Symmetric Cryptography Essential Training

Course details

If you work with computers, you use cryptography. Symmetric cryptography is a common method that uses the same key for encryption and decryption of data. Faster and less resource-intensive than asymmetric cryptography, symmetric cryptography is important for all IT professionals to understand. This course delivers a practical overview of the technology, emphasizing high-level concepts that affect how our data is stored and transmitted. Jeremy Hansen explains the difference between single key (symmetric) and multiple key (asymmetric) algorithms, and shows how symmetric encryption affects underlying binary data. Learn about the basic ciphers used in symmetric cryptography, including substitution, permutation, and transposition, and influential symmetric-key algorithms like the Advanced Encryption Standard and its predecessor, the Data Encryption Standard. Review modern block cipher modes like cipher block chaining (CBC), cipher feedback (CFB), and counter (CTR), which can help secure large amounts of data.

Learning objectives
Explain the role of encryption in modern security systems.
Explain the difference between one-key (symmetric) and multiple-key (asymmetric) algorithms.
Identify historical cryptographic algorithms.
Demonstrate the difference between block and stream ciphers.
Describe several methods that block ciphers use to encrypt and decrypt data.
Enumerate and describe several modern and recent block and stream cipher algorithms.

Concepts

Introduction

Cryptography is everywhere
Basic terminology
Intro to Codespaces

Symmetric Cryptography Overview

Cryptography's role
Kerckhoffs's principle
Symmetric keys
Block vs. stream ciphers
Cryptographic hash algorithms
Challenge - Building a hash algorithm
Solution - Building a hash algorithm

Representing and Manipulating Binary Data

Binary representation
Characters
Integers
Floating point numbers
Boolean operations
Padding
Challenge - QR code printer
Solution - QR code printer

Fundamental Algorithms and Components

Simple substitution ciphers
Polyalphabetic substitution ciphers
Permutation and transposition ciphers
Simple one-time pads with XOR
S-boxes and P-boxes
Feistel networks
Linear-feedback shift registers (LFSRs)
Challenge - Software-based LFSR
Solution - Software-based LFSR

Symmetric Algorithms

The Data Encryption Standard (DES)
The Advanced Encryption Standard (AES)
AES and DES in practice
The RC4 stream cipher
Challenge - Encrypting, decrypting, and hashing with OpenSSL
Solution - Encrypting, decrypting, and hashing with OpenSSL

Block Cipher Modes

Introduction to block cipher modes
Cipher block chaining (CBC)
CFB - Cipher feedback
OFB - Output feedback
CTR - Counter mode
Challenge - Building a block cipher with CBC mode
Solution - Building a block cipher with CBC mode

Keys and a Little Asymmetry

Exchanging keys
Key length and large numbers
The importance of randomness to cryptography
Modular arithmetic
Diffie Hellman key exchange
Challenge - Implementing Diffie Hellman
Solution - Implementing Diffie Hellman

Conclusion

Next steps