Cryptography Guide 🔐🧠

1. What is Cryptography?

Cryptography is the technique of securing information using encryption and decryption.

2. Types

Symmetric → One key (fast)
Asymmetric → Public + Private key
Hashing → One-way function

3. Example

Text → Encryption → Cipher → Decryption → Text

4. Algorithms

AES → Symmetric
RSA → Asymmetric
SHA → Hashing

5. Real Uses

HTTPS → Secure websites
Passwords → Hashing
Blockchain → Crypto security

6. Security Goals

Confidentiality → Data privacy
Integrity → No changes
Authentication → Verify identity

7. Tools & Libraries

OpenSSL
bcrypt
crypto (Node.js)

8. Real Use Cases

• Secure login systems 🔐
• Online payments 💳
• Data protection 📦
• API security 🔗