The key concepts are: Basics of Key Exchange; Diffie-Hellman, Diffie-Hellman Weaknesses, ECDH, and Passing Key Using Public Key. What you should know at the end of unit?

Understand how the Diffie-Hellman process works, with a simple example
Understand how the private key is used to check the identity of the sender, and how public key is used to preserve the privacy of the message.
Understand the basics of how Bob and Alice generate a shared key with ECC.

Presentations

Week 5 Presentation (lecture) - Key Exchange: here
Week 5 Presentation (PDF) - Key Exchange: here
Doodle lecture - Key Exchange: here

Lab

Week 5 Lab (PDF): here
Week 5 Lab (Demo): here

Sample Exam Questions

The following are sample questions for key exchange:

Eve listens to Bob and Alice's communcication for their Diffie-Hellman handshaking. In order to generate the same key as Bob and Alice, which values will Eve try to determine, and how is it likely to be difficult to gain these?
For the following key exchanges, Bob generates x, and Alice generates y. Prove the shared key. Examples
- x=3, y=4, g=4 and N=7. Share=1.
- x=6, y=15, g=5 and N=23. Share=2.
- x=5, y=7, g=10 and N=541. Share=193.
- x=6, y=15, g=5 and N=23. Share=2.
- x=7, y=7, g=5 and N=11. Share=9.
- x=7, y=9, g=8 and N=13. Share=5.
- x=5, y=4, g=2969 and N=9929. Share=8106.
- x=6, y=5, g=3881 and N=125. Share=792.
- x=3, y=4, g=3623 and N=1153. Share=939.
Why are Forward Security and Ephemeral so important for the security of your keys?

Examples

Diffie-Hellman Examples: here
ECDH Step-by-step: here

Quick demos

Introduction to Diffie-Hellman: here
ECDH here
Picking the Generator Value (G): here

Any questions?

We are on Teams. Ask Bill here.