Show students the Cybersecurity jobs video as evidence that cryptographic jobs are in high demand.
Use the resource ‘Caesar code activities’ (XLS), issue the students a spreadsheet challenge.
First decide if a working spreadsheet is given to students with some parts to complete, or if students will work with the teacher in class to develop the formulas. (This second method is preferred.)
Tell students that they are going to design a spreadsheet to encode using the Caesar cypher.
Having students develop their own Caesar code spreadsheet introduces a number of the key features of spreadsheet formulas.
Students create their own Caesar Code encryption/decryption spreadsheet as follows:
Demonstrate the online wartime Enigma machine at the Enigma simulation site and have students try using it.
Protecting sensitive data is vital.
Encryption of data is a means of protecting data, one example being the use of secret and public keys. We examine cryptography and modern encryption methods for transmitting digital data securely.
Explain that students will send coded messages to one another using the following two public-key simulation activities.
Explains modular arithmetic and in particular modular multiplication tables.
Distribute the worksheet Caesar code activities (XLS) and conduct Activity 1.
First work through an example for students and answer any questions.
M9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
2 | 0 | 2 | 4 | 6 | 8 | 1 | 3 | 5 | 7 |
3 | 0 | 3 | 6 | 0 | 3 | 6 | 0 | 3 | 6 |
4 | 0 | 4 | 8 | 3 | 7 | 2 | 6 | 1 | 5 |
5 | 0 | 5 | 1 | 6 | 2 | 7 | 3 | 8 | 4 |
6 | 0 | 6 | 3 | 0 | 6 | 3 | 0 | 6 | 3 |
7 | 0 | 7 | 5 | 3 | 1 | 8 | 6 | 4 | 2 |
8 | 0 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |
Distribute the worksheet Cryptography: Public-key encryption activity 2.
First work through an example for students and answer any questions. Refer to a sample completed solution.
Students next encrypt, transmit and decrypt a three-letter word without the use of a table using a method which generates valid modular numbers. The steps are outlined on the worksheet.
Students discuss what they have learnt about the limitations of public/private key encryption. It may be useful to capture this in the form of an infographic, table or resume notes. There is an opportunity here to develop some peer teaching strategies where learners are asked to teach each other some core elements form the learning sequence to clarify any misconceptions and deepen understanding.