Lockdown Course: Introduction to Cryptography

Lockdown course: Introduction to Cryptography

Hi all! Well, due to the lockdown, I can’t do any teaching for a few months. So, I thought I’d try to do some teaching online. My YouTube stuff will continue to exist, but right now I miss teaching in small groups.


The course: Introduction to Cryptography
The course consists of five 80-minute sessions given across one week (Monday to Friday). See below for specific dates.

The course is an introduction to the mathematics of cryptography. The course starts with simple ciphers that have been used for thousands of years, and explains how these ciphers were broken. We will then move to more difficult ciphers, including an explanation of the famous Enigma machine and how that was broken. We will then finish with an explanation of the ciphers we use today on the internet.

The five sessions are:
Monoalphabetic ciphers
Monoalphabetic ciphers (continued)
Polyalphabetic ciphers
RSA (Internet encryption)


There will be an optional assessment for those who want to take it. This consists of five code breaking questions based on the topics we cover. I will mark your work and give feedback. I give everyone the assessment questions in the second session. You can choose to take the assessment in advance or anytime before the end of the course. See fees below.


Course leader
I’m James Grime. I’m a mathematician and lecturer. You might have seen me on the YouTube channel numberphile.


The course is a mathematics course, and you would need to be comfortable with school-level mathematics, i.e. basic algebra.

Otherwise, the course is self-contained and will introduce all necessary ideas such as modular arithmetic, probability, number theory and proof.

The course will be given in English.

There are no reading requirements.


Who is this course suitable for?
The course is suitable for those aged 16+
The course is written assuming you have done schools maths, but not university-level maths. 
It suitable for people interested in learning some new mathematics, in particular how is applies to cryptography.

It is not suitable for under 16s.
The course is not suitable for those already familiar with cryptography, or more advanced mathematics.

Note that this is a maths course, not a computer science course. (I’m not a computer science person, so you would be disappointed).


Course notes
You will receive notes-with-gaps. These notes contain all the waffle, but the mathematics is missing. We fill-in these notes as we go along. Here is an example page.

You will also receive a large font option. Here is an example page.

You will receive these notes before your first session.

You will either need to print these notes, or use software that allows you to write on a pdf (while following the lecture on Zoom).

I will be using free software Xodo to write on the pdf.


The course will be delivered on Zoom. Zoom is free to use. Click here to download Zoom.


I have two courses coming up:
Monday 18th May – Friday 22nd May. 1600-1730 (British Summer Time). Limit: 20 participants.
Monday 1st June – Friday 5th June. 1000-1130 (British Summer Time). Limit: 20 participants.

Note that there is a limit to the number of participants.

One week contains morning sessions (for me in the UK), the other week contains afternoon sessions. I’m hoping this will allow people in different time zones to join.


The fee is £75 for the week (that’s five 80-minute sessions). 
The (optional) assessment fee is £20.

You can register below (via shopify). 
Course notes and Zoom login information will be sent the Friday before your course.

Please note: I’m not a corporation. You will be dealing with me as an individual. This is more like a small study group, and hopefully a nice distraction during lockdown.

If you don’t trust me, don’t send me your money.



Register here via shopify