Encryption: symmetric (AES) and asymmetric (RSA) keys, data at rest and in transit

This week’s topics

Encryption: symmetric (AES) and asymmetric (RSA) keys, data at rest and in transit

1. Encryption techniques: prime factorisation and modular arithmetic, symmetric (AES) and asymmetric (RSA) encryption, data at rest vs. in transit (SSL/TLS, VPNs)
2. Strengths, weaknesses and ways encryption is broken

What you will be able to do

• 4.4 Explain the value of cryptography for a range of cyber security applications.
• 4.5 Explain the basic mathematical principles underlying encryption.
• 4.6 Analyse a variety of encryption techniques.

Activity

Start with this week’s video, then: Seminar, guided reading and a short written task: explain the value of cryptography for a range of cyber security applications.

Study materials

Videos

• Encryption tools to protect communication · Oak National Academy, Key Stage 4 (GCSE level) · for registered students

Further resources

• Foundations of Information Systems, 5.2: Firewalls, VPNs and encryption · PDF · OpenStax Foundations of Information Systems (2025), 5.2 on firewalls, VPNs and secure protocols, pp. 168–171 · for registered students
• An Introduction to Computer Networks, 5.1: Virtual Private Networks · PDF · Dordal, An Introduction to Computer Networks, release 2.0.11, 5.1: how a VPN works, pp. 135–136 · for registered students
• An Introduction to Computer Networks, 4.2.5: Wi-Fi Security · PDF · Dordal, An Introduction to Computer Networks, release 2.0.11, 4.2.5: WEP, WPA, WPA2, AES and EAP (a step up), pp. 114–121 · for registered students
• Measuring HTTPS adoption on the web · Open-access article · Felt et al. (2017), USENIX Security Symposium. How much of the Web uses HTTPS and why the HTTP-to-HTTPS shift matters. · for registered students