Module 8 Overview
March 1-7 · Reading: 9 pages · Due: Lab 5 · Estimated total: 6.5 hours
Symmetric cryptography would work beautifully if every pair of people already shared a secret key. They usually do not, and symmetric cryptography cannot help them get one. Two people who have never met, talking over a network run by strangers, have no safe way to agree on a key with symmetric tools alone, because anything they send to set one up can be read along the way.
Public-key cryptography solves that, by making one half of a key pair publishable. This week covers what that buys: encryption to someone you have never met, and signatures that prove a message came from a particular key and has not changed.
It also sets up the gap that week 10 exists to fill. A signature verifies against a key. Nothing this week tells you the key belongs to the person you think it does.
Learning Objectives
By the end of this week, the successful student will be able to:
- 3.3: Compare symmetric and public-key cryptography by key distribution, performance, and typical use.
- 3.4: Verify a digital signature.
- 3.5: Explain what a failed signature verification does and does not prove.
Assignments and Tasks
Due by Sunday at 11:59 p.m. Mountain Time
- Read 8.01 Readings and Lecture Notes and work through the worked example (2 hrs 30 min)
- Complete 8.02 Lab 5: Hashing and Signatures (1 hr 30 min, 38 points)
Next week is review and catch-up with no new material, so this is the last week of new content before the break.
Time Estimate
| Activity | Time |
|---|---|
| Reading (9 pages plus Nakov) | 1 hr 45 min |
The notes page and running sign_demo.py | 45 min |
| Lab 5 | 1 hr 30 min |
| Review and slack | 2 hrs 30 min |
| Total | ~6.5 hrs |