Free ebook on practical cryptography for developers: encryption, password security, key management, sessions, and secure application design.
Free ebook + audiobook content
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Threat Models, Entropy, and Attacker Capabilities
+ Exercise: Why does a threat model change how much entropy a secret needs? 18 minutes
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Safe Symmetric Encryption in Real Applications
+ Exercise: Which approach best reduces the risk of ciphertext being replayed or transplanted into a different context while still using symmetric encryption safely? 19 minutes
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Hashing, Password Storage, and Credential Abuse Defenses
+ Exercise: Which approach best reduces the impact if an attacker steals only your user database but not your application servers? 21 minutes
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Public-Key Cryptography Choices and Key Management
+ Exercise: Why do most modern protocols use public-key cryptography only to bootstrap a session and then switch to symmetric cryptography for bulk data? 22 minutes
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Secure Communication Patterns Beyond the Happy Path
+ Exercise: A service receives signed webhooks and must handle legitimate retries without allowing malicious replays. Which approach best achieves this? 23 minutes
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Token, Session, and Cookie Security in Real Systems
+ Exercise: Which approach best reduces the impact of a stolen refresh token in a system that uses access and refresh tokens? 19 minutes
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End-to-End Encryption Design Patterns and Tradeoffs
+ Exercise: Why do some group E2EE systems use per-sender sender keys instead of encrypting each message separately for every recipient device? 21 minutes
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Secure Architecture Checklists for Web, Mobile, and Backend
+ Exercise: Which approach best keeps a secure architecture checklist from slowing delivery while still making security verifiable? 22 minutes
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Failure Cases: How Crypto Breaks in Production
+ Exercise: Which change best reduces the risk of signature bypass when different services interpret the same JSON differently? 21 minutes
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Implementation Labs: Library-First Patterns and Secure Defaults
+ Exercise: Which design choice best supports secure algorithm upgrades without letting callers choose weaker crypto options? 23 minutes
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Capstone: Secure Authentication and Data Protection for a Small SaaS
+ Exercise: Which design best reduces blast radius when adding application-level encryption for sensitive SaaS data? 18 minutes
About the free ebook with audio
Practical Cryptography for Developers: Build, Break, and Secure Real Systems
This free ebook helps developers apply cryptography safely in web, mobile, and backend systems. Rather than treating cryptography as a collection of algorithms, it focuses on the engineering decisions that determine whether security holds up in production.
Design for realistic attackers
Learn to define threat models, assess attacker capabilities, and make informed choices about entropy, keys, encryption, authentication, and secure communication. The material explains why secure defaults and well-maintained libraries are usually safer than custom cryptographic code.
Protect data and identities
Explore practical patterns for symmetric encryption, password hashing, public-key cryptography, key management, tokens, sessions, and cookies. You will see how credential abuse, weak storage practices, missing integrity checks, and poor lifecycle controls can undermine otherwise sound designs.
Handle real-world failure paths
Security systems must remain reliable beyond the happy path. This ebook examines end-to-end encryption tradeoffs, communication failures, production crypto mistakes, and architecture checks for applications that process sensitive data.
What you will be able to do
- Choose encryption and hashing approaches appropriate to application requirements.
- Use library-first implementation patterns and secure defaults.
- Recognize common key, token, session, and password-handling failures.
- Review web, mobile, and backend designs with practical security checklists.
- Apply the concepts in a small SaaS authentication and data-protection capstone.
Important: effective cryptography depends on correct implementation, key handling, protocol design, and operational controls—not just selecting a strong algorithm.
How should developers store passwords securely?
Use a dedicated password-hashing function with unique salts and tuned work factors; never store reversible encrypted passwords.
Why is key management as important as encryption?
Strong encryption fails when keys are exposed, reused improperly, stored insecurely, or not rotated and revoked.
What are common cryptography mistakes in web applications?
Common failures include weak randomness, custom crypto, insecure token storage, missing integrity protection, and poor session controls.
This ebook/audiobook includes:
3 hours and 53 minutes of audio content
Digital certificate of course completion (Free)
Exercises to train your knowledge
100% free, from content to certificate
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