diff --git a/exam/ex.tex b/exam/ex.tex
index fe92231..0742647 100644
--- a/exam/ex.tex
+++ b/exam/ex.tex
@@ -133,7 +133,9 @@
 
     \item \TODO
 
-    \item \TODO
+    \item The length of the random nonce $N$ is $\unit[96]{bits}$. The expected
+      number of evaluations an attacker has to make to obtain a repeated nonce
+      is $2^{96/2} = 2^{48}$.
 
     \item \TODO