Security Fundamentals

Computer security protects systems and data from unauthorized access, attacks, and damage.

Key Concepts

• CIA Triad — Confidentiality, Integrity, Availability
• Authentication — verifying identity
• Authorization — granting access
• Encryption — protecting data

Syntax

COMPUTER-SCIENCE

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# Hashing (one-way)
import hashlib
hash_obj = hashlib.sha256("password".encode())
print(hash_obj.hexdigest())

# Encryption
from cryptography.fernet import Fernet
key = Fernet.generate_key()
cipher = Fernet(key)
encrypted = cipher.encrypt(b"secret")

Hashing and Encryption

PYTHON

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import hashlib

# Password hashing
def hash_password(password):
    return hashlib.sha256(password.encode()).hexdigest()

# Verify password
def verify(password, hashed):
    return hash_password(password) == hashed

password = "mySecret123"
hashed = hash_password(password)
print(f"Password: {password}")
print(f"Hash: {hashed}")
print(f"Verify correct: {verify(password, hashed)}")
print(f"Verify wrong: {verify('wrong', hashed)}")

Try It Yourself

Practice

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Exercise

What is the CIA Triad?

Answer

Confidentiality (secrecy), Integrity (accuracy), Availability (access).

Quick Quiz

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What is encryption?

Deleting data

Converting data to unreadable format

Backing up data

Compressing data

Encryption converts readable data into unreadable format to protect it.

Retry Quiz

Interview Questions

What is the difference between hashing and encryption?

Hashing is one-way (can't reverse). Encryption is two-way (can decrypt with key). Hashing for passwords, encryption for data protection.

Tutorial Complete

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