29 lines
2.4 KiB
Markdown
29 lines
2.4 KiB
Markdown
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# Ideas for later problem sets
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```latex
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\item (5 points) \textbf{TLS Under Attack:}
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An advanced persistent threat (APT) group has compromised several Certificate Authorities and can issue valid certificates for any domain.
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\begin{enumerate}
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\item Analyze exactly how this compromise allows attacks against TLS connections, even when users see the "secure" padlock icon.
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\item Design countermeasures that could be deployed by browser vendors to detect and prevent these attacks. Consider both technical and usability constraints.
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\item Evaluate certificate pinning as a solution: when does it work, when does it fail, and how should it be deployed?
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\item Compare your solutions to Certificate Transparency. What attacks does CT prevent, and what attacks does it miss?
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\end{enumerate}
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\item (5 points) \textbf{Signal's Double Ratchet Design Challenge:}
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You're designing the next version of Signal's messaging protocol and want to improve upon the current Double Ratchet algorithm.
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\begin{enumerate}
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\item Analyze the trade-off between security and performance in the current design: why does Signal perform a new DH exchange for each message direction rather than just once per conversation?
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\item Design an optimization that reduces the number of DH operations while maintaining the same security properties. What compromises would you accept?
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\item Consider a group messaging scenario with 100 participants. How would you adapt your design to provide forward secrecy and post-compromise security for group conversations?
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\end{enumerate}
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\item (5 points) \textbf{Quantum Timeline Decision Making:}
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You're the CTO of a company building a secure messaging app expected to launch in 2028 and remain secure until 2040. Intelligence reports suggest large-scale quantum computers might exist by 2035, but with significant uncertainty (could be 2030 or 2045).
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\begin{enumerate}
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\item Design a migration strategy that balances current performance needs with future quantum threats. What algorithms do you deploy now, and when do you plan upgrades?
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\item Analyze the "harvest now, decrypt later" threat: what data in your system needs protection beyond 2035, and how does this influence your cryptographic choices?
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\item Evaluate the trade-offs between early adoption of post-quantum cryptography (larger keys, unproven security) versus delayed migration (quantum vulnerability risk).
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\end{enumerate}
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```
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