Context

This room provides an understanding of cryptography in our everyday digital encounters.

how do we actually protect secrets and detect tampering in the real world? That's where cryptography comes in.

Starting hypothesis

• Explain what cryptography is and why it matters for protecting confidentiality and integrity.
• Describe the difference between plaintext and ciphertext with actual examples.
• Explain what keys and algorithms are, and why keeping keys secret is critical.
• Explain the difference between symmetric and asymmetric encryption using everyday objects, such as lockboxes and mailboxes.
• Describe how symmetric and asymmetric encryption work together to protect your web browsing.

Method / Used Tools

Hiding Information - Symmetric Encryption

Understanding the Basics

In cryptography, the first step is understanding the building blocks. Messages we want to protect are called plaintext—readable text like HELLO or Patient name: Alice Smith. When we scramble these messages to hide their content, they become ciphertext, something that looks like KHOOR or Sdwlhqw qdph: Dolfh Vplwk.

At the heart of this process is the key—a secret value that controls how scrambling and unscrambling work. Think of it as a password the algorithm uses. The algorithm itself is the recipe: a set of steps that defines how the key is applied to the message. Algorithms are usually public; security comes from keeping the key secret.

The basic flow is simple:

• Encryption: plaintext + encryption algorithm + key → ciphertext
• Decryption: ciphertext + decryption algorithm + key → plaintext

While modern cryptography is far more sophisticated, this pattern underlies nearly all secure communication.

The Lockbox Analogy