ACARA 9-10 Digital Technologies: Encryption and classical ciphers
Students learn how encryption works and practise encrypting, decrypting and breaking Caesar, substitution, rail fence and Vigenere ciphers by hand.
One content description (AC9TDI10K01) from the full ACARA Digital Technologies Years 9–10 — Cyber Security Threats and Vulnerabilities journey. All 19 modules below are in that journey too, with the same content — add just these to a class, or the whole strand.
Modules (19)
1
Why data is encrypted
2
Encryption and decryption
3
Plaintext
4
Ciphertext
5
Encryption key
6
Encrypting a message with a Caesar shift
7
Wrapping around from Z to A
8
Decrypting a message with a Caesar shift
9
Using a cipher wheel or strip
10
Caesar cipher wrap-around with MOD 26
11
Key space: how many keys a cipher has
12
Breaking a Caesar cipher by trying every shift
13
Monoalphabetic substitution cipher
14
Frequency analysis
15
Building a frequency table with COUNTIF
16
Transposition cipher: rail fence
17
Polyalphabetic ciphers
18
Vigenere cipher
19
Why a Caesar cipher is weak compared with modern encryption
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