All labs · 🔐 Code breakers
Secret codes and how to crack them
From Julius Caesar to your passwords today: encode secret messages, crack them like a spy, and learn why long passwords keep you safe.
Julius Caesar moved every letter along the alphabet by the same number. Turn the wheel: the outside letter becomes the inside one.
🐍 In Python
Caesar is easy to crack: every letter moves the same. Vigenère uses a keyword – each letter of the key gives a different shift, so E isn't always the same letter.
The secret weapon of code breakers: in English, E is the most common letter, then T and A. Compare the letters of the message (teal) with normal English (grey).
normal English this message
Try all 26 shifts
📡 Morse code
Dots and dashes – sent by light, sound or radio since 1840.
🔢 Letters are numbers
Computers store every letter as a number (ASCII / Unicode)…
💻 …and numbers as binary
8 ones and zeros (a byte) for each letter.
Decode Morse
Spaces between letters, / between words.
Decode binary
#️⃣ Hashing: a one-way fingerprint
A hash turns any text into a fixed fingerprint. You can't turn it back – so websites store the hash of your password, not the password. Change one letter and watch:
🛡️ How strong is a password?
Try some (they never leave this page). Longer beats cleverer!
- Use 4 random words:
purple-tiger-rice-moon - Never reuse a password on two sites
- Never use names, birthdays or “password”