slides

1 files changed, 71 insertions, 6 deletions

diff --git a/presentation/slides.tex b/presentation/slides.tex
index 269927a..4fe658a 100644
--- a/presentation/slides.tex
+++ b/presentation/slides.tex
@@ -269,13 +269,52 @@ Byzantine \emph{Set-Union} Consensus
 %----------------------------
 
 \begin{frame}
-\frametitle{How does a payment work?}
+\frametitle{What is happening under the hood?}
+  Setup / Reserve Creation
   \begin{enumerate}
-    \item Customer creates reserve key pair
+    \item Customer has list of trusted exchange / auditor (= exchange CA) public keys
+    \item Customer downloads latest key material (response signing / denominations) and wire information from exchange
+    \item Customer creates reserve key pair (ephemeral)
     \item Customer sends transaction with reserve public key in payment instructions to the exchange
   \end{enumerate}
 \end{frame}
 
+\begin{frame}
+\frametitle{What is happening under the hood?}
+  Withdrawal
+  \begin{enumerate}
+    \item Customer creates coin key pair (public key is coin identity, private key used to authorize operations with coin)
+    \item Customer blinds coin public key, sends withdraw request (signed with reserve pub) to exchange
+    \item Exchange signs blinded coin
+    \item Customer unblinds the signature
+  \end{enumerate}
+\end{frame}
+
+\begin{frame}
+\frametitle{What is happening under the hood?}
+  Spending
+  \begin{enumerate}
+    \item Merchant sends signed \emph{contract terms} to customer
+    \item Customer signs contract terms with the private key(s) of the coins used to pay.
+      In each signature, the fraction of the coin spent is specified.
+    \item Merchant receives these signatures in \emph{deposit permissions},
+      with also include the exchange's signatures on the coins and a hash of the contract terms
+    \item Merchant sends deposit permissions to the exchange
+    \item Exchange marks coins as (partially) spent
+    \item Exchange aggregates deposit permissions for some time
+    \item Exchange sends payment (e.g. bank money) to merchant
+  \end{enumerate}
+\end{frame}
+
+\begin{frame}
+\frametitle{What is happening under the hood?}
+  Getting anonymous change
+  \begin{enumerate}
+    \item Customer obtains anonymous coins as change for partially spent coins
+    \item More on details later ...
+  \end{enumerate}
+\end{frame}
+
 %----------------------------
 
 \begin{frame}
@@ -402,15 +441,24 @@ $\Rightarrow$ Naive refresh protocol enables tax evasion
     \item exchange's bank transactions
     \item merchant's deposit (probabilistic selection)
   \end{itemize}
+  
+  \vfill
+
   Compromise Scenarios (simplified):
   \begin{itemize}
-    \item 
+    \item Exchage's signing key compromised $\Rightarrow$ 
+    \item Exchage's denomination compromised $\Rightarrow$
   \end{itemize}
 \end{frame}
 
 
 \begin{frame}
 \frametitle{Denomination Key Revocation}
+  \begin{itemize}
+    \item 
+  \end{itemize}
+
+  $\Rightarrow$ Financial loss of the exchange limited to ???
 \end{frame}
 
 %----------------------------
@@ -438,10 +486,22 @@ $\Rightarrow$ Naive refresh protocol enables tax evasion
 
 %----------------------------
 
-\begin{frame}{Taler Protocols}
+\begin{frame}{Taler Cryptography}
+  We use a few ancient constructions:
+  \begin{itemize}
+  \item Cryptographic hash function (1989)
+  \item Blind signature (1983)
+  \item Schnorr signature (1989)
+  \item Diffie-Hellman key exchange (1976)
+  \item Cut-and-choose zero-knowledge proof (1985)
+  \end{itemize}
+  But of course we use modern instantiations.
 \end{frame}
 
-\begin{frame}{Refresh details}
+\begin{frame}{Refresh Protocol}
+  \begin{itemize}
+    \item Use key exchange 
+  \end{itemize}
 \end{frame}
 
 %----------------------------
@@ -508,7 +568,12 @@ Additional features (tipping, ...)
 
 \begin{frame}
 \frametitle{Alternatives?}
-Talk about web payments.
+W3C Web Payments?  No, only concerned with showing payment request in browser UI.
+
+Proprietary Systems?
+
+Blockchain?
+
 \end{frame}
 
 %----------------------------