Public Key
A public key is the cryptographic counterpart to a private key, derived through elliptic curve multiplication. It is used to generate Bitcoin addresses and verify digital signatures without revealing the private key.
How It Works
A public key is mathematically derived from a private key using elliptic curve cryptography on the secp256k1 curve. This one-way function means anyone can verify that a public key corresponds to a signature, but nobody can work backwards to determine the private key. This is the fundamental mechanism that makes Bitcoin work without any central authority.
Bitcoin addresses are actually hashes of public keys, not the public keys themselves. This provides an additional layer of security: until you spend from an address, only the hash of your public key is exposed on the blockchain. The full public key is only revealed when you create a transaction, which is one reason address reuse is discouraged.
In modern Bitcoin usage with Taproot (P2TR) addresses, the public key model has been refined further. Schnorr signatures used in Taproot provide more efficient verification and enable advanced features like key aggregation for multisig setups, all while keeping the same fundamental security model.
Key Points
- Derived from the private key using one-way elliptic curve multiplication on secp256k1
- Used to generate Bitcoin addresses and verify transaction signatures
- Only fully revealed on-chain when you spend from an address
- Address reuse exposes public keys unnecessarily, reducing security margin
- Taproot and Schnorr signatures improve public key efficiency and privacy