add text and *generated* pdf

doc/report.tex

@@ -11,7 +11,7 @@
   ]{tubsartcl}
 \usepackage[utf8x]{inputenc}
 
-\usepackage[ngerman]{babel}
+%\usepackage[ngerman]{babel}
 
 \usepackage{multicol}
 
@@ -54,22 +54,24 @@ line/.style={-latex}   % the lesser the width the greater will be the diagram wi
 \section{Simple combinatorics}
 
 \section{XOR cipher}
+\begin{figure}[h]
+    \centering
 \begin{tikzpicture}  
   \node[block] (m1) {$M_1$};  
   \node[block,below=of m1] (k1) {$K$};
-  \node[block,below=of k1] (c1) {$C_1$};
+  \node[block,below=of k1] (c1) {$C_x$};
   \node at ($(m1)!0.5!(k1)$){$\oplus$};
   \node at ($(k1)!0.5!(c1)$){$=$};
-  \node[block,text width=2cm, right=of m1] (mgen) {$C_1 \oplus K$};
+  \node[block,text width=2cm, right=of m1] (mgen) {$C_x \oplus K$};
   \node[xshift=-2mm] at ($(m1)!0.5!(mgen)$){$=$};
   \node[draw,inner xsep=5mm,inner ysep=5mm,fit=(mgen)(m1)(k1)(c1)](g){};
 
   \node[block, right=of m1, xshift=8cm] (m2) {$M_2$};  
   \node[block,below=of m2] (k2) {$K$};
-  \node[block,below=of k2] (c2) {$C_2$};
+  \node[block,below=of k2] (c2) {$C_y$};
   \node at ($(m2)!0.5!(k2)$){$\oplus$};
   \node at ($(k2)!0.5!(c2)$){$=$};
-  \node[block,text width=2cm, left=of k2] (kgen) {$M_2 \oplus C_2$};
+  \node[block,text width=2cm, left=of k2] (kgen) {$M_2 \oplus C_y$};
   \node[xshift=2mm] at ($(k2)!0.5!(kgen)$){$=$};
   \node[draw, inner xsep=5mm,inner ysep=5mm,fit=(kgen)(m2)(k2)(c2)](h){};
 
@@ -78,7 +80,14 @@ line/.style={-latex}   % the lesser the width the greater will be the diagram wi
 
   \draw[->] (c1) -| ([xshift=-1cm]mgen);
   \draw[->] (kgen) -| ([xshift=1cm]mgen);
-
 \end{tikzpicture}  
+\caption{This Diagram shows how an Attacker can calculate the Key $K$ and the Message $M_1$.}
+\end{figure}
+A few requirements must be satisfied in order to get hold of the $K$ and the $M_1$:
+\begin{itemize}
+    \item $M_2$ must be longer than $M_1$ or $K$, so that the key can be calculated in at least the needed length.
+    \item A successfully decoded message must be distinguishable from an unsuccessfully decoded message, so that the 
+        cipher texts $C_x$ and $C_y$ can be exchanged if necessary.
+\end{itemize}
 
 \end{document}