\documentclass[dvipsnames,14pt,t]{beamer}\usepackage{../slides}\usepackage{../langs}\usepackage{../graphics}\usepackage{../data}\usepackage{../grammar}% beamer stuff \renewcommand{\slidecaption}{SEN 11, King's College London}\newcommand{\bl}[1]{\textcolor{blue}{#1}}\begin{document}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\begin{frame}[t]\frametitle{% \begin{tabular}{@ {}c@ {}} \\ \LARGE Access Control and \\[-3mm] \LARGE Privacy Policies (11)\\[-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}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\begin{frame}[c]\begin{itemize}\item you can still send me your homework\bigskip \item Unix AC question: use a terminal-based editor (vm, vim)\bigskip \item exams: 2 out of 3 questions, 5 or so subquestions each, you can fill in your answers on the question sheet\end{itemize}\end{frame}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\begin{frame}[c]\frametitle{Interlock Protocol}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 theweather today in London?\end{frame}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\begin{frame}[c]\begin{center}\begin{tabular}{l@{\hspace{9mm}}l}\begin{tabular}[t]{@{}l@{}}\bl{$A \to C : K^{pub}_A$}\\\bl{$C \to B : K^{pub}_C$}\\\bl{$B \to C : K^{pub}_B$}\\\bl{$C \to A : K^{pub}_C$}\medskip\\\bl{$\{A,m\}_{K^{pub}_C} \;\mapsto\; H_1,H_2$}\\\bl{$\{B,n\}_{K^{pub}_C} \;\mapsto\; M_1,M_2$}\bigskip\\\bl{$\{C,a\}_{K^{pub}_B} \;\mapsto\; C_1,C_2$}\\\bl{$\{C,b\}_{K^{pub}_A} \;\mapsto\; D_1,D_2$}\end{tabular} &\begin{tabular}[t]{@{}l@{}}\bl{$A \to C : H_1$}\\\bl{$C \to B : C_1$}\\\bl{$B \to C : \{C_1, M_1\}_{K^{pub}_C}$}\\\bl{$C \to A : \{H_1, D_1\}_{K^{pub}_A}$}\\\bl{$A \to C : \{H_2, D_1\}_{K^{pub}_C}$}\\\bl{$C \to B : \{C_2, M_1\}_{K^{pub}_B}$}\\\bl{$B \to C : M_2$}\\\bl{$C \to A : D_2$}\end{tabular}\end{tabular}\end{center}\end{frame}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\begin{frame}[c]\begin{itemize}\item you have to ask something that cannot imitated (requires \bl{$A$} and \bl{$B$} know each other)\item what happens if \bl{$m$} and \bl{$n$} are voice messages?\bigskip \item the moral: establishing a secure connection from ``zero'' isalmost impossible---you need to rely on some established trust\medskip\item that is why we rely on certificates, which however arebadly, badly realised (just today a POODLE attack against SSL)\end{itemize}\end{frame}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \end{document}%%% Local Variables: %%% mode: latex%%% TeX-master: t%%% End: