Implementing Cryptography Using Python®

**Learn to deploy proven cryptographic tools in your applications and services** Cryptography is, quite simply, what makes security and privacy in the digital world possible. Tech professionals, including programmers, IT admins, and security analysts, need to understand how cryptography works to protect users, data, and assets. __Implementing Cryptography Using Python__ will teach you the essentials, so you can apply proven cryptographic tools to secure your applications and systems. Because this book uses Python, an easily accessible language that has become one of the standards for cryptography implementation, you’ll be able to quickly learn how to secure applications and data of all kinds. In this easy-to-read guide, well-known cybersecurity expert Shannon Bray walks you through creating secure communications in public channels using public-key cryptography. You’ll also explore methods of authenticating messages to ensure that they haven’t been tampered with in transit. Finally, you’ll learn how to use digital signatures to let others verify the messages sent through your services. * Learn how to implement proven cryptographic tools, using easy-to-understand examples written in Python * Discover the history of cryptography and understand its critical importance in today’s digital communication systems * Work through real-world examples to understand the pros and cons of various authentication methods * Protect your end-users and ensure that your applications and systems are using up-to-date cryptography Cover Title Page Copyright Page About the Author Acknowledgments Contents at a Glance Contents Introduction Chapter 1 Introduction to Cryptography and Python Exploring Algorithms Why Use Python? Downloading and Installing Python Installing on Ubuntu Installing on macOS Installing on Windows Installing on a Chromebook Installing Additional Packages Installing Pip, NumPy, and Matplotlib Installing the Cryptography Package Installing Additional Packages Testing Your Install Diving into Python Basics Using Variables Using Strings Introducing Operators Understanding Arithmetic Operators Understanding Comparison Operators Understanding Logical Operators Understanding Assignment Operators Understanding Bitwise Operators Understanding Membership Operators Understanding Identity Operators Using Conditionals Using Loops for while continue break else Using Files Understanding Python Semantics Sequence Types Introducing Custom Functions Downloading Files Using Python Introducing Python Modules Creating a Reverse Cipher Summary Chapter 2 Cryptographic Protocols and Perfect Secrecy The Study of Cryptology Understanding Cryptography Cryptography’s Famous Family: Alice and Bob Diffie-Hellman Data Origin Authentication Entity Authentication Symmetric Algorithms Asymmetric Algorithms The Needham-Schroeder Protocols The Otway-Rees Protocol Kerberos Multiple-Domain Kerberos X.509 Formal Validation of Cryptographic Protocols Configuring Your First Cryptographic Library Understanding Cryptanalysis Brute-Force Attacks Side-Channel Attacks Social Engineering Analytical Attacks Frequency Analysis Attack Models Shannon’s Theorem One-Time Pad XOR, AND, and OR One-Time Pad Function One-Way Hashes Cryptographic One-Way Hashes Message Authentication Codes Perfect Forward Secrecy Published and Proprietary Encryption Algorithms Summary References Chapter 3 Classical Cryptography Password Best Practices Password Storage Hashing Passwords Salting Passwords Stretching Passwords Password Tools Obfuscating Data ASCII Encoding Base64 Encoding Text Binary Data Decoding Historical Ciphers Scytale of Sparta Substitution Ciphers Caesar Cipher ROT-13 Atbash Cipher Vigenère Cipher Playfair Hill 2x2 Column Transposition Affine Cipher Summary Chapter 4 Cryptographic Math and Frequency Analysis Modular Arithmetic and the Greatest Common Devisor Prime Numbers Prime Number Theorem School Primality Test Fermat’s Little Theorem Miller-Rabin Primality Test Generate Large Prime Numbers Basic Group Theory Orders of Elements Modular Inverses Fermat’s Little Theorem to Find the Inverse Extending the GCD Euler’s Theorem Pseudorandomness Breaking C’s rand() Function Solving Systems of Linear Equations Frequency Analysis Cryptanalysis with Python Using an Online Word List Determining the Frequency Breaking the Vigenère Cipher Summary Chapter 5 Stream Ciphers and Block Ciphers Convert between Hexdigest and Plaintext Use Stream Ciphers ARC4 Vernam Cipher Salsa20 Cipher ChaCha Cipher Use Block Ciphers Block Modes of Operations ECB Mode CBC Mode CFB Mode OFB Mode CTR Mode Tricks with Stream Modes DIY Block Cipher Using Feistel Networks Advanced Encryption Standard (AES) Using AES with Python File Encryption Using AES File Decryption Using AES Summary Chapter 6 Using Cryptography with Images Simple Image Cryptography Images and Cryptography Libraries Understanding the Cryptography Library Understanding the Cryptosteganography Library Image Cryptography File Cryptography Using Fernet Image Cryptography Using Fernet AES and Block Modes of Operations Exploring a Simple ECB Mode Example Exploring a Simple CBC Mode Example Applying the Examples Steganography Storing a Message Inside an Image Storing a Binary File Inside an Image Working with large images Summary Chapter 7 Message Integrity Message Authentication Codes Hash-based Message Authentication Code Using HMAC to Sign Message Message Digest with SHA Binary Digests NIST Compliance CBC-MAC Birthday Attacks Crafting Forgeries The Length Extension Attack Setting Up a Secure Channel Communication Channels Sending Secure Messages Over IP Networks Create a Server Socket Create a Client Socket Create a Threaded Server with TCP Adding Symmetric Encryption Concatenate Message and MAC Summary References Chapter 8 Cryptographic Applications and PKI The Public-Key Transformation Exploring the Basics of RSA Generating RSA Certificates Constructing Simple Text Encryption and Decryption with RSA Certificates Constructing BLOB Encryption and Decryption with RSA Certificates The El-Gamal Cryptosystem Elliptic Curve Cryptography Generating ECC Keys Key Lengths and Curves Diffie-Hellman Key Exchange Summary Chapter 9 Mastering Cryptography Using Python Constructing a Plaintext Communications Application Creating a Server Creating the Client Creating the Helper File Execution Installing and Testing Wireshark Implementing PKI in the Application Using RSA Certificates Modifying the Server Modifying the Client Modifying the Helper File Execution Implementing Diffie-Hellman Key Exchange Modifying the Server File Modifying the Client File Modifying the Helper File Creating the Diffie-Hellman Class File Execution Wrapping Up Index EULA This Book Is Designed To Teach Students How To Analyze And Deploy Cryptography In The Real World. The Reader Will Learn The History Of Cryptography And How To Break Several Historical Cyphers Using Python. The Reader Will Then Learn Additional Methods That Are Strong Enough To Withstand Real Attacks. The Book Will Teach The Reader How To Create Secure Communications In Public Channels Using Public-key Cryptography. The Reader Will Explore Methods Of Authenticating Messages To Ensure That They Haven't Been Tampered With In Transit. They Will Then Explore The Use Of Digital Signatures That Lets Others Verify That Messages Were Sent By An Individual.