Toolbox
Paste scrambled text and pick a tool. Real players use a program called CyberChef for the same jobs.
The result shows here.
What is capture the flag?
Someone hides a secret, the flag, and you use real skills to find it. Here every flag looks like FLAG{some_words}. A flag proves you solved the puzzle, like a code word hidden behind the part that failed in a training car.
The name comes from the outdoor game. Security conferences borrowed it in the 1990s, and DEF CON's contest is the famous one.
How to play
- Pick any puzzle. They get harder as you go down the page, but you can jump around.
- Each solved puzzle is worth 100 points. Each hint you open costs 20, down to a floor of 40.
- After a solve, read the explanation. That's the part you keep.
The rule that never changes: only test machines you own or have written permission to test. Everything here is a simulation made for practice. Trying the same ideas on a real site or someone else's device can be a crime, even out of curiosity.
Words
- Encoding changes how data is written. Anyone can reverse it. No key needed.
- Encryption locks data so that only someone with the key can read it.
- Log: a diary a computer keeps of what happened.
- Packet: one small envelope of data on a network.
- Port: a numbered door on a computer, one for each service.
- Cookie: a small note a website asks your browser to keep and hand back.