1) The Boxentriq site has a large number of code generators for Caesar shifts, transposition ciphers, pigpen, Vignere codes and more. This is a great resource for generating and understanding a large number of codes. One of the best resources online.
2) CIMT Code resources – a fantastic resource for teachers with a large number of ready made worksheets and teacher notes on lots of different codes.
3) Khan Academy code breaking videos– a large number of short videos looking at both codes through history and more modern code methods.
4) Simon Singh’s Black Chamber is another excellent resource for code breaking methods – use computation methods to crack a host of codes. You can also conduct frequency analysis here. Simon Singh’s The Code Book is also an excellent read.
1) Additional resources for creating Vignere codes
2) Additional resources for creating Semaphore codes
3) Morse Code generator
4) Nrich has a nice article about the history of codes and mathematics
5) Reverse text, flip text, flip wording and more here.
6) Learn how to use the One Time Pad – a favourite coding method of spies in the Second World War.