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Class 2 Internet security

Homework 2

For each of the following systems, research and document 3 parts what threat does it address? what’s the trust model? what’s the residual risk?

  • PGP (end to end email security)
  • SSH (secure remote access)
  • VPN / IPsec (network-layer tunneling)
  • MACsec (link-layer encryption)
  • DNS Security (DNSSEC & DNS spoofing)
  • IDS / IPS (detection vs. prevention)

“Create an graphic from Security System.docx,” image generated by Gemini AI Tool, June, 29, 2026.

References:

PGP Libert, Timothy, et al. “SoK: Securing Email — A Stakeholder-Based Analysis.” arXiv, April 2018. https://arxiv.org/pdf/1804.07706. Lella, Ioannis, et al. “Challenging the Trustworthiness of PGP: Is the Web-of-Trust Tear-Proof?” ResearchGate, 2015. https://www.researchgate.net/publication/283083265.

SSH Encryption Consulting. “The Best Methods to Protect Your SSH Keys.” March 5, 2026. https://www.encryptionconsulting.com/the-best-methods-to-protect-your-ssh-keys/. Wendlandt, Dan, David G. Andersen, and Adrian Perrig. “Perspectives: Improving SSH-style Host Authentication with Multi-Path Probing.” USENIX Annual Technical Conference, 2008. https://www.usenix.org/legacy/events/usenix08/tech/full_papers/wendlandt/wendlandt_html/index.html.

VPN / IPsec Proton VPN. “Understanding the VPN Threat Model.” February 13, 2026. https://protonvpn.com/blog/threat-model. Al-Shaer, Ehab, and Hazem Hamed. “Modeling and Verification of IPSec and VPN Security Policies.” ResearchGate, December 2005. https://www.researchgate.net/publication/4195870.

MACsec Nile. “What Is MACsec?” August 6, 2024. https://nilesecure.com/network-security/what-is-macsec. FS Community. “MACsec Explained: Security for Enterprise Networks.” October 13, 2021. https://community.fs.com/blog/macsec-a-cool-security-option-for-your-enterprise-switch.html. Common Criteria. PP-Module for MACsec Ethernet Encryption, Version 1.0. December 16, 2022. https://commoncriteria.github.io/pp/MACsec/MACsec-release.pdf.

DNS Security / DNSSEC Cloudflare. “DNS Security.” Cloudflare Learning Center. Accessed June 29, 2026. https://www.cloudflare.com/learning/dns/dns-security/. Imperva. “What Is DNSSEC.” December 20, 2023. https://www.imperva.com/learn/application-security/dnssec/. UpGuard. “DNS Security Extensions (DNSSEC) and Cybersecurity Risk.” July 4, 2025. https://www.upguard.com/blog/dnssec-risk.

IDS / IPS Eventus Security. “Intrusion Detection System (IDS): Types and How It Works.” September 23, 2025. https://eventussecurity.com/cybersecurity/soc/intrusion-detection-system/. Imperva. “Intrusion Detection and Prevention.” December 20, 2023. https://www.imperva.com/learn/application-security/intrusion-detection-prevention/. Wikipedia. “Intrusion Detection System.” Last modified June 2026. https://en.wikipedia.org/wiki/Intrusion_detection_system.