# HG changeset patch
# User Christian Urban <christian dot urban at kcl dot ac dot uk>
# Date 1416351876 0
# Node ID 0cdfa8ef4aa282ebc5295c28cb1ae4c2c5c27b92
# Parent  edbd731e8beeca34df259fe3c859e9ba0b7c1dc0
updated

diff -r edbd731e8bee -r 0cdfa8ef4aa2 slides/slides08.pdf
Binary file slides/slides08.pdf has changed
diff -r edbd731e8bee -r 0cdfa8ef4aa2 slides/slides08.tex
--- a/slides/slides08.tex	Tue Nov 18 12:24:17 2014 +0000
+++ b/slides/slides08.tex	Tue Nov 18 23:04:36 2014 +0000
@@ -50,18 +50,61 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-% student prticipation
 \begin{frame}
-\frametitle{Bitcoins}
+\frametitle{Interlock Protocol}
+
+invented by  Ron Rivest and Adi Shamir (198X?)
 
 \begin{center}
-\Huge\bf ?
+\begin{tabular}{ll@{\hspace{2mm}}l}
+1. & $A \to B :$ & $K^{pub}_A$\smallskip\\
+2. & $B \to A :$ & $K^{pub}_B$\smallskip\\
+3. & & $\{A,m\}_{K^{pub}_B} \;\mapsto\; H_1,H_2$\\
+   & & $\{B,m'\}_{K^{pub}_A} \;\mapsto\; M_1,M_2$\\
+4. & $A \to B :$ & $H_1$\smallskip\\
+5. & $B \to A :$ & $\{H_1, M_1\}_{K^{pub}_A}$\smallskip\\
+6. & $A \to B :$ & $\{H_2, M_1\}_{K^{pub}_B}$\smallskip\\
+7. & $B \to A :$ & $M_2$
+\end{tabular}
 \end{center}
 
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}
+\frametitle{Car \& Transponder}
+
+\begin{enumerate}
+\item $C$ generates a random number $N$
+\item $C$ calculates $\{N\}_K \mapsto F,G$
+\item $C \to T$: $N, F$
+\item $T$ calculates $\{N\}_K \mapsto F',G'$
+\item $T$ checks that $F = F'$
+\item $T \to C$: $N, G'$
+\item $C$ checks that $G = G'$
+\end{enumerate}
+
+Does the car authenticate the transponder? Does the
+transponder authenticate the car?
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% student prticipation
+%\begin{frame}
+%\frametitle{Bitcoins}
+%
+%P2P, 21 Mio, $10^-8$, Mt~Gox, value decreased?, anonymity, 
+%Silk Road, verification incentive, puzzle, SHA-256, slow 
+%transactions, 
+%
+%\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[t]
 \frametitle{Bitcoins from 10,000m}
 
@@ -629,15 +672,19 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[t]
-\frametitle{But I did not Inhale}
+\frametitle{But I did not Inhale\ldots}
 
 \begin{center}
 \includegraphics[scale=0.4]{../pics/bitcointornetwork.png}
 \end{center}
 
-ledger is public forever; everybody can inspect
+\only<1>{
+ledger is public ``forever''; everybody can inspect
 how money was transferred from which address to
-which address
+which address; maybe not ideal for money laundering}
+\only<2>{
+You should use a new pp-pair for \alert{every} transaction;
+but few do (merchants). A design flaw(?): combining transactions.}
 
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
@@ -647,20 +694,17 @@
 \frametitle{Anonymity}
 \small
 
-Bitcoins may not be ideal for money laundering because all
-transactions are public.
-
-How anonymous is Bitcoin? Many people claim that Bitcoin can
+``How anonymous is Bitcoin? Many people claim that Bitcoin can
 be used anonymously. This claim has led to the formation of
 marketplaces such as Silk Road (and various successors), which
 specialize in illegal goods. However, the claim that Bitcoin
-is anonymous is a myth. The block chain is public, meaning
-that it’s possible for anyone to see every Bitcoin transaction
-ever. Although Bitcoin addresses aren’t immediately associated
-to real-world identities, computer scientists have done a
-great deal of work figuring out how to de-anonymize
-“anonymous” social networks. The block chain is a marvellous
-target for these techniques.
+is anonymous is a \underline{myth}. The block chain is public,
+meaning that it’s possible for anyone to see every Bitcoin
+transaction ever. Although Bitcoin addresses aren’t
+immediately associated to real-world identities, computer
+scientists have done a great deal of work figuring out how to
+de-anonymize `anonymous' social networks. The block chain is a
+marvellous target for these techniques.''
 
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
@@ -689,6 +733,23 @@
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[t]
+\frametitle{Take Home Points}
+
+
+\begin{itemize}
+  \item Don't gamble! I am not a first mover in such things.
+  \item Cool idea, but I am sure there will be a Bitcoin~2.0.
+  \item It still depends on a lot of old-fashioned security 
+  (e.g.~keeping private-keys secret)\bigskip
+
+  \item Having now the knowledge how it works, go back
+  and listen to what people/media make of it. 
+\end{itemize} 
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%