6. Cryptography

Encryption Uses

6a.
Research and explain to your counselor three situations where encryption is used in cybersecurity. For each situation, describe what kind of encryption is used and why it is important.

Encryption is the art of turning readable information into scrambled nonsense that only authorized people can unscramble. It has been used for thousands of years — Julius Caesar shifted letters in his military messages, and the Enigma machine encrypted Nazi communications in World War II. Today, encryption is everywhere. Every time you see a padlock icon in your browser, encryption is at work.

How Encryption Works (The Short Version)

Encryption uses a key (a piece of mathematical information) to scramble data. Only someone with the correct key can unscramble it. There are two main approaches:

  • Symmetric encryption — the same key encrypts and decrypts the data. Fast, but both parties must share the key somehow. Think of it as a lockbox where both people have identical keys.
  • Asymmetric encryption (public-key cryptography) — uses two mathematically linked keys: a public key (which anyone can see) and a private key (which only you have). Data encrypted with the public key can only be decrypted with the private key. This solves the key-sharing problem.

Three Situations Where Encryption Is Used

Here are several real-world situations to consider for your counselor discussion. You need three — research these or find your own.

1. HTTPS Web Browsing

Every time you visit a website with “https://” in the URL and a padlock icon, your connection is encrypted using TLS (Transport Layer Security). This prevents anyone between you and the website — your ISP, a hacker on the same Wi-Fi, or a government — from reading the data you exchange.

  • What is encrypted: Everything you send and receive — login credentials, form submissions, page content, cookies
  • Type of encryption: Uses asymmetric encryption to establish the connection, then switches to faster symmetric encryption (usually AES) for the actual data transfer
  • Why it matters: Without HTTPS, logging into your email on public Wi-Fi would be like shouting your password across a crowded room

You will explore this hands-on in Req 6b.

2. Messaging Apps (End-to-End Encryption)

Apps like Signal, WhatsApp, and iMessage use end-to-end encryption (E2EE), which means messages are encrypted on your device and only decrypted on the recipient’s device. Not even the app company can read your messages.

  • What is encrypted: Text messages, photos, videos, voice calls — everything sent through the app
  • Type of encryption: Asymmetric encryption (each user has a public/private key pair). The Signal Protocol is the standard used by most major messaging apps.
  • Why it matters: Without E2EE, the company running the messaging service could read your private conversations, and a breach of their servers would expose every message

3. Full-Disk Encryption

Full-disk encryption scrambles everything on your hard drive or phone storage. If someone steals your device, they cannot read your files without your password — even if they remove the hard drive and connect it to another computer.

  • What is encrypted: The entire storage device — all files, apps, and system data
  • Type of encryption: Symmetric encryption (usually AES-256). Your password or biometric unlocks the decryption key stored in a secure hardware chip.
  • Why it matters: Without full-disk encryption, a stolen laptop is an open book. With it, a stolen laptop is a brick.
  • Where you see it: BitLocker (Windows), FileVault (macOS), and default encryption on modern iPhones and Android devices

Other Situations to Consider

  • VPN connections — encrypt all internet traffic between your device and the VPN server (as discussed in Req 5a)
  • Password storage — password managers encrypt your password vault with AES-256
  • Digital signatures — prove that a document or software update genuinely came from its claimed source and has not been tampered with
  • Email encryption — PGP/GPG encrypts email messages so only the intended recipient can read them (covered in Req 6c)
  • Cloud storage — services like iCloud and Google Drive encrypt your files at rest on their servers

Preparing for Your Counselor

For each of your three situations, be ready to explain:

  1. What data is being protected and from whom
  2. What type of encryption is used (symmetric, asymmetric, or both)
  3. Why encryption is important in that specific situation — what would happen without it?
The Need for Encryption — Khan Academy Interactive lessons on why encryption exists, how it works, and where it is used in everyday life. Link: The Need for Encryption — Khan Academy — https://www.khanacademy.org/computing/computers-and-internet/xcae6f4a7ff015e7d:online-data-security/xcae6f4a7ff015e7d:data-encryption-technique
Diagram comparing symmetric encryption (one shared key) and asymmetric encryption (public and private key pair)