Pay-to-Public-Key (P2PK)

Pay-to-Public-Key, or P2PK, is Bitcoin's original output type, which locks coins directly to a public key rather than to a hash of one. Satoshi-era mining rewards used P2PK, and researchers estimate that on the order of 1.7 million BTC remain in such outputs, largely untouched since 2009 and 2010.

Why it matters

P2PK was quickly superseded by pay-to-public-key-hash, which shortened addresses and, importantly, kept the public key hidden until the coins were spent. Because P2PK exposes the raw public key on chain permanently, those outputs are the first coins at risk if large-scale quantum computers ever break elliptic curve cryptography, a scenario experts still consider distant but study seriously. The dormant Satoshi-era P2PK coins have become a fixture of quantum debates, since their owner cannot be asked to migrate them.

In the gold vs bitcoin debate

P2PK's legacy raises a distinctive bitcoin question with no gold analogue: what a network does with coins whose cryptographic protection ages. Proposals range from leaving them untouched, honoring property absolutely, to eventually freezing quantum-vulnerable outputs to prevent a destabilizing theft. Gold never confronts this, its advocates note, because atoms do not depend on assumptions that can expire. Bitcoin's response is that migration paths exist for active holders and that the system has upgraded its cryptographic norms before.