5.6 Safe Computing

Big Idea 5.6

• 3 min read

Big Idea5

Safe Computing: Understanding PII, Cookies, and Encryption

Big Idea 5: Safe Computing

Safe computing revolves around Personally Identifiable Information (PII) and how it is exploited or kept secure.

What is PII (Personally Identifiable Information)?

PII includes any information that identifies a user on the internet, such as:

  • Social Security Number
  • Email
  • Full Name
  • Driver’s License

Cookies

Cookies store user information and browsing habits. They can be classified as:

  • Session Cookies: Temporary, deleted when the browser is closed.
  • Persistent Cookies: Stored for a specified duration, even after closing the browser.
  • First-Party Cookies: Set by the website for user experience and analytics.
  • Third-Party Cookies: Set by external domains (e.g., advertisers) to track user behavior.

Cookies can breach security as they track personal info and preferences.

Password Security

Strong passwords protect accounts from unauthorized access. A good password should:

  • Have a minimum of 10 characters
  • Use both uppercase and lowercase letters
  • Include at least one number
  • Contain at least one special character

Encryption

Encryption protects data by converting it into a coded format.
Types of encryption include:

  • Symmetric Encryption (Private Key Encryption)
    • Uses one key for both encryption and decryption
    • Example: AES (Advanced Encryption Standard)
  • Asymmetric Encryption (Public Key Encryption)
    • Uses a public key for encryption and a private key for decryption
    • Example: RSA
  • Hashing (One-way Encryption)
    • Converts data into a fixed-length string that cannot be reversed
    • Example: SHA-256

Where Encryption is Used:

  • Web Security: HTTPS (SSL/TLS encryption) protects websites from eavesdropping
  • Messaging Apps: End-to-end encryption ensures messages stay private

Phishing Attacks

Phishing tricks users into revealing personal information through fake emails, messages, or websites.

Types of Phishing:

  • Email Phishing: Fake emails pretending to be from trusted companies
  • Website Spoofing: Fake websites that steal login credentials
  • Smishing: Fake SMS messages from banks, delivery services, or government agencies

How to Stay Safe:

  • Don’t click on links or download attachments from unexpected emails
  • Check sender emails carefully for fake domains
  • Type website URLs manually instead of clicking links
  • Look for HTTPS and a padlock icon on websites
  • Enable spam filters to block malicious messages

Verification

Verification ensures users, systems, and software are legitimate.

  • Multi-Factor Authentication (MFA):
    Added security requiring multiple independent authentication factors.

  • Digital Signatures:
    Cryptographic technique verifying the authenticity of digital documents.

  • CAPTCHA:
    Ensures the user is human by asking them to complete simple tests (e.g. image selection).

🧠 Popcorn Hacks

🍪 Hack 1: Exploring Cookies

  1. Open Developer Tools (fn + F12 → Application → Cookies)
  2. Find a cookie from one site and analyze:
    • Name
    • Value
    • Expiration Date
    • Source (First-Party or Third-Party?)

Name: SSID Value: AqqkzWIO_x-WHBy3J Source: .youtube.com Expires: 2026-05-07T04:58:38.537Z —

🔐 Hack 2: Understanding CAPTCHA

Captcha

🧩 Homework Hack: Play with Encryption

Random shift values:

import random

def caesar_cipher(text, shift, mode):
    if shift == "random":
        shift = random.randint(1, 25)
        print(f"[INFO] Random shift used: {shift}")
    result = ""
    for char in text:
        if char.isalpha():
            shift_amount = shift if mode == "encrypt" else -shift
            new_char = chr(((ord(char.lower()) - 97 + shift_amount) % 26) + 97)
            result += new_char.upper() if char.isupper() else new_char
        else:
            result += char
    return result

mode = input("Do you want to encrypt or decrypt? ").strip().lower()
message = input("Enter your message: ")
shift = input("Enter shift value (number or 'random'): ")
shift = int(shift) if shift.isdigit() else "random"

output = caesar_cipher(message, shift, mode)
print(f"Result: {output}")


[INFO] Random shift used: 6
Result: nkrru znoy oy g zkyz