From 00a639c25d3c804f8e99567f7300239fc67f3a87 Mon Sep 17 00:00:00 2001
From: Tobias Eidelpes <tobias@eidelpes.info>
Date: Fri, 17 Jun 2022 11:10:01 +0200
Subject: [PATCH] Add solution for 4l

---
 exam/ex.tex | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/exam/ex.tex b/exam/ex.tex
index 8133008..d49900e 100644
--- a/exam/ex.tex
+++ b/exam/ex.tex
@@ -236,7 +236,15 @@
       for transmission of public keys so that they can fit in commonly used
       packet sizes.
 
-    \item \TODO
+    \item One disadvantage of the scheme is that it inherently has a non-zero
+      decoding failure rate (DFR). For ephemeral keys and the lowest security
+      level, the authors advertise an error probability of $14$ out of $1.2\cdot
+      10^9$ decodes. The DFR can be lowered by choosing different parameters,
+      but the rate is arguably still too high for practical use. 
+
+      For long term keys the authors state that 95 out of 100 keys (lowest
+      security level) provide a DFR of $2^{-64}$, which is also arguably too low
+      for extended use well into the future.
 
   \end{enumerate}