Public Key

A public key is the shareable half of a cryptographic key pair, derived mathematically from its corresponding private key using elliptic curve multiplication. While the private key must remain secret, the public key (or the wallet address derived from it) can be shared openly — it is used to receive funds and to allow the network to verify that transactions were genuinely authorized by the holder of the corresponding private key.

The relationship between public and private keys is based on elliptic curve cryptography (ECC). For Bitcoin and Ethereum, this uses the secp256k1 curve. The key property is asymmetry: multiplying a private key by the generator point on the curve produces the public key, but reversing this operation — finding the private key from the public key — is computationally infeasible with current technology.

In practice, your wallet address is not exactly your public key — it is a hashed and encoded version of it. For example, a Bitcoin address is created by applying SHA-256 and RIPEMD-160 hashing to the public key, then adding a checksum and encoding in Base58. Ethereum uses the last 20 bytes of the Keccak-256 hash of the public key, prefixed with "0x." These address formats are shorter and include error-checking, making them more practical for everyday use.