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Encryption: Caesar & Vernam Ciphers

AQA 75174.5.6A-levelLesson packSubscription
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4.5.6.10 Encryption — define encryption and the terms cipher, plaintext and ciphertext. Encrypt and decrypt using the Caesar cipher and explain why it is easily cracked. Encrypt and decrypt using the Vernam cipher (one-time pad) via XOR, and explain why it has perfect security compared with ciphe…

19 slides.

Lesson outline

  1. Retrieval Starter — ASCII, Binary & XOR
  2. Keyword Glossary
  3. Check: Plaintext or Ciphertext?
  4. What Is Encryption?
  5. The Caesar Cipher: Shifting the Alphabet
  6. Quick Check — Apply the Shift
  7. Worked Example — Encrypting with Caesar
  8. Practice — Caesar Encrypt & Decrypt
  9. Why the Caesar Cipher Is Easily Cracked
  10. Hinge Check — What's the Mistake?
  11. The Vernam Cipher & the One-Time Pad
  12. Worked Example — Vernam XOR Encryption
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