diff --git a/exam/ex.tex b/exam/ex.tex
index aa7055d..f586c92 100644
--- a/exam/ex.tex
+++ b/exam/ex.tex
@@ -353,7 +353,11 @@
       finding an isomorphism for a specific commitment and challenge which
       matches the response is hard.
 
-    \item \TODO
+    \item The size of the signature comprises the commitment, which is a hash,
+      and the response. The hash function is chosen to be $\unit[256]{bits}$ and
+      the response is $\lceil\log_2 1107\rceil\cdot 1107 = \unit[12.177]{kbit} =
+      \unit[1522.125]{bytes}$. In total, the signature is
+      $\unit[1554.125]{bytes}$ big.
 
     \item \TODO