Codes, Ciphers, and Defence
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The impulse to hide information is as old as communication itself. Long before computers, people were developing systems to keep secrets, break enemy codes, and protect messages from prying eyes. Ancient Egyptians used non-standard hieroglyphs to obscure tomb inscriptions. Greek generals tattooed orders on shaved heads and waited for hair to grow back before sending the messenger. Julius Caesar shifted letters by three positions to encrypt military orders.
The tools have changed. The problem hasn’t.
Every time you see a padlock in your browser, you’re looking at the direct descendant of those ancient techniques. Modern encryption is mathematically more complex, but it runs on the same principle Caesar used: transform the message so only the intended recipient can read it.
This module traces that line — from wax tablets and cipher wheels to the algorithms protecting your bank transactions today. Understanding where encryption came from helps you understand why it matters, how it can break, and what it means when someone tells you a system is “secure.”
By the end, you’ll see how the same creative instinct that drove ancient code-makers drives modern security thinking — and why attackers and defenders have always been locked in the same arms race.