What is a Bitcoin Pay-to-Public-Key-Hash (P2PKH)?

Bitcoin Pay-to-Public-Key-Hash (P2PKH) is a type of transaction output script used in the Bitcoin protocol to enable the spending of bitcoins. It is one of the simplest and most commonly used transaction types in Bitcoin transactions. P2PKH transactions were introduced as part of the original Bitcoin protocol.

Here's how P2PKH transactions work:

1. **Public Key Hash**: In a P2PKH transaction, the locking condition for spending bitcoins is based on the hash of a public key, known as the Public Key Hash (PKH). The PKH is derived from the recipient's public key using a cryptographic hash function.

2. **Bitcoin Address**: The PKH is typically encoded into a Bitcoin address using a base58 encoding scheme, resulting in a shorter and more human-readable representation of the PKH. The Bitcoin address serves as the identifier for the recipient's wallet and is used to receive bitcoins.

3. **Transaction Output**: A P2PKH transaction output contains the Public Key Hash (PKH) as the locking condition, indicating that the bitcoins can only be spent if the spending transaction provides a valid signature corresponding to the public key associated with the PKH.

4. **Signature Verification**: When spending bitcoins from a P2PKH output, the spending transaction must include a digital signature generated using the private key corresponding to the public key associated with the PKH. The signature is used to verify the authenticity and authorization of the spending transaction.

P2PKH transactions offer several advantages:

- **Simplicity**: P2PKH transactions are simple and easy to understand, making them widely supported by Bitcoin wallets and exchanges.

- **Security**: P2PKH transactions provide a high level of security, as they require possession of the private key corresponding to the public key hash in order to spend the bitcoins.

- **Privacy**: While P2PKH transactions reveal the recipient's Bitcoin address on the blockchain, they do not reveal the details of the recipient's public key, providing some level of privacy for the recipient.

However, P2PKH transactions also have some limitations:

- **Space Efficiency**: P2PKH transactions can be less space-efficient compared to more advanced transaction types, as they require including the full public key hash in the transaction output, resulting in larger transaction sizes and higher fees.

Overall, P2PKH transactions remain a fundamental building block of the Bitcoin protocol and are widely used for everyday transactions on the Bitcoin network.