--- a/slides/slides08.tex	Wed Nov 11 01:26:19 2015 +0000
+++ b/slides/slides08.tex	Thu Nov 12 08:25:22 2015 +0000
@@ -61,6 +61,59 @@
 %\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[t]
+\frametitle{Last Week's Survey}
+
+{\bf About Bitcoins:}
+
+\begin{textblock}{2.5}(11.5,10)
+\begin{bubble}[2.5cm]
+\it anonymous? 
+\end{bubble}
+\end{textblock}
+
+\begin{textblock}{5}(3.5,4)
+\begin{bubble}[5cm]
+\it cannot be controlled by the government?
+\end{bubble}
+\end{textblock}
+
+\begin{textblock}{4}(2,9)
+\begin{bubble}[4cm]
+\it untracable spending of money?
+\end{bubble}
+\end{textblock}
+
+\begin{textblock}{5.7}(3,13)
+\begin{bubble}[5.7cm]
+\it it takes 0..10 mins to pay with Bitcoins
+\end{bubble}
+\end{textblock}
+
+\begin{textblock}{5.6}(8,7)
+\begin{bubble}[5.6cm]
+\it Should one mine for Bitcoins?
+\end{bubble}
+\end{textblock}
+
+\begin{textblock}{2}(12,12.5)
+\begin{bubble}[2cm]
+\it mined by GPUs
+\end{bubble}
+\end{textblock}
+
+\begin{textblock}{3.6}(10,2.3)
+\begin{bubble}[3.6cm]
+\it can be lost or stolen
+\end{bubble}
+\end{textblock}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
+
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[t]
 \frametitle{Bitcoins from 10,000m}
@@ -71,7 +124,7 @@
   (max 21 Mio bitcoins---deflationary currency) 
 \item mined by solving special puzzles involving hashes
 \item transaction history (ledger/blockchain) is P2P distributed (12 GB)
-\item two ``mining pools'' produce\\ currently more than 50\% 
+\item three ``mining pools'' produce\\ currently more than 50\% 
   of bitcoins 
 \item can be stolen and also lost
 \item anonymous?\pause
@@ -140,7 +193,6 @@
 \begin{itemize}
 \item no-one else could have created that message
 \item Alice cannot deny the ``intend'' of sending Bob money\pause\bigskip
-\item forgery possible only after Alice created the string
 \item Q: What is money?\\ 
   A: Well a string like above
   (or later messages like that)
@@ -161,7 +213,7 @@
 
 \begin{itemize}
 \item Alice could keep sending Bob this message over and over
-      again (did she mean to send 10 ICs?)\pause
+      again (did she mean to send 10 ICs?)\bigskip\pause
 \item we need to have a serial number
 \begin{center}
 \bl{$\{\text{I, Alice, am giving Bob infocoin \#1234567.}\}_{K^{priv}_{Alice}}$}
@@ -178,14 +230,14 @@
 \begin{frame}[c]
 \frametitle{No Banks Please}
 
-With banks we could implement:
+With banks we could implement:\medskip
 
 \begin{itemize}
 \item Bob asks the bank whether the infocoin with that serial
       number belongs to Alice and
 \item Alice hasn’t already spent this infocoin.\bigskip 
 \item If yes, then Bob tells the bank he accepts the infocoin.
-\item The bank updates the records to show that the infocoin
+\item The bank updates the records (ledger) to show that the infocoin
       with that serial number is now in Bob’s possession and
       no longer belongs to Alice.
 \end{itemize}
@@ -262,7 +314,7 @@
 register)?\\[-10mm]\mbox{}\pause
 
 \begin{center}
-\hspace{15mm}\includegraphics[scale=0.35]{../pics/bitcoindisagreement.png}
+\hspace{15mm}\includegraphics[scale=0.31]{../pics/bitcoindisagreement.png}
 \end{center}
 
 \end{frame}
@@ -519,6 +571,7 @@
 \footnotesize
 BTCC, the largest mining pool, has limited its members to 
 not solve more than 6 blocks in a row.
+\hfill\url{https://blockchain.info/pools}
 
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
@@ -536,12 +589,65 @@
 this address
 
 \item there are $2^{160}$ possibilities\\ 
-(no check for duplicates)
+(no check for duplicates)\bigskip\pause
+
+\item transactions contain ``payment scripts''
+ (non-Turing-complete scripting language)\bigskip
+ 
+ \small simplest script: pay-to-public-key
 \end{itemize}
 
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[t]
+\frametitle{Multi-Signature Addresses}
+
+\begin{itemize}
+\item \ldots Bitcoin Improvement Proposal\bigskip\pause
+\item pay-to-public-key (explained so far)
+\item pay-to-script-hash (since 2012)\bigskip\pause
+
+can specify: requires \bl{M} out of \bl{N} signatures\medskip
+
+{\small for example\\
+1-of-2: me and my wife, or\\
+2-of-2 in banking/companies}
+
+\end{itemize}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[t]
+\frametitle{Dispute Mediation}
+
+\begin{itemize}
+\item say, client and (online) merchant do not trust 
+  each other\bigskip\pause
+
+\item 2-of-3: mutually trusted escrow service
+  \begin{enumerate}
+  \item client sends money to 2-of-3 transaction
+  \item merchant sends out goods
+  \item if goods are OK, client sends signed transaction
+    to merchant, merchant can sign and receive the money
+    (publish in blockchain)
+  \item if goods are defective, merchant sends signed transaction
+    to client, client can sign and receive the money back
+  \item if client and merchant disagree, then they ask escrow
+  servive who signs a transaction and sends it to ``winning''
+  party 
+ \end{enumerate}
+\end{itemize}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]
 \frametitle{A Transaction Msg}
@@ -672,7 +778,7 @@
 how money was transferred from which address to
 which address; maybe not ideal for money laundering}
 \only<2>{
-You should use a new pp-pair for \alert{every} transaction;
+You should use a new PKI-pair for \alert{every} transaction;
 but few do (merchants). A design flaw(?): combining transactions.}
 
 \end{frame}
@@ -697,6 +803,28 @@
 
 \end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
+\begin{frame}[t]
+\frametitle{Other Cryto-Currencies}
+
+Coloured Coins:
+
+\begin{itemize}
+  \item record a 1 bitcoin transfer, say, and give it a
+        ``colour'' 
+        
+  \item the transaction stands for a share in ``Foo Inc, UK''.
+  
+    
+  \item only makes sense if the share is much more
+  valueable than just 1 Bc.          
+\end{itemize} 
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[t]
 \frametitle{Bitcoin vs Gov}