--- a/handouts/ho06.tex	Thu Dec 18 15:51:19 2014 +0000
+++ b/handouts/ho06.tex	Fri Dec 19 23:24:37 2014 +0000
@@ -394,6 +394,11 @@
 \ldots still to be completed (for example can be attacked by
 MITM attacks)
 
+\subsubsection*{Further Reading}
+
+Make sure you understand what NP problems
+are.\footnote{\url{http://en.wikipedia.org/wiki/NP_(complexity)}} They
+are the building blocks for zero-knowledge proofs.
 
 \end{document}