🔐 Cryptography
Based on 
Wikipedia, licensed CC BY-SA 4.0.
From XOR ciphers to TEE enclaves. Each chapter builds one layer of the modern security stack, with runnable code and diagrams.
| Chapter | |||
|---|---|---|---|
| 1. | Symmetric Ciphers | XOR, Caesar, substitution: encryption and decryption share the same secret | 🔐 |
| 2. | Block Ciphers | Feistel networks and AES: fixed-size blocks, multiple rounds, diffusion and confusion | 🔐 |
| 3. | Hash Functions | One-way compression: any input to a fixed-length fingerprint, no way back | 🔐 |
| 4. | MACs and Authentication | HMAC: a keyed hash that proves the message was not tampered with | 🔐 |
| 5. | Key Exchange | Diffie-Hellman: two strangers agree on a shared secret over a public channel | 🔐 |
| 6. | RSA | Public key encrypts, private key decrypts: the factoring problem makes it hard | 🔐 |
📺 Video lectures: Christof Paar: Introduction to Cryptography
Neighbors
- # Number Theory — RSA is Euler's theorem, key exchange is discrete logarithm
- 🔗 Abstract Algebra — elliptic curves are abelian groups
- 📡 Information Theory — Shannon's perfect secrecy is information-theoretic security
- 🔀 Theory of Computation — computational hardness assumptions underlie every scheme