110: codes and ciphers: the history of cryptography (ks5)
Investigate the history of cryptography, from Caesar ciphers and Alan Turing's Enigma to modern asymmetric encryption.
The Imitation Game: From Caesar to RSA
The Scenario
The National Museum of Computing is curating a new exhibit titled "Secrets & Spies: The Evolution of Digital Defence". As a specialist historian, you have been commissioned to produce a technical briefing document that explains three critical turning points in cryptographic history. The museum needs accurate technical details, not just stories.
The Persona
The Historian investigates key milestones, pioneering figures, and technological breakthroughs. You understand that to innovate for the future, you must appreciate the foundations of the past. You trace the evolution of concepts like encryption from their primitive origins to modern implementation.
The National Museum of Computing is curating a new exhibit titled "Secrets & Spies: The Evolution of Digital Defence". As a specialist historian, you have been commissioned to produce a technical briefing document that explains three critical turning points in cryptographic history. The museum needs accurate technical details, not just stories.
The Historian investigates key milestones, pioneering figures, and technological breakthroughs. You understand that to innovate for the future, you must appreciate the foundations of the past. You trace the evolution of concepts like encryption from their primitive origins to modern implementation.
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Part 1: The Classical Era (Substitution)
Open a word processor to start your Technical Briefing.
Research the Caesar CipherI have no idea what this means and the Vigenère CipherI have no idea what this means.
In your document, explain the concept of a Substitution Cipher.
Analysis: Explain why a standard Caesar cipher is computationally easy to break using Frequency Analysis.
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Part 2: The Mechanical Era (Enigma)
Use an online Enigma simulator (search for "Enigma machine simulator") to encrypt a short message.
Research the role of Alan TuringI have no idea what this means and Bletchley Park.
Explain the concept of Polyalphabetic Substitution used by the Enigma machine.
Key Question: How did the Enigma machine change the cipher alphabet after every key press? Explain the role of the RotorsI have no idea what this means.
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Part 3: The Modern Era (Asymmetric)
Research the difference between Symmetric EncryptionI have no idea what this means (Private Key) and Asymmetric EncryptionI have no idea what this means (Public Key).
Investigate how HTTPSI have no idea what this means uses these technologies today.
Create a comparison table in your document.
Evaluation: Why was the invention of Asymmetric encryption (Diffie-Hellman/RSA) necessary for the internet to function? (Hint: Search for "The Key Exchange Problem").
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Submission
Ensure your document has clear headings for each era.
Check your technical terminology is accurate.
Upload your document to the class submission folder.
Outcome
A technical explanation of why Frequency Analysis breaks simple ciphers.
An accurate description of the Enigma machine's mechanical logic.
A comparison of Symmetric vs Asymmetric encryption.
Correct use of terminology: PlaintextI have no idea what this means, CiphertextI have no idea what this means, KeyI have no idea what this means, AlgorithmA 'recipe' or sequence of 'unambiguous' instructions for solving a problem..
Last modified: December 15th, 2025
