What Is Encryption?
Encryption hides a message’s contents. See how encryption and decryption work with a simple locked-box example.
Free video lesson · 1:15
What Is Encryption?
Quantum Computing & Encryption for Beginners
Music: “Thinking Music” by Kevin MacLeod. Creative Commons Attribution 4.0.
Encryption hides the contents of a message; decryption makes it readable again.
Read the video transcript
Encryption turns a readable message into data that other people cannot understand. Think of it as putting your message inside a locked box. The message is still there. Its contents are hidden.
Imagine you send a friend the words, meet at the park. Your app encrypts them before sending them. Someone copying the message along the way gets the encrypted version, not those readable words.
Your friend uses a digital key to unlock the message. A key is a value the software uses to turn that encrypted data back into words. This reverse step is called decryption.
The box is only a picture. Real encryption uses mathematics. Good encryption is designed to make reading the message without the right key far too difficult to be practical.
So encryption protects what a message says. Once someone unlocks it, they can read it, and they could share it. Encryption cannot control what a person does with words they can already see.
What does the digital key do? Watch What Is an Encryption Key? For the version with two different keys, watch What Is Public-Key Cryptography?
The short answer
Encryption turns a readable message into data that other people cannot understand. Think of it as putting your message inside a locked box. The message is still there. Its contents are hidden.
A simple example
Imagine you send a friend the words, meet at the park. Your app encrypts them before sending them. Someone copying the message along the way gets the encrypted version, not those readable words.
Your friend uses a digital key to unlock the message. A key is a value the software uses to turn that encrypted data back into words. This reverse step is called decryption.
The box is only a picture. Real encryption uses mathematics. Good encryption is designed to make reading the message without the right key far too difficult to be practical.
So encryption protects what a message says. Once someone unlocks it, they can read it, and they could share it. Encryption cannot control what a person does with words they can already see.
What stays visible?
Encryption protects the contents of a message. It does not automatically hide who sent it, who received it, or when it was sent. Those details depend on the app and its design.
Check your understanding
If a friend takes a screenshot after opening your message, does encryption stop them sharing it?
Answer
No. The friend can already read the message. Encryption protects it while locked, not every later use.
Keep learning
Follow the free video course one question at a time. For help applying these ideas at work, explore team training or a cryptography audit.