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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
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
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Seitenzahl: 395
Veröffentlichungsjahr: 2020
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Table of Contents
Cover
Introduction
What This Book Covers
What You Need to Know
What You Need to Have
How to Use This Book
What's on the Website
CHAPTER 1: Introduction to Cryptography and Python
Exploring Algorithms
Why Use Python?
Downloading and Installing Python
Testing Your Install
Diving into Python Basics
Creating a Reverse Cipher
Summary
CHAPTER 2: Cryptographic Protocols and Perfect Secrecy
The Study of Cryptology
Attack Models
Shannon's Theorem
One-Time Pad
One-Way Hashes
Perfect Forward Secrecy
Published and Proprietary Encryption Algorithms
Summary
References
CHAPTER 3: Classical Cryptography
Password Best Practices
Obfuscating Data
Historical Ciphers
Summary
CHAPTER 4: Cryptographic Math and Frequency Analysis
Modular Arithmetic and the Greatest Common Devisor
Prime Numbers
Basic Group Theory
Modular Inverses
Extending the GCD
Euler's Theorem
Pseudorandomness
Solving Systems of Linear Equations
Frequency Analysis
Cryptanalysis with Python
Summary
CHAPTER 5: Stream Ciphers and Block Ciphers
Convert between Hexdigest and Plaintext
Use Stream Ciphers
Use Block Ciphers
Summary
CHAPTER 6: Using Cryptography with Images
Simple Image Cryptography
Images and Cryptography Libraries
Image Cryptography
Steganography
Summary
CHAPTER 7: Message Integrity
Message Authentication Codes
Setting Up a Secure Channel
Summary
References
CHAPTER 8: Cryptographic Applications and PKI
The Public-Key Transformation
The El-Gamal Cryptosystem
Elliptic Curve Cryptography
Diffie-Hellman Key Exchange
Summary
CHAPTER 9: Mastering Cryptography Using Python
Constructing a Plaintext Communications Application
Installing and Testing Wireshark
Implementing PKI in the Application Using RSA Certificates
Implementing Diffie-Hellman Key Exchange
Wrapping Up
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1: Arithmetic Operators
Table 1.2: Arithmetic Operator Examples
Table 1.3: Comparison Operators
Table 1.4: Logical Operators
Table 1.5: Assignment Operators
Table 1.6: Bitwise Operators
Table 1.7: Membership Operators
Table 1.8: Identity Operators
Table 1.9: File Operations
Chapter 2
Table 2.1: Notation of Cryptographic Protocols
Table 2.2: Bitwise Operators
List of Illustrations
Chapter 1
Figure 1.1: Upgrading packages
Figure 1.2: Matplot.py test
Figure 1.3: Python installed successfully
Figure 1.4: Module methods
Chapter 2
Figure 2.1: Alice and Bob
Chapter 3
Figure 3.1: Column transposition table
Chapter 4
Figure 4.1:
Miller.py
test
Figure 4.2:
Generate_large_primes.py
Figure 4.3:
Euler.py
test
Figure 4.4:
EulerPlot.py
test
Figure 4.5:
FA.py
Figure 4.6:
Frequency.py
Figure 4.7:
declaration_freq.py
Figure 4.8:
Cearsar_FA.py
Figure 4.9:
online_example_fa.py
Figure 4.10:
Vigenere_break.py
Figure 4.11:
Vigenere_crypto.py
Chapter 5
Figure 5.1: Three-register representation of Trivium
Figure 5.2: ARC4 stream cipher
Figure 5.3: Python implementation of ChaCha20
Figure 5.4: ChaCha20Poly1305
Figure 5.5: ECB mode encryption
Figure 5.6: ECB mode decryption
Figure 5.7: Cipher Block Chaining (CBC) mode encryption
Figure 5.8: Cipher Block Chaining (CBC) mode decryption
Figure 5.9: Cipher Feedback (CFB) mode encryption
Figure 5.10: CFB mode decryption
Figure 5.11: Output Feedback (OFB) mode encryption
Figure 5.12: Output Feedback (OFB) mode decryption
Figure 5.13: Counter (CTR) mode encryption
Figure 5.14:
Counter (CTR) mode decryption
Figure 5.15: Feistel Network encryption
Figure 5.16: Feistel Network decryption
Chapter 6
Figure 6.1: Original
ch6_secret_image.jpg
file
Figure 6.2: Error message for
e_ch6_secret_image.jpg
Figure 6.3: Side by side of
ch6_secret_image.jpg
and
d_ch6_secret_image.jpg
...
Figure 6.4: Cryptography library test
Figure 6.5: Python output for Fernet
Figure 6.6: Image encryption modes
Figure 6.7: Plane image in BMP format
Figure 6.8: ECB encrypted plane
Figure 6.9: ECB decrypted plane
Figure 6.10: ECB security issue
Figure 6.11: CBC encrypted plane
Figure 6.12: Steganography example
Figure 6.13: High-definition photo of dogs
Figure 6.14: Steganography with media
Figure 6.15: FITS Files
Chapter 7
Figure 7.1: Binary digests
Figure 7.2: CBC-MAC example
Figure 7.3: Output of
Server.py
Figure 7.4: Messages entered here will be sent unencrypted to the server.
Figure 7.5:
server.py
Figure 7.6:
client.py
Figure 7.7: Secured communications
Figure 7.8: Message and MAC server
Figure 7.9: Message and MAC client
Chapter 8
Figure 8.1: Understanding RSA
Figure 8.2: Generating RSA certs
Figure 8.3: RSA decrypt
Figure 8.4: Output for the RSA BLOB program
Figure 8.5: ElGamal key
Figure 8.6: An elliptic curve
Figure 8.7: Point intersection of ECC curve
Figure 8.8: Diffie-Hellman exchange example
Chapter 9
Figure 9.1: Plaintext messaging
Figure 9.2: Wireshark overview
Figure 9.3: Wireshark traffic
Figure 9.4: PKI overview
Figure 9.5: PKI Encryption enabled
Figure 9.6: Wireshark output
Figure 9.7:
json
module
Figure 9.8: Final version
Figure 9.9: Diffie-Hellman Exchange chat
Figure 9.10: Shared key not passed
Guide
Cover
Table of Contents
Begin Reading
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Implementing Cryptography Using Python®
Shannon W. Bray
Introduction
I initiated my journey into cryptography while studying for my undergrad. Most of the cryptography concepts I learned were based on what one would need for their CISSP or Security+ exams. Most of my understanding was at a high level, and it was difficult to remember the more intricate aspects until cryptography became a primary focus.
It wasn't until I started my master's in cybersecurity that I began applying cryptographic features within a scripting environment. The concepts in this book will help you advance your knowledge and experience as you dig deeper into understanding the use of cryptography in Python.
Over the past few years, several governments have discussed legislation that will ensure that any form of communication, whether it's an email, text message, or video chat, can always be read by the police or intelligence services if they have a warrant. Governments are putting pressure on technology companies to give them backdoor access or the keys to the kingdom so that they can keep the country safe.
The fight between lawmakers and encrypted messaging platforms has entered new territory. Imagine a world where the government has seized the opportunity to scan every electronic message by government-approved scanning software. The privacy and security of all users will suffer if law enforcement agencies achieve their dream of breaking cryptosystems. Proponents of end-to-end encryption, like Microsoft, Facebook, and Google, may lose their campaign to maintain user security as a priority.
We have all heard of times when it would be beneficial for encrypted data to magically become readable; this is often related to criminal cases. Should criminals be allowed to plot their plans in secret? Where does the right to our privacy start? In reality, there are technical and legal issues with allowing governments to do this; this of course will be strongly opposed by technology and privacy advocates. The world is at war on what can be encrypted, what should be encrypted, and who should have the keys to unlock someone else's encryption.
Whether you agree or disagree with what powers a nation-state should have over encrypted communications in their country, you should understand what encryption is, how to apply it when needed, and how to ensure that the data you are receiving is authentic and confidential. Over the course of this book, you will get a basic understanding of how to cryptographically secure your messages, files, or Internet traffic using easy-to-understand Python recipes that have been created or updated to support Python 3.
What This Book Covers
This book focuses on helping you pick the right Python environment for your needs so that you can hit the ground running. You will get an understanding of what algorithms are and explore the basics of Python.
Once you have an idea of where you are starting from, you will get an overview of what cryptography is, what perfect secrecy means, and the history of cryptography and how its use changed our world.
To get a full understanding of some of the cryptographic concepts, a little math is needed. You will get an understanding of how prime numbers, basic group theory, and pseudorandom number generators help build cryptographic solutions. This will build the foundation for understanding various stream and block ciphers and highlight some of their encryption modes and weaknesses.
Every cryptographic discussion is better with pictures, so we will spend a chapter focusing on how image cryptography and steganography work. We'll also highlight a few issues that you will need to be aware of while dealing with images.
Message integrity is just as important as message secrecy. Knowing who sent the message to you directly relates to whether the message is credible. You will learn how to generate message authentication codes to ensure integrity during transit.
The strength of encryption will be shown at the end of the book when you will learn about PKI schemes and explore how to implement elliptic curve cryptography in an application. The application you build will exchange data in a highly secure format over an unsecure channel, thus ensuring that you are able to control your own end-to-end encryption scheme that no one will be able to decrypt without the keys you create. I hope you find the journey as fun as I did.
What You Need to Know
This book assumes that you are fairly new to cryptography. While there is a brief introduction to how to set up and use Python, you will get the most out of the book if you have experience in another programming or scripting language.
What You Need to Have
The concepts presented in this book can be executed on Microsoft Windows, Linux, Chromebook, or iOS. Your choice of editor will most likely depend on the underlying operating system, although most of the Python recipes presented here will execute in online editors as well as most shells that are using a Python interpreter that is 3.0 or greater.
How to Use This Book
The topics in this book get more advanced as you progress through it, so you can work through the material from front to back and build your skills as you go. You can also use this book as a reference that you can consult when you need help with the following situations:
You're stuck while trying to figure out how to secure your data.
You need to do something using cryptography that you've never done before.
You have some time on your hands, and you're interested in learning something new about Python and cryptography.
The index is comprehensive, and each chapter typically focuses on a single broad topic. Don't be discouraged if some of the material is over your head. As you work through the coding samples and build out the final solution, the concepts should become easier to understand.
What's on the Website
Nearly everything discussed in this book has examples with it. You can (and should) download the many useful examples included with this book. We have verified that each file will run in environments that are Python version 3.0 and higher.
The files are located at github.com/braycrypto/cryptography, as well as at www.wiley.com/go/cryptographywithpython.
