Public-Key Cryptography

Public-key cryptography uses a pair of mathematically related keys: a private key (kept secret) and a public key (shared freely). In blockchain, your private key signs transactions, proving you authorized them. Your public key (or an address derived from it) is your identity on the network. The beauty of this system is that anyone can verify a signature using your public key, but only you can create signatures with your private key. Blockchains primarily use Elliptic Curve Cryptography (ECC), specifically the secp256k1 curve.