Proving ownership without revealing your secret key
Your Bitcoin is protected by a secret "private key" that only you know. To spend Bitcoin, you create a "digital signature" that proves you own it WITHOUT revealing your private key. Anyone can verify the signature is real using your "public key."
Bitcoin uses elliptic curve cryptography (secp256k1) for digital signatures. Private keys sign transactions, public keys verify signatures. The mathematical relationship is one-way: easy to derive public from private, impossible to reverse.
Bitcoin implements ECDSA (Elliptic Curve Digital Signature Algorithm) over secp256k1 curve. Private key k generates public key P = k·G where G is generator point. Signature (r,s) proves knowledge of k without revealing it. Verification: s⁻¹(H(m)·G + r·P) = R validates ownership.
Private Key (Keep Secret!):
🔓 Public Key (Share Freely):
Create Digital Signature:
Digital Signature:
Test signature verification - try changing the message or tampering with the signature!