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Unit 2: Cryptography

About this unit

How have humans protected their secret messages through history? What has changed today?

Ancient cryptography

Explore how we have hidden secret messages through history.

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Ciphers

Assess your understanding of the code breaking presented in the ancient cryptography lesson. This series of articles and exercises will prepare you for the upcoming challenge!

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Practice

Cryptography challenge 101

Ready to try your hand at real-world code breaking? This adventure contains a beginner, intermediate and super-advanced level. See how far you can go!

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Practice

Modern cryptography

A new problem emerges in the 20th century. What happens if Alice and Bob can never meet to share a key in the first place?

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Modular arithmetic

This is a system of arithmetic for integers. These lessons provide a foundation for the mathematics presented in the Modern Cryptography tutorial.

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Practice

Primality test

Why do primes make some problems fundamentally hard? To find out we need to explore primality tests in more detail.

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Randomized algorithms

Would access to coin flips speed up a primality test? How would this work?

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