Ciphers and Cybersecurity in Other Fields

Cybersecurity First Principles in this lesson

Data Hiding: Data hiding is the technique that does not allow certain aspects of an object to be observed or accessed. Data and information hiding keeps the programmer from having complete access to data structures. It allows access to only what is necessary.
Layering: Cyber security uses multiple layers of defense or protecting information. If one layer is defeated the next layer should catch it.
Least Privilege: One of the ways to protect information is by limiting what people can see and do with your information and resources. The principle of least privilege says to allow the minimum number of privileges necessary to accomplish the task.
Pre-digital era Ciphers: Transposition ciphers – rearrange the order of the characters of plaintext also called permutation ciphers The arrangement becomes the key Substitution ciphers – replace the characters with something else (e.g. another character or number) The replacement function becomes the key

Introduction

In this lesson, we will learn about ciphers and basic cryptography and how it can apply to cybersecurity and other areas of education. We will go over a brief history of the usage of ciphers and how they work.

Goals

By the end of this tutorial, you will be able to:

Understand and be able to describe data hiding, layering, and least privilege in terms of cryptography
Encrypt and decrypt simple messages using different Ciphers

Materials Required

Cipher Wheels
Vigenere Square

Prerequisite lessons

None

Basic Terms

Step 1: Learn all the words!

Plaintext/Cleartext - an unaltered message as it’s intended to be read

Ciphertext – message that has been changed so its meaning is concealed

Encryption/enciphering – changing plaintext to ciphertext

Decryption/deciphering – changing ciphertext back into plaintext

Key – secret value needed to encrypt and/or decrypt

Cryptographic Algorithm/cipher – a standard sequence of computational steps to encrypt or decrypt a message using a key

Cryptanalysis – practice of analyzing encrypted messages to reveal the plaintext without knowing the key

Strength – determines how much effort and how long it takes to break a ciphertext

Step 2: Ciphers

Zig-Zag and Route Crypto
Civil War Crypto Sticks
Caesar Ciphers
Vigenere Square
Enigma Machine

We will discuss the usages and history of each of these ciphers.

Step 3: Cryptanalysis

Frequency
By doing frequency analysis to see which letters appeared most often then substituting most frequent plain text letter, could break the cipher.
Language characteristics
If spaces are left in, then characteristics like single letter and 2 letter words are still in tact and knowledge of these can be utilized to help in breaking Having a longer message only makes both things easier to spot

Step 4: Practice decrypting and encrypting

Using the cipher rings we will practice encoding and decoding.

Self Exploration

Try some different encryption yourself.

Reflection

In this lesson, we saw how encryption can be used for data hiding. Multiple encryption rounds can also be used as for layering.

Additional Resources

For more information, investigate the following:

NSA Cytptochallenges - Puzzle of the week
NSA CryptoKids

Lead Author

Chris Daniels

Acknowledgements

Special thanks to Dr. Robin Gandhi for reviewing and editing earlier versions of this lesson.

License

Nebraska GenCyber
is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Lesson content: Copyright (C) Chris Daniels 2017.

This lesson is licensed by the author under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.