© 2019

Practical Cryptography in Python

Learning Correct Cryptography by Example

  • Teaches you the basics of writing Python programs that use cryptography

  • Offers clear guidance on the correct use of cryptography in a landscape where good advice is hard to come by

  • Provides examples of bad cryptography along with source code that breaks it


Table of contents

  1. Front Matter
    Pages i-xv
  2. Seth James Nielson, Christopher K. Monson
    Pages 1-19
  3. Seth James Nielson, Christopher K. Monson
    Pages 21-52
  4. Seth James Nielson, Christopher K. Monson
    Pages 53-110
  5. Seth James Nielson, Christopher K. Monson
    Pages 111-163
  6. Seth James Nielson, Christopher K. Monson
    Pages 165-212
  7. Seth James Nielson, Christopher K. Monson
    Pages 213-248
  8. Seth James Nielson, Christopher K. Monson
    Pages 249-292
  9. Seth James Nielson, Christopher K. Monson
    Pages 293-359
  10. Back Matter
    Pages 361-371

About this book


Develop a greater intuition for the proper use of cryptography. This book teaches the basics of writing cryptographic algorithms in Python, demystifies cryptographic internals, and demonstrates common ways cryptography is used incorrectly.

Cryptography is the life blood of the digital world’s security infrastructure. From governments around the world to the average consumer, most communications are protected in some form or another by cryptography. These days, even Google searches are encrypted. Despite its ubiquity, cryptography is easy to misconfigure, misuse, and misunderstand.

Developers building cryptographic operations into their applications are not typically experts in the subject, and may not fully grasp the implication of different algorithms, modes, and other parameters. The concepts in this book are largely taught by example, including incorrect uses of cryptography and how "bad" cryptography can be broken. By digging into the guts of cryptography, you can experience what works, what doesn't, and why.

What You’ll Learn:

  • Understand where cryptography is used, why, and how it gets misused
  • Know what secure hashing is used for and its basic properties
  • Get up to speed on algorithms and modes for block ciphers such as AES, and see how bad configurations break
  • Use message integrity and/or digital signatures to protect messages
  • Utilize modern symmetric ciphers such as AES-GCM and CHACHA
  • Practice the basics of public key cryptography, including ECDSA signatures
  • Discover how RSA encryption can be broken if insecure padding is used
  • Employ TLS connections for secure communications
  • Find out how certificates work and modern improvements such as certificate pinning and certificate transparency (CT) logs


Cryptography Python Encryption Authentication Message integrity Hashing Digital signatures TLS Public key cryptography Certificates Security

Authors and affiliations

  1. 1.AustinUSA
  2. 2.HampsteadUSA

About the authors

Dr. Seth James Nielson is the founder and chief scientist of Crimson Vista, Inc., a boutique computer security research and consulting company. He is also an adjunct professor at Johns Hopkins University where he teaches network security and has also served as the director of advanced research projects at the Information Security Institute. As part of his Hopkins work, he co-founded the knowledge base, through a generous grant from Cisco. 

Christopher K. Monson has a PhD in machine learning, and has spent over a decade at Google in various engineering, machine learning, and leadership roles. He has broad experience writing and teaching programming courses in multiple languages, and has worked in document password recovery, malware detection, and large-scale secure computing. He is currently serving as the chief technology officer at Data Machines Corp. and teaches cloud computing security as a lecturer at the Johns Hopkins University Information Security Institute.

Bibliographic information

  • Book Title Practical Cryptography in Python
  • Book Subtitle Learning Correct Cryptography by Example
  • Authors Seth James Nielson
    Christopher K. Monson
  • DOI
  • Copyright Information Seth James Nielson, Christopher K. Monson 2019
  • Publisher Name Apress, Berkeley, CA
  • eBook Packages Professional and Applied Computing Professional and Applied Computing (R0) Apress Access Books
  • Softcover ISBN 978-1-4842-4899-7
  • eBook ISBN 978-1-4842-4900-0
  • Edition Number 1
  • Number of Pages XV, 371
  • Number of Illustrations 39 b/w illustrations, 0 illustrations in colour
  • Topics Security