Pay to public key (P2PK)

The earliest Bitcoin outputs locked coins directly to a public key. Learn how P2PK works, where to find it, and why it was replaced by P2PKH.

The simplest lock

Locking:   <public key> OP_CHECKSIG
Unlocking: <signature>

The spender only supplies a signature. OP_CHECKSIG checks it against the public key stored right in the output.

Where you'll see it

Early coinbase transactions, including the genesis block and most coins mined in 2009–2010, pay to P2PK. Many of those coins have never moved.

Why it was replaced

• The full public key (65 bytes uncompressed) sits in every output, which is bigger than a 20-byte hash.
• There's no short address format for it.
• The public key is exposed from the start rather than at spend time.

Pay to public key hash (P2PKH) solved these and became the standard.

See it in block 170

Open block 170 on MyBitcoinExplorer and the Satoshi-to-Hal transaction inside it. Both outputs show the script type pubkey: that's P2PK. There is no address in the modern sense; the explorer shows the public key itself.

P2PK and quantum computing

A large enough future quantum computer could, in theory, derive a private key from a visible public key. P2PK outputs reveal their keys before spending, so they come up first in such discussions. Coins locked by hash-based scripts only reveal keys when spent.