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% beamer stuff + −
\renewcommand{\slidecaption}{APP 09, King's College London, 27 November 2012}+ −
\newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}% for definitions+ −
\newcommand{\bl}[1]{\textcolor{blue}{#1}}+ −
+ −
\begin{document}+ −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}<1>[t]+ −
\frametitle{%+ −
\begin{tabular}{@ {}c@ {}}+ −
\\+ −
\LARGE Access Control and \\[-3mm] + −
\LARGE Privacy Policies (9)\\[-6mm] + −
\end{tabular}}\bigskip\bigskip\bigskip+ −
+ −
%\begin{center}+ −
%\includegraphics[scale=1.3]{pics/barrier.jpg}+ −
%\end{center}+ −
+ −
\normalsize+ −
\begin{center}+ −
\begin{tabular}{ll}+ −
Email: & christian.urban at kcl.ac.uk\\+ −
Of$\!$fice: & S1.27 (1st floor Strand Building)\\+ −
Slides: & KEATS (also homework is there)\\+ −
\end{tabular}+ −
\end{center}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Last Week}+ −
+ −
Recall, the Schroeder-Needham (1978) protocol is vulnerable to replay attacks.+ −
+ −
\begin{center}+ −
\begin{tabular}{@{}r@ {\hspace{1mm}}l@{}}+ −
\bl{$A \rightarrow S :$} & \bl{$A, B, N_A$}\\+ −
\bl{$S \rightarrow A :$} & \bl{$\{N_A, B, K_{AB},\{K_{AB}, A\}_{K_{BS}} \}_{K_{AS}}$}\\+ −
\bl{$A \rightarrow B :$} & \bl{$\{K_{AB}, A\}_{K_{BS}} $}\\+ −
\bl{$B \rightarrow A :$} & \bl{$\{N_B\}_{K_{AB}}$}\\+ −
\bl{$A \rightarrow B :$} & \bl{$\{N_B-1\}_{K_{AB}}$}\\+ −
\end{tabular}+ −
\end{center}\pause+ −
+ −
Fix: Replace messages 2 and 3 to include a timestamp:\bigskip+ −
+ −
\begin{minipage}{1.1\textwidth}+ −
\begin{center}+ −
\begin{tabular}{@{\hspace{-2mm}}r@ {\hspace{1mm}}l@{}}+ −
\bl{$S \rightarrow A :$} & \bl{$\{B, K_{\!AB}, T_S, \!\{K_{\!AB}, A, T_S\}_{K_{BS}} \}_{K_{AS}}$}\\+ −
\bl{$A \rightarrow B :$} & \bl{$\{K_{AB}, A, T_S\}_{K_{BS}} $}\\+ −
\end{tabular}+ −
\end{center}+ −
\end{minipage}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[t]+ −
\frametitle{Denning-Sacco Fix}+ −
+ −
Denning-Sacco (1981) suggested to add the timestamp, but omit the handshake:\bigskip+ −
+ −
\begin{minipage}{1.1\textwidth}+ −
\begin{center}+ −
\begin{tabular}{@{\hspace{-2mm}}r@ {\hspace{1mm}}l@{}}+ −
\bl{$A \rightarrow S :$} & \bl{$A, B$}\\+ −
\bl{$S \rightarrow A :$} & \bl{$\{B, K_{\!AB}, T_S, \!\{K_{\!AB}, A, T_S\}_{K_{BS}} \}_{K_{AS}}$}\\+ −
\bl{$A \rightarrow B :$} & \bl{$\{K_{AB}, A, T_S\}_{K_{BS}} $}\\+ −
\textcolor{lightgray}{$B \rightarrow A :$} & \textcolor{lightgray}{$\{N_B\}_{K_{AB}}$}\\+ −
\textcolor{lightgray}{$A \rightarrow B :$} & \textcolor{lightgray}{$\{N_B-1\}_{K_{AB}}$}\\+ −
\end{tabular}+ −
\end{center}+ −
\end{minipage}\bigskip+ −
+ −
they argue \bl{$A$} and \bl{$B$} can check that the messages are not replays of earlier + −
runs, by checking the time difference with when the protocol is last used+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[t]+ −
\frametitle{\begin{tabular}{@{}c@{}}Denning-Sacco-Lowe Fix of Fix\end{tabular}}+ −
+ −
Lowe (1997) disagreed and said the handshake should be kept, + −
otherwise:\bigskip + −
+ −
\begin{minipage}{1.1\textwidth}+ −
\begin{center}+ −
\begin{tabular}{@{\hspace{-7mm}}r@ {\hspace{1mm}}l@{}}+ −
\bl{$A \rightarrow S :$} & \bl{$A, B$}\\+ −
\bl{$S \rightarrow A :$} & \bl{$\{B, K_{\!AB}, T_S, \!\{K_{\!AB}, A, T_S\}_{K_{BS}} \}_{K_{AS}}$}\\+ −
\bl{$A \rightarrow B :$} & \bl{$\{K_{AB}, A, T_S\}_{K_{BS}} $}\\+ −
\bl{$I(A) \rightarrow B :$} & \bl{$\{K_{AB}, A, T_S\}_{K_{BS}} $}\hspace{5mm}\textcolor{black}{replay}\\+ −
\end{tabular}+ −
\end{center}+ −
\end{minipage}\bigskip+ −
+ −
When is this a problem?\pause\medskip+ −
+ −
Assume \bl{$B$} is a bank and the message is ``Draw \pounds{1000} from \bl{$A$}'s+ −
account and transfer it to \bl{$I$}.''+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[t]+ −
\frametitle{Privacy}+ −
+ −
\begin{minipage}{1.05\textwidth}+ −
\begin{itemize}+ −
\item we \alert{do} want that government data is made public (free maps for example)+ −
\item we \alert{do not} want that medical data becomes public (similarly tax data, school + −
records, job offers)\bigskip+ −
\item personal information can potentially lead to fraud + −
(identity theft)+ −
\end{itemize}\pause+ −
+ −
{\bf ``The reality'':}+ −
\only<2>{\begin{itemize}+ −
\item London Health Programmes lost in June unencrypted details of more than 8 million people+ −
(no names, but postcodes and details such as gender, age and ethnic origin)+ −
\end{itemize}}+ −
\only<3>{\begin{itemize}+ −
\item also in June Sony, got hacked: over 1M users' personal information, including passwords, email addresses, home addresses, dates of birth, and all Sony opt-in data associated with their accounts.+ −
\end{itemize}}+ −
\end{minipage}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Privacy and Big Data}+ −
+ −
Selected sources of ``Big Data'':\smallskip{}+ −
+ −
\begin{itemize}+ −
\item Facebook + −
\begin{itemize}+ −
\item 40+ Billion photos (100 PB)+ −
\item 6 Billion messages daily (5 - 10 TB)+ −
\item 900 Million users + −
\end{itemize}+ −
\item Common Crawl+ −
\begin{itemize}+ −
\item covers 3.8 Billion webpages (2012 dataset)+ −
\item 50 TB of data+ −
\end{itemize}+ −
\item Google+ −
\begin{itemize}+ −
\item 20 PB daily (2008)+ −
\end{itemize}+ −
\item Twitter+ −
\begin{itemize}+ −
\item 7 Million users in the UK+ −
\item a company called Datasift is allowed to mine all tweets since 2010+ −
\item they charge 10k per month for other companies to target advertisement+ −
\end{itemize}+ −
\end{itemize}\pause+ −
+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Cookies\ldots}+ −
+ −
``We have published a new cookie policy. It explains what cookies are + −
and how we use them on our site. To learn more about cookies and + −
their benefits, please view our cookie policy.\medskip+ −
+ −
If you'd like to disable cookies on this device, please view our information + −
pages on 'How to manage cookies'. Please be aware that parts of the + −
site will not function correctly if you disable cookies. \medskip+ −
+ −
By closing this + −
message, you consent to our use of cookies on this device in accordance + −
with our cookie policy unless you have disabled them.''+ −
+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Scare Tactics}+ −
+ −
The actual policy reads:\bigskip+ −
+ −
``As we explain in our Cookie Policy, cookies help you to get the most + −
out of our websites.\medskip+ −
+ −
If you do disable our cookies you may find that certain sections of our + −
website do not work. For example, you may have difficulties logging in + −
or viewing articles.''+ −
+ −
+ −
+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Netflix Prize}+ −
+ −
Anonymity is \alert{necessary} for privacy, but \alert{not} enough!\bigskip+ −
+ −
\begin{itemize}+ −
\item Netflix offered in 2006 (and every year until 2010) a 1 Mio \$ prize for improving their movie rating algorithm+ −
\item dataset contained 10\% of all Netflix users (appr.~500K)+ −
\item names were removed, but included numerical ratings as well as times of rating+ −
\item some information was \alert{perturbed} (i.e., slightly modified)+ −
\end{itemize}+ −
+ −
\hfill{\bf\alert{All OK?}}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Re-identification Attack}+ −
+ −
Two researchers analysed the data: + −
+ −
\begin{itemize}+ −
\item with 8 ratings (2 of them can be wrong) and corresponding dates that can have a margin 14-day error, 98\% of the+ −
records can be identified+ −
\item for 68\% only two ratings and dates are sufficient (for movie ratings outside the top 500)\bigskip\pause+ −
\item they took 50 samples from IMDb (where people can reveal their identity)+ −
\item 2 of them uniquely identified entries in the Netflix database (either by movie rating or by dates)+ −
\end{itemize}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{}+ −
+ −
\begin{itemize}+ −
\item Birth data, postcode and gender (unique for\\ 87\% of the US population)+ −
\item Preferences in movies (99\% of 500K for 8 ratings)+ −
\end{itemize}\bigskip+ −
+ −
Therefore best practices / or even law (HIPAA, EU): + −
+ −
\begin{itemize}+ −
\item only year dates (age group for 90 years or over), + −
\item no postcodes (sector data is OK, similarly in the US)\\+ −
\textcolor{gray}{no names, addresses, account numbers, licence plates}+ −
\item disclosure information needs to be retained for 5 years+ −
\end{itemize}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{How to Safely Disclose Information?}+ −
+ −
\only<1>{+ −
\begin{itemize}+ −
\item Assume you make a survey of 100 randomly chosen people.+ −
\item Say 99\% of the surveyed people in the 10 - 40 age group have seen the+ −
Gangnam video on youtube.\bigskip+ −
+ −
\item What can you infer about the rest of the population? + −
\end{itemize}}+ −
\only<2>{+ −
\begin{itemize}+ −
\item Is it possible to re-identify data later, if more data is released. \bigskip\bigskip\pause+ −
+ −
\item Not even releasing only aggregate information prevents re-identification attacks.+ −
(GWAS was a public database of gene-frequency studies linked to diseases;+ −
you only needed partial DNA information in order+ −
to identify whether an individual was part of the study --- DB closed in 2008) + −
\end{itemize}}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Differential Privacy}+ −
+ −
\begin{center}+ −
User\;\;\;\; + −
\begin{tabular}{c}+ −
tell me \bl{$f(x)$} $\Rightarrow$\\+ −
$\Leftarrow$ \bl{$f(x) + \text{noise}$}+ −
\end{tabular}+ −
\;\;\;\;\begin{tabular}{@{}c}+ −
Database\\+ −
\bl{$x_1, \ldots, x_n$}+ −
\end{tabular}+ −
\end{center}+ −
+ −
+ −
\begin{itemize}+ −
\item \bl{$f(x)$} can be released, if \bl{$f$} is insensitive to+ −
individual entries \bl{$x_1, \ldots, x_n$}\\+ −
\item Intuition: whatever is learned from the dataset would be learned regardless of whether+ −
\bl{$x_i$} participates\bigskip\pause + −
+ −
\item Noised needed in order to prevent queries:\\ Christian's salary $=$ + −
\begin{center}+ −
\bl{\large$\Sigma$} all staff $-$ \bl{\large$\Sigma$} all staff $\backslash$ Christian+ −
\end{center} + −
\end{itemize}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{Adding Noise}+ −
+ −
Adding noise is not as trivial as one would wish:+ −
+ −
\begin{itemize}+ −
\item If I ask how many of three have seen the Gangnam video and get a result+ −
as follows + −
+ −
\begin{center}+ −
\begin{tabular}{l|c}+ −
Alice & yes\\+ −
Bob & no\\+ −
Charlie & yes\\+ −
\end{tabular}+ −
\end{center}+ −
+ −
then I have to add a noise of \bl{$1$}. So answers would be in the+ −
range of \bl{$1$} to \bl{$3$}+ −
+ −
\bigskip+ −
\item But if I ask five questions for all the dataset (has seen Gangnam video, is male, below 30, \ldots),+ −
then one individual can change the dataset by \bl{$5$}+ −
\end{itemize}+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
+ −
+ −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[t]+ −
\frametitle{\begin{tabular}{@{}c@{}}Tor, Anonymous Webbrowsing\end{tabular}}+ −
+ −
\begin{itemize}+ −
\item initially developed by US Navy Labs, but then opened up to the world + −
\item network of proxy nodes+ −
\item a Tor client establishes a ``random'' path to the destination server (you cannot trace back where the information came from)\bigskip\pause+ −
\end{itemize}+ −
+ −
\only<2>{+ −
\begin{itemize}+ −
\item malicious exit node attack: someone set up 5 Tor exit nodes and monitored the traffic:+ −
\begin{itemize}+ −
\item a number of logons and passwords used by embassies (Usbekistan `s1e7u0l7c', while+ −
Tunesia `Tunesia' and India `1234')+ −
\end{itemize}+ −
\end{itemize}}+ −
\only<3>{+ −
\begin{itemize}+ −
\item bad apple attack: if you have one insecure application, your IP can be tracked through Tor+ −
\begin{itemize}+ −
\item background: 40\% of traffic on Tor is generated by BitTorrent+ −
\end{itemize}+ −
\end{itemize}}+ −
+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[t]+ −
\frametitle{\begin{tabular}{@{}c@{}}Skype Secure Communication\end{tabular}}+ −
+ −
\begin{itemize}+ −
\item Skype used to be known as a secure online communication (encryption cannot be disabled), + −
but \ldots\medskip+ −
+ −
\item it is impossible to verify whether crypto algorithms are correctly used, or whether there are backdoors.\bigskip+ −
+ −
\item recently someone found out that you can reset the password of somebody else's+ −
account, only knowing their email address (needed to suspended the password reset feature temporarily)+ −
\end{itemize}+ −
+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
+ −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{\begin{tabular}{@{}c@{}}Take Home Point\end{tabular}}+ −
+ −
According to Ross Anderson: \bigskip+ −
\begin{itemize}+ −
\item Privacy in a big hospital is just about doable.\medskip+ −
\item How do you enforce privacy in something as big as Google+ −
or complex as Facebook? No body knows.\bigskip+ −
+ −
Similarly, big databases imposed by government+ −
\end{itemize}+ −
+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+ −
\mode<presentation>{+ −
\begin{frame}[c]+ −
\frametitle{\begin{tabular}{@{}c@{}}Next Week\end{tabular}}+ −
+ −
Homework: Which areas should I focus on?+ −
+ −
+ −
\end{frame}}+ −
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + −
+ −
\end{document}+ −
+ −
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