slides/slides05.tex
author cu
Mon, 23 Oct 2017 00:50:09 +0100
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\PassOptionsToPackage{bookmarks=false}{hyperref}
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\documentclass[dvipsnames,14pt,t,hyperref={bookmarks=false}]{beamer}
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\usepackage{../style}
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\usepackage{../slides}
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\usepackage{../graphics}
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\usepackage{../langs}
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\usepackage{../data}
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\usetikzlibrary{arrows}
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\usetikzlibrary{shapes}
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\setmonofont[Scale=.88]{Consolas}
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\newfontfamily{\consolas}{Consolas}
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\hfuzz=220pt 
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% beamer stuff 
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\newcommand{\bl}[1]{\textcolor{blue}{#1}}  
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\renewcommand{\slidecaption}{SEN 05, King's College London}
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\begin{document}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\begin{frame}[t]
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\frametitle{%
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  \begin{tabular}{@ {}c@ {}}
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  \\
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  \LARGE Security Engineering (5)\\[-3mm] 
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  \end{tabular}}\bigskip\bigskip\bigskip
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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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  Office: & N7.07 (North Wing, Bush House)\\
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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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\begin{frame}[c]
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\frametitle{Protocols}
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\begin{center}
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\includegraphics[scale=0.11]{../pics/keyfob.jpg}
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\quad
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\includegraphics[scale=0.3025]{../pics/startstop.jpg}
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\end{center}
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\begin{itemize}
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\item Other examples: Wifi, Http-request, TCP-request,
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card readers, RFID (passports)\ldots\medskip\pause
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\item The point is that we cannot control the network: An attacker
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can install a packet sniffer, inject packets, modify packets,
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replay messages\ldots{}fake pretty much everything.
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\end{itemize}
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\begin{frame}[c]
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\frametitle{Keyless Car Transponders}
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\begin{center}
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\includegraphics[scale=0.1]{../pics/keyfob.jpg}
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\quad
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\includegraphics[scale=0.27]{../pics/startstop.jpg}
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\end{center}
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\begin{itemize}
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\item There are two security mechanisms: one remote central 
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locking system and one passive RFID tag (engine immobiliser).
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\item How can I get in? How can thieves be kept out? 
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How to avoid MITM attacks?
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\end{itemize}\medskip
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\footnotesize
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\hfill Papers: Gone in 360 Seconds: Hijacking with Hitag2,\\
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\hfill Dismantling Megamos Crypto: Wirelessly Lockpicking\\
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\hfill a Vehicle Immobilizer
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\begin{frame}[c]
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\frametitle{Problems with Key Fobs}
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\begin{columns}
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\begin{column}[T]{4cm}
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\includegraphics[scale=0.4]{../pics/car-standard.jpg}
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\end{column}
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\begin{column}[T]{6cm}\small 
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Circumventing the ignition protection:
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\begin{itemize}
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\item either dismantling Megamos crypto,
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\item or use the diagnostic port to program 
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  blank keys 
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\end{itemize}
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\hspace{14mm}
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\includegraphics[scale=0.16]{../pics/Dismantling_Megamos_Crypto.png}
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\end{column}
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\end{columns}
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\begin{frame}[c]
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\frametitle{HTTPS / GSM}
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\begin{center}
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\includegraphics[scale=0.25]{../pics/barclays.jpg}
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\quad
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\includegraphics[scale=0.25]{../pics/phone-signal.jpg}
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\end{center}
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\begin{itemize}
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\item I am sitting at Starbuck. How can I be sure I am really
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      visiting Barclays? I have no control of the access
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      point.
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\item How can I achieve that a secret key is established in
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      order to encrypt my mobile conversation? I have no
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      control over the access points. 
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\end{itemize}
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\end{frame}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\begin{frame}[c]
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\frametitle{G20 Summit in 2009}
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\begin{center}
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\includegraphics[scale=0.1]{../pics/snowden.jpg}
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\end{center}
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\small
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\begin{itemize}
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\item Snowden documents reveal ``that during the G20
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      meetings\dots{}GCHQ used 
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      `ground-breaking intelligence capabilities' to intercept
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      the communications of visiting delegations. This
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      included setting up internet cafes where they used an
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      email interception program and key-logging software to
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      spy on delegates' use of computers\ldots''
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   156
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Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   157
\item ``The G20 spying appears to have been organised for the
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   158
      more mundane purpose of securing an advantage in
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   159
      meetings.'' 
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   160
\end{itemize}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   161
  
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   162
\end{frame}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   163
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   164
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   165
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   166
\begin{frame}[c]
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   167
\frametitle{Handshakes}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   168
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   169
\begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   170
\item starting a TCP connection between a client and a server
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   171
initiates the following three-way handshake protocol:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   172
\end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   173
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   174
\begin{columns}[t]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   175
\begin{column}{5cm}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   176
\begin{minipage}[t]{4cm}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   177
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   178
\raisebox{-2cm}{\includegraphics[scale=0.5]{../pics/handshake.png}}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   179
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   180
\end{minipage}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   181
\end{column}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   182
\begin{column}{5cm}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   183
\begin{tabular}[t]{rl}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   184
Alice:  & Hello server!\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   185
Server: & I heard you\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   186
Alice:  & Thanks
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   187
\end{tabular}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   188
\end{column}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   189
\end{columns}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   190
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   191
\only<2>{
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   192
\begin{textblock}{3}(11,5)
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   193
\begin{bubble}[3.2cm]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   194
SYNflood attacks:\medskip\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   195
\includegraphics[scale=0.4]{../pics/synflood.png}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   196
\end{bubble}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   197
\end{textblock}}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   198
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   199
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   200
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   201
   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   202
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
484
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   203
\begin{frame}[t]
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   204
\frametitle{Protocols}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   205
 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   206
\mbox{} 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   207
  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   208
\begin{tabular}{l}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   209
{\Large \bl{$A\;\rightarrow\; B : \ldots$}}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   210
\onslide<2->{\Large \bl{$B\;\rightarrow\; A : \ldots$}}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   211
\onslide<2->{\Large \;\;\;\;\;\bl{$:$}}\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   212
\end{tabular}  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   213
  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   214
 \begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   215
 \item by convention \bl{$A$}, \bl{$B$} are named principals \bl{Alice\ldots}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   216
 but most likely they are programs, which just follow some instructions (they are more like roles)\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   217
\item<2-> indicates one ``protocol run'', or session,  which specifies some 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   218
order in the communication
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   219
\item<2-> there can be several sessions in parallel (think of wifi routers) 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   220
\end{itemize} 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   221
  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   222
  \end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   223
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
484
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   224
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   225
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   226
\begin{frame}[t]
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   227
\frametitle{Messages}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   228
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   229
\mbox{}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   230
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   231
\begin{tabular}{l}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   232
{\Large \bl{$A\;\rightarrow\; B : msg$}}\\
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   233
\end{tabular}\bigskip  
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   234
  
484
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   235
\begin{itemize}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   236
\item Unencrypted: \bl{$msg$}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   237
\item Random number (nonce): \bl{$N$}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   238
\item Encrypted: \bl{$\{msg\}_K$}, \bl{$\{msg_1, msg_2\}_K$}, \bl{$\{\{msg\}_{K_1}\}_{K_2}$}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   239
\end{itemize} 
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   240
  
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   241
  \end{frame}
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   242
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   243
ddcc4ef4f82c updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 483
diff changeset
   244
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   245
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   246
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   247
\frametitle{Handshakes}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   248
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   249
\begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   250
\item starting a TCP connection between a client and a server
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   251
initiates the following three-way handshake protocol:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   252
\end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   253
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   254
\begin{columns}[t]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   255
\begin{column}{5cm}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   256
\begin{minipage}[t]{4cm}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   257
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   258
\raisebox{-2cm}{\includegraphics[scale=0.5]{../pics/handshake.png}}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   259
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   260
\end{minipage}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   261
\end{column}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   262
\begin{column}{5cm}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   263
\begin{tabular}[t]{rl}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   264
Alice:  & Hello server!\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   265
Server: & I heard you\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   266
Alice:  & Thanks
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   267
\end{tabular}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   268
\end{column}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   269
\end{columns}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   270
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   271
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   272
\begin{tabular}{rl}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   273
\bl{$A \rightarrow S$}: & \bl{SYN}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   274
\bl{$S \rightarrow A$}: & \bl{SYN-ACK}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   275
\bl{$A \rightarrow S$}: & \bl{ACK}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   276
\end{tabular}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   277
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   278
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   279
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   280
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   281
  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   282
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   283
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   284
\frametitle{\Large Cryptographic Protocol Failures}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   285
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   286
Ross Anderson and Roger Needham wrote:\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   287
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   288
\begin{quote}\rm
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   289
A lot of the recorded frauds were the result of this kind of
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   290
  blunder, or from management negligence pure and simple. 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   291
  \alert{However,
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   292
there have been a significant number of cases where the designers
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   293
protected the right things, used cryptographic algorithms which were
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   294
not broken, and yet found that their systems were still successfully
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   295
attacked.}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   296
\end{quote}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   297
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   298
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   299
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   300
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   301
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   302
  \begin{frame}<1-3>[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   303
  \frametitle{Oyster Cards}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   304
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   305
  \includegraphics[scale=0.4]{../pics/oysterc.jpg}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   306
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   307
  \begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   308
  \item good example of a bad protocol\\ (security by obscurity)\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   309
  \item<3->  {\it``Breaching security on Oyster cards should not 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   310
  allow unauthorised use for more than a day, as TfL promises to turn 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   311
  off any cloned cards within 24 hours\ldots''}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   312
  \end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   313
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   314
  \only<2>{
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   315
  \begin{textblock}{12}(0.5,0.5)
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   316
  \begin{bubble}[11cm]\footnotesize
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   317
  {\bf Wirelessly Pickpocketing a Mifare Classic Card}\medskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   318
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   319
  The Mifare Classic is the most widely used contactless smartcard on the
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   320
  market. The stream cipher CRYPTO1 used by the Classic has recently been
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   321
  reverse engineered and serious attacks have been proposed. The most serious
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   322
  of them retrieves a secret key in under a second. In order to clone a card,
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   323
  previously proposed attacks require that the adversary either has access to
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   324
  an eavesdropped communication session or executes a message-by-message
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   325
  man-in-the-middle attack between the victim and a legitimate
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   326
  reader. Although this is already disastrous from a cryptographic point of
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   327
  view, system integrators maintain that these attacks cannot be performed
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   328
  undetected.\smallskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   329
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   330
  This paper proposes four attacks that can be executed by an adversary having
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   331
  only wireless access to just a card (and not to a legitimate reader). The
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   332
  most serious of them recovers a secret key in less than a second on ordinary
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   333
  hardware. Besides the cryptographic weaknesses, we exploit other weaknesses
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   334
  in the protocol stack. A vulnerability in the computation of parity bits
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   335
  allows an adversary to establish a side channel. Another vulnerability
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   336
  regarding nested authentications provides enough plaintext for a speedy
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   337
  known-plaintext attack.\hfill{}(a paper from 2009)
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   338
  \end{bubble}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   339
  \end{textblock}}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   340
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   341
  \end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   342
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   343
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   344
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   345
\begin{frame}<1->[t]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   346
\frametitle{Another Example}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   347
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   348
In an email from Ross Anderson\bigskip\small	
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   349
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   350
\begin{tabular}{l}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   351
From: Ross Anderson <Ross.Anderson@cl.cam.ac.uk>\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   352
Sender: cl-security-research-bounces@lists.cam.ac.uk\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   353
To: cl-security-research@lists.cam.ac.uk\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   354
Subject: Birmingham case\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   355
Date: Tue, 13 Aug 2013 15:13:17 +0100\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   356
\end{tabular}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   357
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   358
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   359
\only<2>{
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   360
\begin{textblock}{12}(0.5,0.8)
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   361
\begin{bubble}[11cm]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   362
\footnotesize
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   363
As you may know, Volkswagen got an injunction against the University of
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   364
Birmingham suppressing the publication of the design of a weak cipher
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   365
used in the remote key entry systems in its recent-model cars. The paper
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   366
is being given today at Usenix, minus the cipher design.\medskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   367
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   368
I've been contacted by Birmingham University's lawyers who seek to prove
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   369
that the cipher can be easily obtained anyway. They are looking for a
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   370
student who will download the firmware from any newish VW, disassemble
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   371
it and look for the cipher. They'd prefer this to be done by a student
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   372
rather than by a professor to emphasise how easy it is.\medskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   373
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   374
Volkswagen's argument was that the Birmingham people had reversed a
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   375
locksmithing tool produced by a company in Vietnam, and since their key
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   376
fob chip is claimed to be tamper-resistant, this must have involved a
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   377
corrupt insider at VW or at its supplier Thales. Birmingham's argument
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   378
is that this is nonsense as the cipher is easy to get hold of. Their
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   379
lawyers feel this argument would come better from an independent
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   380
outsider.\medskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   381
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   382
Let me know if you're interested in having a go, and I'll put you in
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   383
touch
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   384
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   385
Ross
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   386
\end{bubble}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   387
\end{textblock}}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   388
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   389
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   390
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   391
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   392
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   393
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   394
\frametitle{Authentication Protocols}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   395
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   396
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   397
Alice (\bl{$A$}) and Bob (\bl{$B$}) share a secret key \bl{$K_{AB}$}\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   398
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   399
Passwords:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   400
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   401
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   402
\bl{$B \rightarrow A: K_{AB}$} 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   403
\end{center}\pause\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   404
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   405
Problem: Eavesdropper can capture the secret and replay it; \bl{$A$} cannot confirm the
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   406
identity of \bl{$B$}  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   407
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   408
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   409
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   410
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   411
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   412
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   413
\frametitle{Authentication?}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   414
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   415
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   416
\raisebox{-2cm}{\includegraphics[scale=0.4]{../pics/dogs.jpg}}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   417
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   418
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   419
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   420
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   421
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   422
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   423
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   424
\frametitle{Authentication Protocols}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   425
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   426
Alice (\bl{$A$}) and Bob (\bl{$B$}) share a secret key \bl{$K_{AB}$}\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   427
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   428
Simple Challenge Response:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   429
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   430
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   431
\begin{tabular}{ll}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   432
\bl{$A \rightarrow B:$} & \bl{$N$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   433
\bl{$B \rightarrow A:$} & \bl{$\{N\}_{K_{AB}}$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   434
\end{tabular} 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   435
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   436
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   437
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   438
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   439
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   440
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   441
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   442
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   443
\frametitle{Authentication Protocols}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   444
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   445
Alice (\bl{$A$}) and Bob (\bl{$B$}) share a secret key \bl{$K_{AB}$}\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   446
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   447
Mutual Challenge Response:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   448
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   449
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   450
\begin{tabular}{ll}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   451
\bl{$A \rightarrow B:$} & \bl{$N_A$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   452
\bl{$B \rightarrow A:$} & \bl{$\{N_A, N_B\}_{K_{AB}}$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   453
\bl{$A \rightarrow B:$} & \bl{$N_B$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   454
\end{tabular} 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   455
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   456
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   457
%\pause
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   458
%An attacker \bl{$E$} can launch an impersonation attack by
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   459
%intercepting all messages for \bl{$B$} and make \bl{$A$} decrypt her
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   460
%own challenges.
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   461
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   462
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   463
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   464
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   465
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   466
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   467
\frametitle{Nonces}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   468
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   469
\begin{enumerate}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   470
\item I generate a nonce (random number) and send it to you encrypted with a key we share
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   471
\item you increase it by one, encrypt it under a key I know and send
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   472
it back to me
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   473
\end{enumerate}\medskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   474
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   475
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   476
I can infer:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   477
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   478
\begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   479
\item you must have received my message
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   480
\item you could only have generated your answer after I send you my initial
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   481
message
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   482
\item if only you and me know the key, the message must have come from you
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   483
\end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   484
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   485
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   486
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   487
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   488
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   489
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   490
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   491
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   492
\begin{tabular}{ll}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   493
\bl{$A \rightarrow B$:} & \bl{$N_A$}\\  
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   494
\bl{$B \rightarrow A$:} & \bl{$\{N_A, N_B\}_{K_{AB}}$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   495
\bl{$A \rightarrow B$:} & \bl{$N_B$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   496
\end{tabular}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   497
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   498
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   499
The attack (let $A$ decrypt her own messages):
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   500
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   501
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   502
\begin{tabular}{ll}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   503
\bl{$A \rightarrow E$:} & \bl{$N_A$}\\ 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   504
\textcolor{gray}{$E \rightarrow A$:} & \textcolor{gray}{$N_A$}\\ 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   505
\textcolor{gray}{$A \rightarrow E$:} & \textcolor{gray}{$\{N_A, N_A'\}_{K_{AB}}$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   506
\bl{$E \rightarrow A$:} & \bl{$\{N_A, N_A'\}_{K_{AB}}$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   507
\bl{$A \rightarrow E$:} & \bl{$N_A' \;\;(= N_B)$}\\
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   508
\end{tabular}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   509
\end{center}\pause
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   510
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   511
\small Solutions: \bl{$K_{AB} \not= K_{BA}$} or include an id in the second message
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   512
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   513
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   514
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   515
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   516
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   517
\frametitle{Encryption to the Rescue?}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   518
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   519
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   520
 \begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   521
 \item \bl{$A \,\rightarrow\, B :  \{A, N_A\}_{K_{AB}}$}\hspace{1cm} encrypted\bigskip 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   522
 \item \bl{$B\,\rightarrow\, A : \{N_A, K'_{AB}\}_{K_{AB}}$}\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   523
 \item \bl{$A \,\rightarrow\, B : \{N_A\}_{K'_{AB}}$}\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   524
 \end{itemize}\pause
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   525
 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   526
means you need to send separate ``Hello'' signals (bad), or worse 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   527
share a single key between many entities
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   528
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   529
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%      
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   530
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   531
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
555
f99817977494 updated
cu
parents: 518
diff changeset
   532
% \begin{frame}[c]
f99817977494 updated
cu
parents: 518
diff changeset
   533
% \frametitle{Protocol Attacks}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   534
555
f99817977494 updated
cu
parents: 518
diff changeset
   535
% \begin{itemize}
f99817977494 updated
cu
parents: 518
diff changeset
   536
% \item replay attacks
f99817977494 updated
cu
parents: 518
diff changeset
   537
% \item reflection attacks
f99817977494 updated
cu
parents: 518
diff changeset
   538
% \item man-in-the-middle attacks
f99817977494 updated
cu
parents: 518
diff changeset
   539
% \item timing attacks
f99817977494 updated
cu
parents: 518
diff changeset
   540
% \item parallel session attacks
f99817977494 updated
cu
parents: 518
diff changeset
   541
% \item binding attacks (public key protocols)
f99817977494 updated
cu
parents: 518
diff changeset
   542
% \item changing environment / changing assumptions\bigskip
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   543
555
f99817977494 updated
cu
parents: 518
diff changeset
   544
% \item (social engineering attacks)
f99817977494 updated
cu
parents: 518
diff changeset
   545
% \end{itemize}
f99817977494 updated
cu
parents: 518
diff changeset
   546
% \end{frame}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   547
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   548
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   549
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   550
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   551
\frametitle{Public-Key Infrastructure}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   552
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   553
\begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   554
\item the idea is to have a certificate authority (CA)
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   555
\item you go to the CA to identify yourself
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   556
\item CA: ``I, the CA, have verified that public key \bl{$P^{pub}_{Bob}$} belongs to Bob''\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   557
\item CA must be trusted by everybody
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   558
\item What happens if CA issues a false certificate? Who pays in case of loss? (VeriSign 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   559
explicitly limits liability to \$100.)
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   560
\end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   561
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   562
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   563
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   564
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   565
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   566
\begin{frame}[c]
555
f99817977494 updated
cu
parents: 518
diff changeset
   567
\frametitle{A Simple PK Protocol}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   568
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   569
``Normal'' protocol run:\bigskip
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   570
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   571
\begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   572
\item \bl{$A$} sends public key  to \bl{$B$}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   573
\item \bl{$B$} sends public key  to \bl{$A$}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   574
\item \bl{$A$} sends message encrypted with \bl{$B$}'s public key, \bl{$B$} decrypts it
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   575
with its private key
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   576
\item \bl{$B$} sends message encrypted with \bl{$A$}'s public key, \bl{$A$} decrypts it
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   577
with its private key
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   578
\end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   579
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   580
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   581
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   582
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   583
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   584
\begin{frame}[c]
555
f99817977494 updated
cu
parents: 518
diff changeset
   585
\frametitle{A Simple PK Protocol}
f99817977494 updated
cu
parents: 518
diff changeset
   586
f99817977494 updated
cu
parents: 518
diff changeset
   587
f99817977494 updated
cu
parents: 518
diff changeset
   588
\begin{center}
f99817977494 updated
cu
parents: 518
diff changeset
   589
\begin{tabular}{ll@{\hspace{2mm}}l}
f99817977494 updated
cu
parents: 518
diff changeset
   590
1. & \bl{$A \to B :$} & \bl{$K^{pub}_A$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   591
2. & \bl{$B \to A :$} & \bl{$K^{pub}_B$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   592
3. & \bl{$A \to B :$} & \bl{$\{A,m\}_{K^{pub}_B}$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   593
4. & \bl{$B \to A :$} & \bl{$\{B,m'\}_{K^{pub}_A}$}
f99817977494 updated
cu
parents: 518
diff changeset
   594
\end{tabular}
f99817977494 updated
cu
parents: 518
diff changeset
   595
\end{center}\pause\bigskip
f99817977494 updated
cu
parents: 518
diff changeset
   596
f99817977494 updated
cu
parents: 518
diff changeset
   597
unfortunately there is a simple man-in-the- middle-attack
f99817977494 updated
cu
parents: 518
diff changeset
   598
\end{frame}
f99817977494 updated
cu
parents: 518
diff changeset
   599
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
f99817977494 updated
cu
parents: 518
diff changeset
   600
f99817977494 updated
cu
parents: 518
diff changeset
   601
f99817977494 updated
cu
parents: 518
diff changeset
   602
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
f99817977494 updated
cu
parents: 518
diff changeset
   603
\begin{frame}[c]
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   604
\frametitle{Man-in-the-Middle}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   605
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   606
Attack:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   607
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   608
\begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   609
\item \bl{$A$} sends public key  to \bl{$B$}  --- \bl{$C$} intercepts this message and send his own public key
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   610
\item \bl{$B$} sends public key  to \bl{$A$} --- \bl{$C$} intercepts this message and send his own public key
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   611
\item \bl{$A$} sends message encrypted with \bl{$C$}'s public key, \bl{$C$} decrypts it
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   612
with its private key, re-encrypts with \bl{$B$}'s public key 
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   613
\item similar for other direction
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   614
\end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   615
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   616
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   617
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   618
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   619
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   620
\begin{frame}[c]
555
f99817977494 updated
cu
parents: 518
diff changeset
   621
\frametitle{A MITM Attack}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   622
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   623
555
f99817977494 updated
cu
parents: 518
diff changeset
   624
\begin{center}
f99817977494 updated
cu
parents: 518
diff changeset
   625
\begin{tabular}{ll@{\hspace{2mm}}l}
f99817977494 updated
cu
parents: 518
diff changeset
   626
1. & \bl{$A \to E :$} & \bl{$K^{pub}_A$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   627
2. & \bl{$E \to B :$} & \bl{$K^{pub}_E$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   628
3. & \bl{$B \to E :$} & \bl{$K^{pub}_B$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   629
4. & \bl{$E \to A :$} & \bl{$K^{pub}_E$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   630
5. & \bl{$A \to E :$} & \bl{$\{A,m\}_{K^{pub}_E}$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   631
6. & \bl{$E \to B :$} & \bl{$\{E,m\}_{K^{pub}_B}$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   632
7. & \bl{$B \to E :$} & \bl{$\{B,m'\}_{K^{pub}_E}$}\smallskip\\
f99817977494 updated
cu
parents: 518
diff changeset
   633
8. & \bl{$E \to A :$} & \bl{$\{E,m'\}_{K^{pub}_A}$}
f99817977494 updated
cu
parents: 518
diff changeset
   634
\end{tabular}
f99817977494 updated
cu
parents: 518
diff changeset
   635
\end{center}\pause\medskip
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   636
555
f99817977494 updated
cu
parents: 518
diff changeset
   637
and \bl{$A$} and \bl{$B$} have no chance to detect it
f99817977494 updated
cu
parents: 518
diff changeset
   638
\end{frame}
f99817977494 updated
cu
parents: 518
diff changeset
   639
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   640
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   641
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   642
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
555
f99817977494 updated
cu
parents: 518
diff changeset
   643
% \begin{frame}[c]
f99817977494 updated
cu
parents: 518
diff changeset
   644
% \frametitle{Man-in-the-Middle}
f99817977494 updated
cu
parents: 518
diff changeset
   645
f99817977494 updated
cu
parents: 518
diff changeset
   646
% Potential Prevention?
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   647
555
f99817977494 updated
cu
parents: 518
diff changeset
   648
% \begin{itemize}
f99817977494 updated
cu
parents: 518
diff changeset
   649
% \item \bl{$A$} sends public key  to \bl{$B$}
f99817977494 updated
cu
parents: 518
diff changeset
   650
% \item \bl{$B$} sends public key  to \bl{$A$}
f99817977494 updated
cu
parents: 518
diff changeset
   651
% \item \bl{$A$} encrypts message with \bl{$B$}'s public key, send's {\bf half} of the message
f99817977494 updated
cu
parents: 518
diff changeset
   652
% \item \bl{$B$} encrypts message with \bl{$A$}'s public key, send's {\bf half} of the message
f99817977494 updated
cu
parents: 518
diff changeset
   653
% \item \bl{$A$} sends other half, \bl{$B$} can now decrypt entire message
f99817977494 updated
cu
parents: 518
diff changeset
   654
% \item \bl{$B$} sends other half, \bl{$A$} can now decrypt entire message
f99817977494 updated
cu
parents: 518
diff changeset
   655
% \end{itemize}\pause
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   656
555
f99817977494 updated
cu
parents: 518
diff changeset
   657
% %\bl{$C$} would have to invent a totally new message
f99817977494 updated
cu
parents: 518
diff changeset
   658
% \alert{Under which circumstances does this protocol prevent
f99817977494 updated
cu
parents: 518
diff changeset
   659
% MiM-attacks, or does it?}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   660
555
f99817977494 updated
cu
parents: 518
diff changeset
   661
%\end{frame}
f99817977494 updated
cu
parents: 518
diff changeset
   662
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
f99817977494 updated
cu
parents: 518
diff changeset
   663
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   664
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   665
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   666
\begin{frame}[c]
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   667
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   668
A Man-in-the-middle attack in real life:
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   669
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   670
\begin{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   671
\item the card only says yes to the terminal if the PIN is correct
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   672
\item trick the card in thinking transaction is verified by signature
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   673
\item trick the terminal in thinking the transaction was verified by PIN
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   674
\end{itemize}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   675
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   676
\begin{minipage}{1.1\textwidth}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   677
\begin{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   678
\mbox{}\hspace{-6mm}\includegraphics[scale=0.5]{../pics/chip-attack.png}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   679
\includegraphics[scale=0.3]{../pics/chipnpinflaw.png}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   680
\end{center}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   681
\end{minipage}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   682
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   683
\end{frame}
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   684
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   685
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   686
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
555
f99817977494 updated
cu
parents: 518
diff changeset
   687
% \begin{frame}[c]
f99817977494 updated
cu
parents: 518
diff changeset
   688
% \frametitle{Problems with EMV}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   689
555
f99817977494 updated
cu
parents: 518
diff changeset
   690
% \begin{itemize}
f99817977494 updated
cu
parents: 518
diff changeset
   691
% \item it is a wrapper for many protocols
f99817977494 updated
cu
parents: 518
diff changeset
   692
% \item specification by consensus (resulted unmanageable complexity)
f99817977494 updated
cu
parents: 518
diff changeset
   693
% \item its specification is 700 pages in English plus 2000+ pages for testing, additionally some 
f99817977494 updated
cu
parents: 518
diff changeset
   694
% further parts are secret
f99817977494 updated
cu
parents: 518
diff changeset
   695
% \item other attacks have been found
f99817977494 updated
cu
parents: 518
diff changeset
   696
% \end{itemize}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   697
555
f99817977494 updated
cu
parents: 518
diff changeset
   698
% \end{frame}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   699
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   700
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   701
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   702
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
555
f99817977494 updated
cu
parents: 518
diff changeset
   703
% \begin{frame}[c]
f99817977494 updated
cu
parents: 518
diff changeset
   704
% \frametitle{Protocols are Difficult}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   705
555
f99817977494 updated
cu
parents: 518
diff changeset
   706
% \begin{itemize}
f99817977494 updated
cu
parents: 518
diff changeset
   707
% \item even the systems designed by experts regularly fail\medskip
f99817977494 updated
cu
parents: 518
diff changeset
   708
% \item the one who can fix a system should also be liable for the losses\medskip
f99817977494 updated
cu
parents: 518
diff changeset
   709
% \item cryptography is often not the problem\bigskip\bigskip  
f99817977494 updated
cu
parents: 518
diff changeset
   710
% \end{itemize}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   711
555
f99817977494 updated
cu
parents: 518
diff changeset
   712
% \end{frame}
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   713
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   714
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   715
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   716
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   717
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   718
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   719
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   720
\begin{frame}[c]
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   721
\frametitle{Interlock Protocol}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   722
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   723
The interlock protocol (``best bet'' against MITM):
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   724
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   725
\begin{center}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   726
\begin{tabular}{ll@{\hspace{2mm}}l}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   727
1. & \bl{$A \to B :$} & \bl{$K^{pub}_A$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   728
2. & \bl{$B \to A :$} & \bl{$K^{pub}_B$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   729
3. & & \bl{$\{A,m\}_{K^{pub}_B} \;\mapsto\; H_1,H_2$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   730
   & & \bl{$\{B,m'\}_{K^{pub}_A} \;\mapsto\; M_1,M_2$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   731
4. & \bl{$A \to B :$} & \bl{$H_1$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   732
5. & \bl{$B \to A :$} & \bl{$\{H_1, M_1\}_{K^{pub}_A}$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   733
6. & \bl{$A \to B :$} & \bl{$\{H_2, M_1\}_{K^{pub}_B}$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   734
7. & \bl{$B \to A :$} & \bl{$M_2$}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   735
\end{tabular}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   736
\end{center}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   737
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   738
\end{frame}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   739
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   740
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   741
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   742
\begin{frame}[c]
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   743
\frametitle{Splitting Messages}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   744
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   745
\begin{center}
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   746
$\underbrace{\texttt{\Grid{0X1peUVTGJK+H70mMjAM8p}}}_{\bl{\{A,m\}_{K^{pub}_B}}}$
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   747
\end{center}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   748
 
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   749
\begin{center}
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   750
$\underbrace{\texttt{\Grid{0X1peUVTGJK}}}_{\bl{H_1}}$\quad
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   751
$\underbrace{\texttt{\Grid{+H70mMjAM8p}}}_{\bl{H_2}}$
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   752
\end{center}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   753
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   754
\begin{itemize}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   755
\item you can also use the even and odd bytes
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   756
\item the point is you cannot decrypt the halves, even if you
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   757
      have the key 
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   758
\end{itemize}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   759
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   760
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   761
\end{frame}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   762
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   763
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   764
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   765
\begin{frame}[c]
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   766
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   767
\begin{center}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   768
\begin{tabular}{l@{\hspace{9mm}}l}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   769
\begin{tabular}[t]{@{}l@{}}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   770
\bl{$A \to C : K^{pub}_A$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   771
\bl{$C \to B : K^{pub}_C$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   772
\bl{$B \to C : K^{pub}_B$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   773
\bl{$C \to A : K^{pub}_C$}\medskip\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   774
\bl{$\{A,m\}_{K^{pub}_C} \;\mapsto\; H_1,H_2$}\\
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   775
\bl{$\{B,m'\}_{K^{pub}_C} \;\mapsto\; M_1,M_2$}\bigskip\\
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   776
\bl{$\{C,a\}_{K^{pub}_B} \;\mapsto\; C_1,C_2$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   777
\bl{$\{C,b\}_{K^{pub}_A} \;\mapsto\; D_1,D_2$}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   778
\end{tabular} &
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   779
\begin{tabular}[t]{@{}l@{}}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   780
\bl{$A \to C : H_1$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   781
\bl{$C \to B : C_1$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   782
\bl{$B \to C : \{C_1, M_1\}_{K^{pub}_C}$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   783
\bl{$C \to A : \{H_1, D_1\}_{K^{pub}_A}$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   784
\bl{$A \to C : \{H_2, D_1\}_{K^{pub}_C}$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   785
\bl{$C \to B : \{C_2, M_1\}_{K^{pub}_B}$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   786
\bl{$B \to C : M_2$}\\
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   787
\bl{$C \to A : D_2$}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   788
\end{tabular}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   789
\end{tabular}
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   790
\end{center}\pause
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   791
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   792
\footnotesize
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   793
\bl{$m$} = How is your grandmother? \bl{$m'$} = How is the
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   794
weather today in London?
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   795
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   796
\end{frame}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   797
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   798
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   799
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   800
\begin{frame}[c]
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   801
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   802
\begin{itemize}
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   803
\item you have to ask something that cannot be imitated 
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   804
  (requires \bl{$A$} and \bl{$B$} know each other)
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   805
\item what happens if \bl{$m$} and \bl{$m'$} are voice
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   806
  messages?\bigskip\pause
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   807
483
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   808
\item So \bl{$C$} can either leave the communication unchanged,
337a8f5cb1ad updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 420
diff changeset
   809
      or invent a complete new conversation
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   810
      
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   811
\end{itemize}
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   812
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   813
\end{frame}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   814
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   815
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   816
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   817
\begin{frame}[c]
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   818
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   819
\begin{itemize}
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   820
\item the moral: establishing a secure connection from
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   821
      ``zero'' is almost impossible---you need to rely on some
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   822
      established trust\medskip
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   823
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   824
\item that is why PKI relies on certificates, which however are
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   825
      badly, badly realised
415
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   826
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   827
\end{itemize}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   828
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   829
\end{frame}
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   830
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
56bc53ba7c5b updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 381
diff changeset
   831
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
   832
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
   833
\begin{frame}[c]
555
f99817977494 updated
cu
parents: 518
diff changeset
   834
\frametitle{Car Transponder (HiTag2)}
f99817977494 updated
cu
parents: 518
diff changeset
   835
f99817977494 updated
cu
parents: 518
diff changeset
   836
\begin{enumerate}
f99817977494 updated
cu
parents: 518
diff changeset
   837
\item \bl{$C$} generates a random number \bl{$N$}
f99817977494 updated
cu
parents: 518
diff changeset
   838
\item \bl{$C$} calculates \bl{$(F,G) = \{N\}_K$}
f99817977494 updated
cu
parents: 518
diff changeset
   839
\item \bl{$C \to T$}: \bl{$N, F$}
f99817977494 updated
cu
parents: 518
diff changeset
   840
\item \bl{$T$} calculates \bl{$(F',G') = \{N\}_K$}
f99817977494 updated
cu
parents: 518
diff changeset
   841
\item \bl{$T$} checks that \bl{$F = F'$}
f99817977494 updated
cu
parents: 518
diff changeset
   842
\item \bl{$T \to C$}: \bl{$N, G'$}
f99817977494 updated
cu
parents: 518
diff changeset
   843
\item \bl{$C$} checks that \bl{$G = G'$}
f99817977494 updated
cu
parents: 518
diff changeset
   844
\end{enumerate}\pause
f99817977494 updated
cu
parents: 518
diff changeset
   845
f99817977494 updated
cu
parents: 518
diff changeset
   846
\small
f99817977494 updated
cu
parents: 518
diff changeset
   847
This process means that the transponder believes the car knows
f99817977494 updated
cu
parents: 518
diff changeset
   848
the key \bl{$K$}, and the car believes the transponder knows
f99817977494 updated
cu
parents: 518
diff changeset
   849
the key \bl{$K$}. They have authenticated themselves
f99817977494 updated
cu
parents: 518
diff changeset
   850
to each other, or have they?
f99817977494 updated
cu
parents: 518
diff changeset
   851
f99817977494 updated
cu
parents: 518
diff changeset
   852
\end{frame}
f99817977494 updated
cu
parents: 518
diff changeset
   853
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
f99817977494 updated
cu
parents: 518
diff changeset
   854
f99817977494 updated
cu
parents: 518
diff changeset
   855
f99817977494 updated
cu
parents: 518
diff changeset
   856
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
f99817977494 updated
cu
parents: 518
diff changeset
   857
\begin{frame}[c]
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   858
\frametitle{Trusted Third Parties}
252
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   859
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   860
Simple protocol for establishing a secure connection via a
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   861
mutually trusted 3rd party (server):
254
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   862
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   863
\begin{center}
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   864
\begin{tabular}{r@ {\hspace{1mm}}l}
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   865
\bl{$A \rightarrow S :$} & \bl{$A, B$}\\
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   866
\bl{$S \rightarrow A :$} & \bl{$\{K_{AB}, \{K_{AB}\}_{K_{BS}} \}_{K_{AS}}$}\\
254
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   867
\bl{$A \rightarrow B :$} & \bl{$\{K_{AB}\}_{K_{BS}} $}\\
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   868
\bl{$A \rightarrow B :$} & \bl{$\{m\}_{K_{AB}}$}\\
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   869
\end{tabular}
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   870
\end{center}
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   871
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   872
\end{frame}
254
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   873
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   874
252
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   875
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   876
\begin{frame}[c]
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   877
\frametitle{PKI: The Main Idea}
252
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   878
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   879
\begin{itemize}
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   880
\item the idea is to have a certificate authority (CA)
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   881
\item you go to the CA to identify yourself
254
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   882
\item CA: ``I, the CA, have verified that public key 
0d491b5654f9 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 253
diff changeset
   883
  \bl{$P^{pub}_{Bob}$} belongs to Bob''\bigskip
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   884
\item CA must be trusted by everybody\medskip
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   885
\item certificates are time limited, and can be revoked
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
   886
252
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   887
\item What happens if CA issues a false certificate? Who pays in case of loss? (VeriSign 
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   888
explicitly limits liability to \$100.)
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   889
\end{itemize}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
   890
252
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
   891
\end{frame}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
   892
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
   893
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   894
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   895
\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   896
\frametitle{PKI: Chains of Trust}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   897
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   898
\begin{center}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   899
  \begin{tikzpicture}[scale=1,
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   900
                      node/.style={
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   901
                      rectangle,rounded corners=3mm,
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   902
                      very thick,draw=black!50,minimum height=18mm, minimum width=23mm,
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   903
                      top color=white,bottom color=black!20}]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   904
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   905
  \node (A) at (0,0)  [node] {};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   906
  \node [below right] at (A.north west) 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   907
  {\small\begin{tabular}{@{}l}CA\\Root Cert.\end{tabular}};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   908
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   909
  \node (B) at (4,0)  [node] {};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   910
  \node [below right=1mm] at (B.north west) 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   911
 {\mbox{}\hspace{-1mm}\small
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   912
  \begin{tabular}{@{}l}Subordinate\\ CA\end{tabular}};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   913
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   914
  \node (C) at (8,0)  [node] {};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   915
  \node [below right] at (C.north west) 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   916
  {\small\begin{tabular}{@{}l}Server\\ Bank.com\end{tabular}};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   917
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   918
  \draw [->,line width=4mm] (A) -- (B); 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   919
  \draw [->,line width=4mm] (B) -- (C); 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   920
  
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   921
  \node (D) at (6,-3)  [node] {};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   922
  \node [below right] at (D.north west) 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   923
  {\small\begin{tabular}{@{}l}Browser\\ Root Store\end{tabular}};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   924
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   925
  \node (E) at (2,-3)  [node] {};
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   926
  \node [below right] at (E.north west) 
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   927
  {\small\begin{tabular}{@{}l}Browser\\ Vendor\end{tabular}};
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   928
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   929
  \draw [->,line width=4mm] (E) -- (D); 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   930
  \end{tikzpicture}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   931
\end{center}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   932
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   933
\begin{itemize}
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   934
\item CAs make almost no money anymore, because of stiff
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   935
  competition
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   936
\item browser companies are not really interested in security;
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   937
  only in market share
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   938
\end{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   939
  
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   940
\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   941
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
255
9cf486aea756 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 254
diff changeset
   942
9cf486aea756 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 254
diff changeset
   943
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
9cf486aea756 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 254
diff changeset
   944
\begin{frame}[c]
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   945
\frametitle{PKI: Weaknesses}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   946
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   947
CAs just cannot win (make any profit):\medskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   948
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   949
\begin{itemize}
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   950
\item there are hundreds of CAs, which issue millions of
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   951
      certificates and the error rate is small
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   952
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   953
\item users (servers) do not want to pay or pay as little as
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   954
      possible\bigskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   955
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   956
\item a CA can issue a certificate for any domain not needing
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   957
      any permission (CAs are meant to undergo audits,
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   958
      but\ldots DigiNotar)
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   959
      
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   960
\item if a CA has issued many certificates, it ``becomes too
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   961
      big to fail'' 
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   962
  
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   963
\item Can we be sure CAs are not just frontends of some 
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   964
      government organisation?  
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   965
       
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   966
\end{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   967
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   968
\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   969
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   970
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   971
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   972
\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   973
\frametitle{PKI: Weaknesses}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   974
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   975
\begin{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   976
420
c527a5142f2f updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 419
diff changeset
   977
\item many certificates are issued via Whois, whether you own
c527a5142f2f updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 419
diff changeset
   978
      the domain\ldots if you hijacked a domain, it is easy to
c527a5142f2f updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 419
diff changeset
   979
      obtain certificates\medskip
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   980
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   981
\item the revocation mechanism does not work (Chrome has given
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   982
      up on general revocation lists)\medskip
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
   983
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   984
\item lax approach to validation of certificates 
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   985
  (Have you ever bypassed certification warnings?)\medskip
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   986
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   987
\item sometimes you want to actually install invalid
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
   988
      certificates (self-signed)
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   989
   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   990
\end{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   991
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   992
\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   993
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   994
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   995
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   996
\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   997
\frametitle{PKI: Attacks}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   998
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
   999
\begin{itemize}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1000
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1001
\item Go directly after root certificates 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1002
  \begin{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1003
  \item governments can demand private keys\smallskip
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1004
  \item 10 years ago it was estimated that breaking a 1024 bit
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1005
        key takes one year and costs 10 - 30 Mio \$; this is now
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1006
        reduced to 1 Mio \$
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1007
   \end{itemize} 
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1008
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1009
\item Go after buggy implementations of certificate
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1010
      validation\smallskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1011
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1012
\item Social Engineering 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1013
  \begin{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1014
    \item in 2001 somebody pretended to be 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1015
    from Microsoft and asked for two code-signing 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1016
    certificates
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1017
    \end{itemize}\bigskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1018
\end{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1019
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1020
\small The eco-system is completely broken (it relies on
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1021
thousands of entities to do the right thing). Maybe DNSSEC
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1022
where keys can be attached to domain names is a way out.
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1023
256
e272713e34ff updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 255
diff changeset
  1024
\end{frame}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1025
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1026
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1027
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1028
\begin{frame}[c]
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1029
\frametitle{Real Attacks}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1030
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1031
\begin{itemize}
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1032
418
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1033
\item In 2011, DigiNotar (Dutch company) was the first CA that
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1034
      got compromised comprehensively, and where many
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1035
      fraudulent certificates were issued to the wild. It
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1036
      included approximately 300,000 IP addresses, mostly
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1037
      located in Iran. The attackers (in Iran?) were likely
ac2d2cb7dd82 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 417
diff changeset
  1038
      interested ``only'' in collecting gmail passwords.\medskip
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1039
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1040
\item The Flame malware piggy-bagged on this attack by
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1041
      advertising malicious Windows updates to some targeted
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1042
      systems (mostly in Iran, Israel, Sudan).
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1043
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1044
\end{itemize}
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1045
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1046
\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1047
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1048
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1049
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1050
\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1051
\frametitle{PKI is Broken}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1052
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1053
\begin{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1054
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1055
\item PKI and certificates are meant to protect you against
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1056
      MITM attacks, but if the attack occurs your are 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1057
      presented with a warning and you need to decide whether
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1058
      you are under attack.\medskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1059
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1060
\item Webcontent gets often loaded from 3rd-party servers,
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1061
      which might not be secured\medskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1062
     
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1063
\item Misaligned incentives: browser vendors are not
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1064
      interested in breaking webpages with invalid
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1065
      certificates     
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1066
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1067
\end{itemize}
52
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1068
416
708b80c825af updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 415
diff changeset
  1069
\end{frame}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1070
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1071
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1072
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1073
\begin{frame}[c]
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1074
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1075
Why are there so many invalid certificates?\bigskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1076
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1077
\begin{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1078
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1079
\item insufficient name coverage (www.example.com should
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1080
include example.com)
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1081
419
667a39dda86e updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 418
diff changeset
  1082
\item IoT: many appliances have web-based admin interfaces; 
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1083
  the manufacturer cannot know under which IP and domain name
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1084
  the appliances are run (so cannot install a valid certificate)
52
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1085
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1086
\item expired certificates, or incomplete chains of trust
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1087
      (servers are supposed to supply them)
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1088
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1089
\end{itemize}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1090
252
fa151c0a3cf4 updated slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 243
diff changeset
  1091
\end{frame}
123
2185acdb43bb added slides
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 90
diff changeset
  1092
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
52
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1093
417
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1094
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1095
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1096
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1097
%\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1098
%\frametitle{Best Practices}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1099
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1100
%{\bf Principle 1:} Every message should say what it means: the
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1101
%interpretation of a message should not depend on the
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1102
%context.\bigskip\pause
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1103
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1104
%{\bf Principle 2:} If the identity of a principal is essential
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1105
%to the meaning of a message, it is prudent to mention the
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1106
%principal’s name explicitly in the message (though
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1107
%difficult).\bigskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1108
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1109
%\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1110
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1111
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1112
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1113
%\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1114
%\frametitle{Best Practices}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1115
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1116
%{\bf Principle 3:} Be clear about why encryption is being
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1117
%done. Encryption is not wholly cheap, and not asking precisely
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1118
%why it is being done can lead to redundancy. Encryption is not
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1119
%synonymous with security.
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1120
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1121
%\small
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1122
%\begin{center}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1123
%Possible Uses of Encryption
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1124
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1125
%\begin{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1126
%\item Preservation of confidentiality: \bl{$\{X\}_K$} only those that have \bl{$K$} may recover \bl{$X$}.
%\item Guarantee authenticity: The partner is indeed some particular principal.
%\item Guarantee confidentiality and authenticity: binds two parts of a message --- 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1127
%\bl{$\{X,Y\}_K$} is not the same as \bl{$\{X\}_K$} and \bl{$\{Y\}_K$}.
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1128
%\end{itemize}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1129
%\end{center}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1130
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1131
%\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1132
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1133
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1134
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1135
%\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1136
%\frametitle{Best Practices}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1137
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1138
%{\bf Principle 4:} The protocol designers should know which
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1139
%trust relations their protocol depends on, and why the
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1140
%dependence is necessary. The reasons for particular trust
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1141
%relations being acceptable should be explicit though they will
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1142
%be founded on judgment and policy rather than on
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1143
%logic.\bigskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1144
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1145
%
%Example Certification Authorities: CAs are trusted to certify
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1146
%a key only after proper steps have been taken to identify the
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1147
%principal that owns it.
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1148
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1149
%\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1150
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1151
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1152
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1153
%\begin{frame}[c]
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1154
%\frametitle{Formal Methods}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1155
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1156
%Ross Anderson about the use of Logic:\bigskip
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1157
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1158
%\begin{quote}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1159
%Formal methods can be an excellent way of finding 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1160
%bugs in security protocol designs as they force the designer 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1161
%to make everything explicit and thus confront difficult design 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1162
%choices that might otherwise be fudged. 
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1163
%\end{quote}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1164
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1165
%\end{frame}
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1166
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1167
%
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1168
ca9295851eb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 416
diff changeset
  1169
52
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1170
\end{document}
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1171
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1172
%%% Local Variables:  
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1173
%%% mode: latex
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1174
%%% TeX-master: t
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1175
%%% End: 
be19f8a1fcf0 added slides 5
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
  1176