Secret Code
Teaches: Keys & Wallets | 5 min | You need: Nothing!
What you will learn
You can prove something is yours using a secret key, without showing the key itself.
Steps
- 1
Pick a secret number. This is your PRIVATE KEY. Example: 7.
- 2
Create a rule from it. This is your PUBLIC KEY. Example: "multiply by 7".
- 3
To "sign" the number 3: calculate 3 x 7 = 21. Tell someone "21".
- 4
They know your rule (multiply by 7). They check: 21 / 7 = 3. It matches! VERIFIED.
- 5
Spot the problem: the rule "multiply by 7" tells everyone your secret number! A toy rule like this cannot keep it hidden.
- 6
Real Bitcoin keys use one-way maths with huge numbers: the public key is made from the private key, but nobody can work backwards to find the private key.
What you learned
Public keys let anyone verify your identity. Private keys prove you are the owner. Never share your private key.
Play with others?
Each person picks a secret number and shares only the rule. Others verify signed messages. Then ask: could they work out the secret from the rule? (Yes! That is why real Bitcoin needs one-way maths.)