P2PKH (Pay-to-Public-Key-Hash)

Pay-to-public-key-hash is the bitcoin script format that locks coins to a 20-byte hash of a public key rather than to the key itself. Introduced early in bitcoin's history and recognizable by addresses beginning with the numeral 1, it kept the public key secret until spend time and remained the dominant output type for over a decade.

How it works

The recipient's public key is hashed with SHA-256 and then RIPEMD-160, and only that digest appears on chain. To spend, the owner reveals the full public key and a signature, and the network checks that the key hashes to the committed digest before verifying the signature. The design shortens addresses and adds a second cryptographic layer: an attacker facing an unspent P2PKH output must break the hash functions, not just the elliptic curve.

That layering has consequences for quantum risk. Coins in P2PKH addresses that have never been spent from hide their keys behind hashes that Shor's algorithm cannot attack, so good address hygiene meaningfully shrinks the vulnerable set.

In the gold vs bitcoin debate

P2PKH is a reminder that bitcoin's security is a stack of choices, not a single lock. Gold's defense is one property, physical inertness, applied uniformly. Bitcoin's defense varies by script type and user behavior, which critics call fragility and defenders call upgradeability.