# Lesson Plan

| **Course:**    | Principles of Cybersecurity  |
| -------------- | ---------------------------- |
| **Lesson:**    | Introduction to Cryptography |
| **Intensity:** | Medium                       |
| **Duration:**  | 0.5 hours                    |

## LEARNING OBJECTIVES

* Name all key terms with their definition
* Recite one or more historical cryptographic ciphers
* Compare and contrast symmetric and asymmetric cryptography
* Explain the use of cryptographic hashing

## SUMMARY OF TASKS

### Important Definitions

* Define cryptography and cryptanalysis
* Define key terms
  * Cipher
  * Key
  * Plaintext
  * Ciphertext
  * Encrypt
  * Decrypt
* Discuss why we use cryptography today
  * Ensure confidentiality and integrity of our data

    **Origins of Cryptography**
* Discuss the history of cryptography
  * Started with transposition ciphers
    * Give example
    * Julius Caesar invented the 'Caesar Cipher'
  * Substitution cipher
    * Give example
  * The art of hiding in plain sight (steganography)
    * Ancient times a slave's head would be tattooed and concealed with the regrown hair
    * Others used invisible ink, microdots
  * Discuss the use of the Enigma during WWII
    * Alan Turing was one of the cryptanalysts and broke the Enigma

### Modern Cryptography

* Discuss using crypto for **confidentiality**
* Discuss modern crytography
  * Symmetric Cryptography (Secret Key)
    * Purpose: bulk data encryption
    * Key size: 64-512 bits
    * Key distribution: one key per com channel
    * Common algorithms: DES, AES, RC4
    * Discuss simple encryption example
  * Asymmetric Cyptography (Public-key)
    * Purpose: small data encryption and digital signing
    * Key size: 2048-4096 bits
    * Key distribution: one private, one public key
    * Common algorithms: RSA, DSA
    * Discuss simple encryption example
    * Discuss simple digital signature example
  * Discuss the problems with each
    * Symmetric - needs a key for each communication channel
    * Asymmetric - difficult to setup and needs significant infrastructure
  * Discuss using crypto for **integrity**
    * Discuss cryptographic hashing

## EVALUATION CRITERIA

Students will take a five question quiz for this module

## RESOURCES

[Crypto Corner - Transposition Ciphers](http://crypto.interactive-maths.com/simple-transposition-ciphers.html)\
[Crypto Corner - Caesar Shift Cipher](http://crypto.interactive-maths.com/caesar-shift-cipher.html)<br>

## REFERENCES

[Cryptography - Wikipedia](https://en.wikipedia.org/wiki/Cryptography)\
[Cryptanalysis - Wikipedia](https://en.wikipedia.org/wiki/Cryptanalysis)\
[The Enigma - Wikipedia](https://en.wikipedia.org/wiki/Enigma_machine)\
[Alan Turing - Wikipedia](https://en.wikipedia.org/wiki/Alan_Turing#Cryptanalysis)<br>
