Security basics

Core ideas that keep systems and data safe.

📖 Key ideas

The CIA triad: confidentiality, integrity, availability.
Hashing (SHA-256, bcrypt) turns data into a fixed fingerprint; passwords should be hashed with salt.
Symmetric encryption uses one key; asymmetric uses a public and private key pair.
Common attacks: phishing, SQL injection, XSS, malware.
Least privilege and updates reduce risk.

💡 Real-life example: Like a bank: only you see your balance (confidentiality), nobody can change it secretly (integrity), and the bank opens when you need it (availability).

CIA triadConfidentiality, integrity, availability

HashOne-way fingerprint of data

Public keyKey you can share to receive encrypted data

PhishingTricking people into giving secrets