One-sentence answer
A lets its holder create a valid authorizing the next spend of funds without revealing the key itself.AT A GLANCE · EXPAND A STEP
01Private key stays local
It authorizes without being sent to all validators.
02Signature binds a message
Changing the message makes the original signature fail.
03Public verification
A public key and signature help check authorization without revealing the private key.
This diagram explains relationships, not the complete protocol implementation.
A private key is not a login password
A password is usually sent to a server for checking. A Bitcoin stays local and creates a . verify the signature using public information without learning the .
The network can verify authorization without a central database of user passwords.
Wallets, seed phrases, and addresses
Wallet software generates and manages keys. A seed phrase can usually restore a group of keys and must be protected as highly sensitive information. An address can be shared to receive funds, though reuse can expose transaction relationships.
Entering a seed phrase into an unknown website effectively hands over control of the funds.
Key control brings responsibility
Self-custody reduces dependence on a custodian, but losing keys usually leaves no “forgot password” button. Backups, phishing resistance, and device security become the user’s responsibility.
Try it: a signature binds a message
Teaching limits: browser ECDSA P-256, not Bitcoin’s secp256k1 or its full signing-message format. Only demonstrates message binding. No wallets or real keys.
CHECK YOUR UNDERSTANDING
Does checking a signature require handing over the private key?
A correct answer saves local progress. No account needed.View my learning pathThree things to remember
- ✓Private keys create signatures and should never be submitted or shared.
- ✓A seed phrase can restore many keys and is extremely sensitive.
- ✓Self-custody brings both independence and irreversible responsibility.
A common follow-up
Can someone steal bitcoin by knowing my address?
An address alone is generally not enough to spend funds; a valid signature is required. Public addresses can still reveal transaction relationships and affect privacy.
Primary sources
Primary sources
These links lead to protocol material, developer documentation, or open-source code—not trading services.