 |
\end{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
668 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
669 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
670 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
671 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
672 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
673 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
674 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
675 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
676 |
\frametitle{\begin{tabular}{c}Problems with WEP (Wifi)\end{tabular}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
677 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
678 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
679 |
\item a standard ratified in 1999
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
680 |
\item the protocol was designed by a committee not including cryptographers
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
681 |
\item it used the RC4 encryption algorithm which is a stream cipher requiring a unique nonce
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
682 |
\item WEP did not allocate enough bits for the nonce
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
683 |
\item for authenticating packets it used CRC checksum which can be easily broken
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
684 |
\item the network password was used to directly encrypt packages (instead of a key negotiation protocol)\bigskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
685 |
\item encryption was turned off by default
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
686 |
\end{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
687 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
688 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
689 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
690 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
691 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
692 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
693 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
694 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
695 |
\frametitle{Protocols are Difficult}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
696 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
697 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
698 |
\item even the systems designed by experts regularly fail\medskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
699 |
\item try to make everything explicit (you need to authenticate all data you might rely on)\medskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
700 |
\item the one who can fix a system should also be liable for the losses\medskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
701 |
\item cryptography is often not {\bf the} answer\bigskip\bigskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
702 |
\end{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
703 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
704 |
logic is one way protocols are studied in academia
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
705 |
(you can use computers to search for attacks)
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
706 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
707 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
708 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
709 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
710 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
711 |
\mode<presentation>{
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
712 |
\begin{frame}[c]
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
713 |
\frametitle{Public-Key Infrastructure}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
714 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
715 |
\begin{itemize}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
716 |
\item the idea is to have a certificate authority (CA)
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
717 |
\item you go to the CA to identify yourself
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
718 |
\item CA: ``I, the CA, have verified that public key \bl{$P^{pub}_{Bob}$} belongs to Bob''\bigskip
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
719 |
\item CA must be trusted by everybody
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
720 |
\item What happens if CA issues a false certificate? Who pays in case of loss? (VeriSign
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
721 |
explicitly limits liability to \$100.)
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
722 |
\end{itemize}
|
70
|
723 |
|
135
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
724 |
\end{frame}}
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
725 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
726 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
727 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
728 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
729 |
|
Christian Urban <christian dot urban at kcl dot ac dot uk>
diff
changeset
|
730 |
|
70
|
731 |
|
|
732 |
|
65
|
733 |
\end{document}
|
|
734 |
|
|
735 |
%%% Local Variables:
|
|
736 |
%%% mode: latex
|
|
737 |
%%% TeX-master: t
|
|
738 |
%%% End:
|
|
739 |
|