Computer Science Principles Unit 4 Chapter 1 Lesson 9: Public Key Cryptography

This is a big multi-part lesson that introduces the concept of public key cryptography which is an answer to the crucial question: How can two people send encrypted messages back and forth over insecure channels (the Internet) without meeting ahead of time to agree on a secret key? In a nutshell, there are two main principles we want students to understand:

1. The mechanics of communication with public key cryptography
2. The basic mathematical principles that make it possible

The lesson gets at these two core ideas through a deliberate chain of thought experiments, demonstrations, activities, and widgets. All parts are building blocks that lead to a deeper understanding of how it works.

Students will be able to:
- explain what the modulo operation does and how it operates as a "one-way" function.
- follow an asymmetric encryption algorithm to encrypt a numerical message using the Public Key Crypto widget.
- explain the difference between symmetric and asymmetric encryption.
- describe the basic process of encrypting data using public key encryption.
- explain the benefits of public key cryptography.

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