Module: Digital Encryption "Crash Course"

A nod to the mathematicians: The power of prime numbers

Many sensitive transactions in the 21st century are enabled by digital security systems which allow parties to communicate over open channels in a private way. This process involves using clevery mathematical agorithms to encrypt messages whose meaning can only be extracted with carefully controlled "keys" held by communicating parties.

This module will explore these mechanisms and test them using a "spy"-like activity.

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check_boxLearning Objectives
motorcycleExercise 1: Encryption Basics: Don't be afraid of math
motorcycleExercise 2: Hide and "go seek" for the computer student
motorcycleExercise 3: Exploring Internet security

Learning Objectives


Explain in very general terms how prime factorization forms the basis of "trap-door"/one-way algoritms.


Use free, online encryption packages to encrypt and decrypt messages to a partner--securely.


Employ basic knowledge of encryption to verify the security of an internet site whose security matters to you.



External Resources

These online tools and references guide us through our learning about encryption

This post by a geek explains the basics of the math behind the RSA encryption algorithms. This is best for readers who want to dig into encryption.

Math u Code provides Java implementations of essential encryption algorithms.

This slide show by an academic named Kalyan Chakraborty in Nepal provides solid diagrams and explanations of the encryption process and is a starting point for learning about internet security.

iGolder encrypted communication tools offer free online utilities for generating public and private keys as well tools for encrypting and decrypting messages using those keys to third parties.

A techie named Nathan has created a demo site for generating and using public/private key pairs and conducting basic encryption using those keys. This is NOT A SECURE site since it's for demonstration purposes only.

Free technical references on encryption exist in case you're interested in the math behind encryption. It's all "open source!"



Exercise 1: Notes on the basis of encryption

Exercise type: Note-based discussion

Learn about the fundamentals of internet security.



Exercise 2: Hide and "Go seek" for the computer student

You'll never see this childhood game the same

Public key and cyphertext Google Doc

Activity steps as follows:

  1. Pick a partner
  2. Together, create a public and private key.
  3. Post the public key on our public google doc
  4. The searching partner should save the private key in a secure place
  5. The hiding partner should go find a hiding spot (generate a secret) and return to the room. Encode the location using your partner's public key. Post the cyphertext in our public sharing place
  6. The hiding partner goes and hides with a secrecy token
  7. The seeking partner decrypts the finding instructions and then "goes and seeks" the hiding partner.
  8. Obtain the secrecy token from the hiding partner and provide it to the verifying entity.



Exercise 3: Explore internet certificates

Visit some HTTPS sites to examine the certificates used for secure browsing.