From ff265f5c741de36d459e7db3e27c24af7d49ff16 Mon Sep 17 00:00:00 2001
From: Trance-0 <60459821+Trance-0@users.noreply.github.com>
Date: Tue, 24 Feb 2026 16:03:01 -0600
Subject: [PATCH] updates

---
 content/CSE4303/CSE4303_L12.md                |  24 ++++++++++++++++++
 content/CSE4303/_meta.js                      |   1 +
 .../CSE4303/DNS_cache_poisoning.png           | Bin
 3 files changed, 25 insertions(+)
 create mode 100644 content/CSE4303/CSE4303_L12.md
 rename {content => public}/CSE4303/DNS_cache_poisoning.png (100%)

diff --git a/content/CSE4303/CSE4303_L12.md b/content/CSE4303/CSE4303_L12.md
new file mode 100644
index 0000000..dd07637
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+++ b/content/CSE4303/CSE4303_L12.md
@@ -0,0 +1,24 @@
+# CSE4303 Introduction to Computer Security (Lecture 12)
+
+## Asymmetric Encryption
+
+### Motivation
+
+#### Symmetric key exchange: TTPs
+
+Idea: Trusted Third Party (TTP) is always-available key manager
+
+- Assume secure channel exists between every user and TTP
+  - KA = shared key between user A and TTP
+- Generates/distributes keys to user pairs on demand
+  - KAB = shared key between user A and user B
+
+Symmetric-key encryption: challenges
+
+1. Key storage: one per user pair, $O(n^2)$ total for $n$ users
+2. Key exchange: how to do it over non-secure channel?
+
+### Key Exchange
+
+[Diffie-Hellman](https://notenextra.trance-0.com/CSE442T/CSE442T_L16/#diffie-helmann-key-exchange)
+
diff --git a/content/CSE4303/_meta.js b/content/CSE4303/_meta.js
index 55d7bd9..067a816 100644
--- a/content/CSE4303/_meta.js
+++ b/content/CSE4303/_meta.js
@@ -15,4 +15,5 @@ export default {
     CSE4303_L9: "Introduction to Computer Security (Lecture 9)",
     CSE4303_L10: "Introduction to Computer Security (Lecture 10)",
     CSE4303_L11: "Introduction to Computer Security (Lecture 11)",
+    CSE4303_L12: "Introduction to Computer Security (Lecture 12)",
 }
diff --git a/content/CSE4303/DNS_cache_poisoning.png b/public/CSE4303/DNS_cache_poisoning.png
similarity index 100%
rename from content/CSE4303/DNS_cache_poisoning.png
rename to public/CSE4303/DNS_cache_poisoning.png