The Joy of Cryptography

Contents
1. Unconditional Cryptography
  
  One-Time Pad & the Provable Security Mindset
  
  Rudiments of Provable Security
  
  ☆ Secret Sharing
2. Pseudorandomness
  
  Modern Computational Cryptography
  
  Pseudorandom Generators
  
  Pseudorandom Functions
  
  Pseudorandom Permutations
3. Symmetric-Key Encryption
  
  Chosen-Plaintext Attacks Against Encryption
  
  Chosen-Ciphertext Attacks Against Encryption
4. Hashing
  
  Collision-Resistant Hash Functions
  
  ☆ Universal Hash Functions
  
  Random Oracles and Other Idealized Models
5. Asymmetric-Key Cryptography
  
  Key Exchange
  
  Public-Key Encryption
  
  RSA
  
  Digital Signatures
6. Advanced Topics
  
  Encrypted Messaging & Ratcheting
  
  Authenticated Key Exchange
  
  Zero-Knowledge Proofs
  
  Post-Quantum Cryptography
7. Appendix
  
  Math Review
  
  Binary Finite Fields
  
  Bibliography
About

17

Advanced Topics

Encrypted Messaging and Ratcheting

Chapter Contents

Chapter Contents

17.1.Forward secrecy and the symmetric ratchet
17.2.Post-compromise secrecy and the asymmetric ratchet
17.3.The double ratchet and the Signal protocol
17.4.Group messaging and MLS
17.4.1.Updatable PKE
Exercises
Chapter Notes & References

Previous Chapter16. Digital Signatures
Next Chapter18. Authenticated Key Exchange

This chapter will become available online in July 2026.

Previous Chapter16. Digital Signatures
Next Chapter18. Authenticated Key Exchange

The Joy of Cryptography

An undergraduate-level textbook that introduces students to the fundamentals of provable security.

About this Book

Acknowledgements

This book is possible with support from the National Science Foundation and the Open Textbook Initiative at Oregon State University.

Unconditional Cryptography
Pseudorandomness
Symmetric-Key Encryption
1. Chosen-Plaintext Attacks Against Encryption
2. Chosen-Ciphertext Attacks Against Encryption
Hashing
Asymmetric-Key Cryptography
Advanced Topics
Appendix

The Joy of Cryptography is by Mike Rosulek and made available under Creative Commons CC-BY-ND-NC license.

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