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 						<a href="slides/#2-3" class="topic-slides-btn"><i class="icon ph-duotone ph-projector-screen"></i>Slides</a>
 						<span class="topic-number">Topic 2.3</span>
 						<h4 class="topic-title"><i class="icon ph-duotone ph-chalkboard-teacher"></i>Secure Messaging</h4>
-						<p class="topic-overview">This topic traces the evolution of secure messaging from early failures to modern protocols, examining how cryptographic innovation has shaped private communication. We begin with PGP's usability challenges and fundamental limitations, understanding why "Johnny Can't Encrypt" despite decades of effort. The topic then explores Off-the-Record (OTR) messaging's revolutionary features—forward secrecy through ephemeral keys, deniable authentication via MACs instead of signatures, and automatic key exchange—demonstrating how synchronous protocols solved many of PGP's problems. We dive deep into authenticated key exchange protocols like SIGMA, examining how they prevent man-in-the-middle attacks while maintaining identity protection. The discussion covers proper key derivation functions (HKDF) for deriving multiple keys from shared secrets, addressing the shortcomings of ad-hoc approaches. We then transition to Signal's asynchronous messaging architecture, analyzing X3DH key exchange and the Double Ratchet's elegant combination of symmetric and Diffie-Hellman ratcheting. The topic critically examines post-compromise security's promises versus reality, revealing through formal analysis why perfect healing is impossible in practical systems that must handle state loss. We also contrast Signal's approach with alternatives like Telegram's controversial design choices. Throughout, we'll analyze the fundamental trade-offs between security guarantees, usability, and real-world deployment constraints that shape how billions of messages are protected daily. We'll also examine modern extensions including secure group messaging protocols like MLS (Messaging Layer Security) that scale encrypted conversations to thousands of participants, and post-quantum secure messaging advances such as Apple's PQ3 and Signal's PQXDH that protect against future quantum attackers.</p>
+						<p class="topic-overview">This topic traces the evolution of secure messaging from early failures to modern protocols, examining how cryptographic innovation has shaped private communication. We begin with PGP's usability challenges and fundamental limitations, understanding why "Johnny Can't Encrypt" despite decades of effort. The topic then explores Off-the-Record (OTR) messaging's revolutionary features—forward secrecy through ephemeral keys, deniable authentication via MACs instead of signatures, and automatic key exchange—demonstrating how synchronous protocols solved many of PGP's problems. We dive deep into authenticated key exchange protocols like SIGMA, examining how they prevent man-in-the-middle attacks while maintaining identity protection. The discussion covers proper key derivation functions (HKDF) for deriving multiple keys from shared secrets, addressing the shortcomings of ad-hoc approaches. We then transition to Signal's asynchronous messaging architecture, analyzing X3DH key exchange and the Double Ratchet's elegant combination of symmetric and Diffie-Hellman ratcheting. The topic critically examines post-compromise security's promises versus reality, revealing through formal analysis why perfect healing is impossible in practical systems that must handle state loss. We also contrast Signal's approach with alternatives like Telegram's controversial design choices. Throughout, we'll analyze the fundamental trade-offs between security guarantees, usability, and real-world deployment constraints that shape how billions of messages are protected daily. We'll also examine modern extensions including secure group messaging protocols like MLS (Messaging Layer Security) that scale encrypted conversations to thousands of participants.</p>
 						<div class="topic-readings">
 							<h5><i class="icon ph-duotone ph-book-open-text"></i>Required Readings</h5>
 							<ul>