beamer.tex

   1 \documentclass[handout]{beamer}
   2 \usetheme{i4}
   3 \usepackage[utf8]{inputenc}
   4 \usepackage{tikz}
   5 \usepackage{multicol}
   6 \usepackage{listings}
   7 \lstloadlanguages{lisp}
   8
   9 \usetikzlibrary{svg.path,positioning,intersections}
  10 \usepgflibrary{shapes.geometric}
  11 \usepgflibrary{shapes.misc}
  12 \usepgflibrary{shapes.symbols}
  13
  14 \usepgflibrary{shapes}
  15 \usetikzlibrary{shapes,decorations,shadows}
  16 \usetikzlibrary{decorations.pathmorphing}
  17 \usetikzlibrary{decorations.shapes}
  18 \usetikzlibrary{fadings}
  19 \usetikzlibrary{patterns}
  20 \usetikzlibrary{calc}
  21 \tikzstyle{netdb}=[anchor=center,color=black,rectangle,draw,minimum
  22  size=1em,minimum height=.5em]
  23 \tikzstyle{client}=[fill=i4gray,rectangle,draw]
  24 \tikzstyle{chain}=[rectangle,draw,minimum size=1em,minimum height=.5em]
  25 \tikzstyle{arrow}=[->,thick,draw,shorten <=2pt,shorten >=2pt,]
  26 \tikzstyle{tunnel}=[fill=gray,shape=ellipse,minimum size=4em,minimum height=1.1em]
  27
  28 \newcommand{\iip}[1]{\textcolor{i4red}{#1}}
  29
  30 \author[Christoph Egger]{{\bf Christoph Egger}, Johannes Schlumberger, Christopher
  31   Kruegel, Giovanni Vigna}
  32 \title{Practical Attacks Against The I2P Network}
  33 \institute{Friedrich-Alexander University Erlangen-Nuremberg\\
  34 University of California, Santa Barbara}
  35 \date{October 25, 2013}
  36 \begin{document}
  37
  38 \begin{frame}[plain]
  39   \vspace{1.5em}
  40   \titlepage
  41   \begin{center}
  42   \includegraphics[width=0.2\paperwidth]{ucsbseal}
  43   \hspace{1.5em}
  44   \includegraphics[width=0.25\paperwidth]{streifenlogo}
  45   \end{center}
  46 \end{frame}
  47
  48 \begin{frame}
  49   \frametitle{Outline}
  50   \begin{multicols}{2}
  51     \begin{block}{What is I2P?}
  52       \begin{itemize}
  53       \item Tunnels
  54       \item Network Database
  55       \item \textcolor{gray}{Floodfill Participation}
  56       \item Thread model
  57       \end{itemize}
  58     \end{block}
  59     \begin{block}{Attacks}
  60       \begin{itemize}
  61       \item \textcolor{gray}{Floodfill Takeover Attack}
  62       \item Sybil Attack
  63       \item \textcolor{gray}{Eclipse Attack}
  64       \item Deanonymization Attack
  65       \end{itemize}
  66     \end{block}
  67     \begin{block}{Evaluation}
  68       \begin{itemize}
  69       \item \textcolor{gray}{Floodfill Takeover Attack}
  70       \item Sybil Attack
  71       \item \textcolor{gray}{Eclipse Attack}
  72       \item Deanonymization Attack
  73       \end{itemize}
  74     \end{block}
  75     \begin{block}{Conclusions}
  76       \begin{itemize}
  77       \item Limitations
  78       \item I2P Improvements
  79       \item \textcolor{gray}{Related Work}
  80       \end{itemize}
  81     \end{block}
  82   \end{multicols}
  83 \end{frame}
  84
  85 \begin{frame}
  86   \frametitle{Introduction I2P}
  87   \begin{itemize}\addtolength{\itemsep}{1\baselineskip}
  88   \item Solution for anonymous Communication
  89   \item Separated from the ``Internet'' -- \emph{Darknet}
  90   \item Fully distributed Design
  91   \item Based on Onion Routing
  92   \item Between 18,000 and 28,000 active users
  93   \end{itemize}
  94 \end{frame}
  95 \section{I2P}
  96 \begin{frame}
  97   \frametitle{I2P}
  98   \begin{multicols}{2}
  99     \begin{block}{Router}
 100       \begin{itemize}
 101       \item Handle Connections
 102       \item Provide Name Services
 103       \end{itemize}
 104     \end{block}
 105     \pause
 106     \begin{block}{Applications}
 107       \begin{itemize}
 108       \item Server, Client or P2P Software
 109       \item Sockets interface with TCP-like or UDP-like Semantics
 110       \end{itemize}
 111     \end{block}
 112     \pause
 113     \begin{figure}
 114       \centering
 115       \begin{tikzpicture}[scale=1.2]
 116         \tikzstyle{every node}=[font=\tiny]
 117         \node[minimum width=7em,minimum height=6em,draw=gray](clientpc) at (25mm,9mm) {};
 118         \node[above=0mm of clientpc.south] {User's Computer};
 119         \node[cloud,drop shadow,fill=white,draw,minimum
 120         width=4.5em,minimum height=2.5em](ip) at (22mm,27mm) {I2P};
 121         \node[client](client) at (22mm, 18mm) {I2P Router};
 122         \node[rectangle,draw,below=0mm of client.south east](app1) {Application};
 123         \node[rectangle,draw,below=0mm of app1.south](app2) {Application};
 124         \node[rectangle,draw,below=0mm of app2.south](app3) {Application};
 125
 126         \path[arrow] (app1.west) -| ([xshift=3.5mm]client.south west);
 127         \path[arrow] (app2.west) -| ([xshift=2.5mm]client.south west);
 128         \path[arrow] (app3.west) -| ([xshift=1.5mm]client.south west);
 129         \path[arrow] ([xshift=.5mm]client.north) -- ([xshift=.5mm]ip.south);
 130         \path[arrow] ([xshift=-.5mm]ip.south) -- ([xshift=-.5mm]client.north);
 131       \end{tikzpicture}
 132     \end{figure}
 133
 134   \end{multicols}
 135 \end{frame}
 136
 137 \begin{frame}
 138   \frametitle{Tunnels}
 139   \begin{itemize}
 140   \item using onion-routing for anonymity
 141   \item unidirectional
 142   \item paired for bi-directional communication
 143   \end{itemize}\pause
 144   \begin{block}{Client Tunnels}
 145     \begin{itemize}
 146     \item Used for Data Interactions
 147     \item Several pro Application
 148     \end{itemize}
 149   \end{block}
 150   \pause
 151   \begin{block}{Exploratory Tunnels}
 152     \begin{itemize}
 153     \item Used for Database interaction
 154     \item 2 to 3 per Node
 155     \end{itemize}
 156   \end{block}
 157 \end{frame}
 158
 159 \begin{frame}
 160   \frametitle{Network Database}
 161   \begin{itemize}
 162   \item<1-> Kademlia-like DHT based on \texttt{XOR}-distance run on
 163     320 super-nodes
 164   \item<2-> \iip{databaseRecord}\\
 165     Information named using a hash over their cryptographic Keys
 166   \item<3-> \iip{storageLocation}\\
 167     Hash over name and today's date
 168   \item<4-> \iip{routerInfo}\\
 169     Peer information: IP address, Port, Protocol, Keys
 170   \item<5-> \iip{leaseSet}\\
 171     Service Information: Entry tunnels, Keys
 172   \end{itemize}
 173   % \begin{multicols}{2}
 174   %   \begin{block}{\iip{routerInfo}}
 175   %     \begin{itemize}
 176   %     \item Peer information: IP address, Port, Protocol, Keys
 177   %     \end{itemize}
 178   %   \end{block}
 179   %   \begin{block}{\iip{leaseSet}}
 180   %     \begin{itemize}
 181   %     \item Service Information: Entry tunnels, Keys
 182   %     \end{itemize}
 183   %   \end{block}
 184   %   % \begin{figure}
 185   %   %   \centering
 186   %   %   \begin{tikzpicture}
 187   %   %     \node[draw,rectangle split, rectangle split parts=2] (lease) at (-3em,0) {\iip{leaseSet}\nodepart{second}\tiny{Keys}};
 188   %   %     \node[draw,rectangle split, rectangle split parts=2] (router) at (3em,0) {\iip{routerInfo}\nodepart{second}\tiny{Keys}};
 189   %   %     \node[draw,ellipse] (hashfn1) at (0,-3em) {\tiny{SHA256}};
 190   %   %     \node[draw,rectangle] (hash1) at (0,-5.5em) {\iip{resourceIdentifier}};
 191   %   %     \node[draw,rectangle,right=-0.1mm of hash1.east] (day) {Date};
 192
 193   %   %     \node[draw,ellipse] (hashfn1) at (0,-8em) {\tiny{SHA256}};
 194   %   %     \node[draw,rectangle] (resID) at (0,-10.5em) {\iip{storageLocation}};
 195   %   %   \end{tikzpicture}
 196   %   % \end{figure}
 197   % \end{multicols}
 198 \end{frame}
 199
 200 \begin{frame}
 201   \frametitle{Sample Interaction}
 202   \begin{figure}
 203     \centering
 204     \begin{tikzpicture}[scale=1.2]
 205       \tikzstyle{every node}=[font=\tiny]
 206 % netDB
 207       \foreach \sector in {%
 208         0, 1, 2, 3, 4, 5, 6, 7, 8, 9}%
 209       {
 210         \node[netdb](node\sector) at ({36 * (-\sector + .5)} : 10mm) {\sector};
 211       }
 212       \node at (0, 0) {netDB};
 213 % client
 214       \node[client](client) at (28mm, 12mm) {Server Router};
 215       \node[rectangle,draw,below=0mm of client.south west] {Application};
 216       \node[minimum width=7em,minimum height=4em,draw=gray](clientpc) at (25mm,9mm) {};
 217       \node[above=0mm of clientpc.south] {Server's System};
 218 % server
 219       \node[client](server) at (-42mm, 12mm) {Client Router};
 220       \node[rectangle,draw,below=0mm of server.south east] {Application};
 221       \node[minimum width=7em,minimum height=4em,draw=gray](clientpc) at (-38mm,9mm) {};
 222       \node[above=0mm of clientpc.south] {Client's System};
 223 % client client tunnel
 224       \node[chain,minimum size=6.5em,minimum height=2em,draw=gray](tunnel) at (16mm,20.5mm) {};
 225       \node[above=0mm of tunnel.north] {Server's data tunnel pair};
 226 %  \node[tunnel,minimum width=9.5em] at (16mm, 19mm) {};
 227 %  \node[tunnel,minimum width=9.5em] at (16mm, 22mm) {};
 228 %
 229       \node[chain] (cco1) at (23mm, 19mm) {};
 230       \path[arrow] ([xshift=4mm]client.north) |- (cco1.east);
 231       \node[chain] (cco2) at (16mm, 19mm) {};
 232       \path[arrow] (cco1.west) -- (cco2.east);
 233       \node[chain] (cco3) at (9mm, 19mm) {};
 234       \path[arrow] (cco2.west) -- (cco3.east);
 235       \node[chain] (cci1) at (23mm, 22mm) {};
 236       \path[arrow] (cci1.east) -| ([xshift=5mm]client.north);
 237       \node[chain] (cci2) at (16mm, 22mm) {};
 238       \path[arrow] (cci2.east) -- (cci1.west);
 239       \node[chain] (cci3) at (9mm, 22mm) {};
 240       \path[arrow] (cci3.east) -- (cci2.west);
 241 % server client tunnel
 242       \node[chain,minimum size=6.5em,minimum height=2em,draw=gray](tunnel) at (-30mm,20.5mm) {};
 243       \node[above=0mm of tunnel.north] {Client's data tunnel pair};
 244 %  \node[tunnel,minimum width=9.5em] at (-34mm, 19mm) {};
 245 %  \node[tunnel,minimum width=9.5em] at (-34mm, 22mm) {};
 246 %
 247       \node[chain] (csi1) at (-37mm, 19mm) {};
 248       \path[arrow,<-] ([xshift=-4mm]server.north) |- (csi1.west);
 249       \node[chain] (csi2) at (-30mm, 19mm) {};
 250       \path[arrow,<-] (csi1.east) -- (csi2.west);
 251       \node[chain] (csi3) at (-23mm, 19mm) {};
 252       \path[arrow,<-] (csi2.east) -- (csi3.west);
 253       \node[chain] (cso1) at (-37mm, 22mm) {};
 254       \path[arrow,<-] (cso1.west) -| ([xshift=-5mm]server.north);
 255       \node[chain] (cso2) at (-30mm, 22mm) {};
 256       \path[arrow,<-] (cso2.west) -- (cso1.east);
 257       \node[chain] (cso3) at (-23mm, 22mm) {};
 258       \path[arrow,<-] (cso3.west) -- (cso2.east);
 259 % client exploratory tunnel
 260       \node[chain,minimum size=4.5em,minimum height=2em,draw=gray](tunnel) at (-32.5mm,-3.5mm) {};
 261       \node[below=0mm of tunnel.south,align=center] {Client's exploratory\\tunnel pair};
 262 %  \node[tunnel,minimum width=7.5em] at (-36.5mm, 0mm) {};
 263 %  \node[tunnel,minimum width=7.5em] at (-36.5mm, -3mm) {};
 264 %
 265       \node[chain] (eo1) at (-36mm, -2mm) {};
 266       \path[arrow] ([xshift=-4mm]server.south) |- (eo1.west);
 267       \node[chain] (ei1) at (-36mm, -5mm) {};
 268       \path[arrow,<-] ([xshift=-5mm]server.south) |- (ei1.west);
 269       \node[chain] (eo2) at (-29mm, -2mm) {};
 270       \path[arrow] (eo1.east) -- (eo2.west);
 271       \node[chain] (ei2) at (-29mm, -5mm) {};
 272       \path[arrow,<-] (ei1.east) -- (ei2.west);
 273 % service lookup
 274       \draw[arrow,bend right=20,dashdotted] (eo2.east) to node[above=.8em,align=center] {service\\lookup} (node4.west);
 275       \draw[arrow,bend right=10,<-,dashdotted] (ei2.east) to node {} ([yshift=-1mm]node4.west);
 276 % data link
 277       \draw[arrow,bend left=15,dashdotted] (cco3.west) to node {} (csi3.east);
 278       \draw[arrow,bend right=15,dashdotted] (cci3.west) to node {} (cso3.east);
 279       \node at (-9mm,20.5mm) {Data connection};
 280     \end{tikzpicture}
 281   \end{figure}
 282 \end{frame}
 283
 284 \begin{frame}
 285   \frametitle{Thread Model}
 286   \begin{itemize}\addtolength{\itemsep}{1\baselineskip}
 287   \item Implicitly specified in terms of attacks considered
 288   \item Only allows local adversaries: No global view about traffic
 289     passing through the network
 290   \item Only allows limited number of malicious nodes -- around 20\,\%
 291     of \iip{netDB} super-nodes and 20\,\% of total nodes
 292   \item Secure cryptographic primitives
 293   \end{itemize}
 294 \end{frame}
 295
 296 \section{Attacks}
 297 \begin{frame}
 298   \frametitle{Sybil Attack}
 299   \begin{block}{Definition}
 300     In a Sybil Attack, the adversary utilizes multiple identities to
 301     break assumptions about the system
 302   \end{block}\pause
 303   \begin{block}{Goal}
 304     Gaining control over parts of the keyspace in the \iip{netDB} with
 305     limited resources
 306   \end{block}\pause
 307   \begin{block}{Challenge}
 308     Active identities require considerable resources to be useful
 309   \end{block}\pause
 310   \begin{block}{Solution}
 311     Compute a large pool of identities and only activate the relevant ones
 312   \end{block}
 313 \end{frame}
 314
 315 \begin{frame}
 316   \frametitle{Deanonymizing Users}
 317   \begin{block}{Goal}
 318     Given an user Alice and a resource R, we want to confirm or refute
 319     Alice using R with high probability.
 320   \end{block}\pause
 321   \begin{block}{Vulnerability}
 322     \begin{itemize}
 323     \item<2-> Nodes store their \iip{routerInfo} directly in the \iip{netDB}
 324     \item<3-> Nodes verify the storage 20 seconds later using one of their
 325       \iip{exploratory Tunnels}
 326     \item<4-> Nodes use the same \iip{exploratory Tunnel} again for
 327       resource lookups
 328     \end{itemize}
 329   \end{block}
 330 \end{frame}
 331
 332 \begin{frame}
 333   \frametitle{Deanonymizing Users}
 334   \begin{figure}
 335   \centering
 336 \begin{tikzpicture}[scale=1.4,font=\tiny]
 337 % netDB
 338   \foreach \sector in {%
 339     0, 1, 2, 3, 4, 5, 6, 7, 8, 9}%
 340   {
 341     \node[netdb](node\sector) at ({36 * (-\sector + .5)} : 12mm) {\sector};
 342   }
 343   \node at (0, 0) {netDB};
 344 % client
 345   \node[client](client) at (-45mm, 12mm) {Client};
 346 % store
 347   \draw[arrow,bend left=5,dashdotted] (client.north east) to node[above] {store} (node7.north west);
 348   \draw[arrow,<-,bend left=5,dashdotted] (client.east) to node {} (node7.west);
 349 % flood
 350   \draw[arrow,draw,bend right=15] (node7.south east) to node {} (node8.south west);
 351   \draw[arrow,draw,bend right=15] (node7.south east) to node[below] {replication} (node9.west);
 352   \draw[arrow,draw,bend left=15]  (node7.south east) to node {} (node6.north east);
 353 % tunnels
 354   \node[chain,minimum size=6em,minimum height=3.5em,draw=gray](tunnel) at (-35mm,-2.5mm) {};
 355   \node[below=2mm of tunnel.south] {exploratory tunnel pair};
 356 %  \node[tunnel] at (-35mm, 0mm) {};
 357   \node[chain] (ol) at (-40mm, 0mm) {};
 358   \node[chain] (oe) at (-30mm, 0mm) {};
 359 %  \node[tunnel] at (-35mm, -5mm) {};
 360   \node[chain] (il) at (-40mm, -5mm) {};
 361   \node[chain] (ie) at (-30mm, -5mm) {};
 362   \path[arrow] ([xshift=-1mm]client.south) |- (ol.west);
 363   \path[arrow,<-] ([xshift=-2mm]client.south) |- (il.west);
 364   \path[arrow] (ol.east) -- (oe.west);
 365   \path[arrow,<-] (il.east) -- (ie.west);
 366 % verify
 367   \draw[arrow,bend left=5,dashdotted] (oe.north east) to node[above] {verify} ([yshift=1mm]node6.west);
 368   \draw[arrow,bend left=15,<-,dashdotted] (ie.north east) to node {} (node6.west);
 369 %lookup
 370   \draw[arrow,bend right=15,dashdotted] (oe.south east) to node[above] {lookup} (node4.west);
 371   \draw[arrow,bend right=5,<-,dashdotted] (ie.south east) to node {} ([yshift=-1mm]node4.west);
 372 \end{tikzpicture}
 373 \end{figure}
 374 \end{frame}
 375
 376 \section{Evaluation}
 377 \begin{frame}
 378   \frametitle{Sybil Attack}
 379   \begin{block}{Generating identities}
 380     \begin{itemize}
 381     \item Building a Database of 50,000 identities takes around 30
 382       minutes on 12-core Xeon server
 383     \item 156 nodes on average between two adjacent database nodes
 384     \item All identities available to all malicious nodes
 385     \end{itemize}
 386   \end{block}\pause
 387   \begin{block}{Using identities}
 388     \begin{itemize}
 389     \item Malicious nodes can calculate the correct identities and
 390       change identity at any time
 391     \item Nodes coordinate to avoid duplicate identities
 392     \end{itemize}
 393   \end{block}
 394 \end{frame}
 395
 396 \begin{frame}
 397   \frametitle{Deanonyizing Attack}
 398   \begin{block}{Setup}
 399     \begin{itemize}
 400     \item 20 attacking nodes in Santa Barbara
 401       \begin{itemize}
 402       \item 10 nodes capturing resource lookups
 403       \item 10 nodes performing timing attack on \iip{routerInfo} storage
 404       \end{itemize}
 405     \item 6 monitoring nodes: 3 in Erlangen, 3 in Santa Barbara
 406     \end{itemize}
 407   \end{block}\pause
 408   \begin{block}{Results}
 409     \begin{itemize}
 410     \item 60\,\% of potentially observable links detected
 411     \item 52\,\% of attributed hits correct
 412     \item Working equally well for geographically remote Hosts
 413     \end{itemize}
 414   \end{block}
 415 \end{frame}
 416
 417 \begin{frame}
 418   \frametitle{Deanonymizing Users}
 419   \begin{figure}
 420   \centering
 421 \begin{tikzpicture}[scale=1.4,font=\tiny]
 422 % netDB
 423   \foreach \sector in {%
 424     0, 1, 2, 3, 4, 5, 6, 7, 8, 9}%
 425   {
 426     \node[netdb](node\sector) at ({36 * (-\sector + .5)} : 12mm) {\sector};
 427   }
 428   \node at (0, 0) {netDB};
 429 % client
 430   \node[client](client) at (-45mm, 12mm) {Client};
 431 % store
 432   \draw[arrow,bend left=5,dashdotted] (client.north east) to node[above] {store} (node7.north west);
 433   \draw[arrow,<-,bend left=5,dashdotted] (client.east) to node {} (node7.west);
 434 % flood
 435   \draw[arrow,draw,bend right=15] (node7.south east) to node {} (node8.south west);
 436   \draw[arrow,draw,bend right=15] (node7.south east) to node[below] {replication} (node9.west);
 437   \draw[arrow,draw,bend left=15]  (node7.south east) to node {} (node6.north east);
 438 % tunnels
 439   \node[chain,minimum size=6em,minimum height=3.5em,draw=gray](tunnel) at (-35mm,-2.5mm) {};
 440   \node[below=2mm of tunnel.south] {exploratory tunnel pair};
 441 %  \node[tunnel] at (-35mm, 0mm) {};
 442   \node[chain] (ol) at (-40mm, 0mm) {};
 443   \node[chain] (oe) at (-30mm, 0mm) {};
 444 %  \node[tunnel] at (-35mm, -5mm) {};
 445   \node[chain] (il) at (-40mm, -5mm) {};
 446   \node[chain] (ie) at (-30mm, -5mm) {};
 447   \path[arrow] ([xshift=-1mm]client.south) |- (ol.west);
 448   \path[arrow,<-] ([xshift=-2mm]client.south) |- (il.west);
 449   \path[arrow] (ol.east) -- (oe.west);
 450   \path[arrow,<-] (il.east) -- (ie.west);
 451 % verify
 452   \draw[arrow,bend left=5,dashdotted] (oe.north east) to node[above] {verify} ([yshift=1mm]node6.west);
 453   \draw[arrow,bend left=15,<-,dashdotted] (ie.north east) to node {} (node6.west);
 454 %lookup
 455   \draw[arrow,bend right=15,dashdotted] (oe.south east) to node[above] {lookup} (node4.west);
 456   \draw[arrow,bend right=5,<-,dashdotted] (ie.south east) to node {} ([yshift=-1mm]node4.west);
 457 \end{tikzpicture}
 458 \end{figure}
 459 \end{frame}
 460
 461 \begin{frame}
 462   \frametitle{Results for multiple Hits}
 463   \small{
 464   $N=144$, Number of time slices\\
 465   $q=0.001$, 7\,\% of total nodes accessing the resource once a day\\
 466   $x=0.52\cdot p + 0.48\cdot q$ \\
 467   $P(k~hits) = {N \choose k} x^k \cdot (1-x)^{N-k}$}
 468   \begin{figure}
 469     \centering
 470     \includegraphics[width=.7\textwidth]{graph}
 471   \end{figure}
 472 \end{frame}
 473
 474 \section{Conclusions}
 475
 476 \begin{frame}
 477   \frametitle{Limitations}
 478   \begin{itemize}\addtolength{\itemsep}{1\baselineskip}
 479   \item Only works reliable for longer/repeated resource access
 480   \item Less reliable for popular resources
 481   \item Needs extra resources per tracked user and per resource
 482   \end{itemize}
 483 \end{frame}
 484
 485 \begin{frame}
 486   \frametitle{I2P Improvements}
 487   \begin{itemize}\addtolength{\itemsep}{1\baselineskip}
 488   \item Limiting \iip{netDB} nodes per IPv4 network
 489   \item Ignoring new \iip{netDB} nodes
 490   \item Removing storage verification
 491   \item Randomizing the time delta
 492   \item Expiring tunnels after storage verification
 493   \end{itemize}
 494 \end{frame}
 495
 496 \begin{frame}
 497   \frametitle{Bibliography}
 498   \nocite{Mittal:2012}
 499   \nocite{Timpanaro:2011}
 500   \nocite{Herrmann:2011}
 501   \nocite{Douceur:2002}
 502   \nocite{Dingledine:2004}
 503   \nocite{Evans:2011}
 504   \bibliographystyle{plain}
 505   \tiny{\bibliography{../i2p}}
 506 \end{frame}
 507
 508 \end{document}
 509
 510 %%% Local Variables:
 511 %%% mode: latex
 512 %%% TeX-master: t
 513 %%% TeX-PDF-mode: t
 514 %%% End: