NotATether: create Pay-to-anchor stub (BIP 433 P2A template)

2026-09-06T07:24:15Z

create Pay-to-anchor stub (BIP 433 P2A template)

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'''Pay-to-anchor''' (P2A) is a keyless native [[Segregated Witness]] version 1 output type described by [https://github.com/bitcoin/bips/blob/master/bip-0433.mediawiki BIP 433]. The scriptPubKey is <code>OP_1 <0x4e73></code>, serialized as the bytes <code>0x51 0x02 0x4e 0x73</code>. On mainnet the corresponding [[Bech32m]] address is <code>bc1pfeessrawgf</code>. Spending requires an empty witness. Anyone able to broadcast a child that spends the output can attach fees. P2A names the output template. It is not the same as a keyed Lightning <code>option_anchors</code> output, and it is not the same as an [[Ephemeral_anchor|ephemeral anchor]], which is a usage pattern that combines a P2A output with [[TRUC]] policy and ephemeral dust.

Because the program is a native witness output, BIP 141 requires a blank scriptSig, so the spending transaction's txid is stable against scriptSig malleation. Bitcoin Core treats a non-empty witness as nonstandard for this template, which keeps the wtxid stable against witness padding under standard relay. Consensus still accepts any witness. BIP 433 recommends combining P2A with TRUC to bound pinning by an oversized low-feerate child. Bitcoin Core 28.0 made P2A spends standard. Core 29.0 added ephemeral-dust policy for a zero-value P2A spent in the same package.

== See also ==

* [[Ephemeral_anchor|Ephemeral anchor]]
* [[TRUC]]
* [[Lightning Network]]
* [[Segregated Witness]]
* [[Bech32m]]

== External links ==

* [https://github.com/bitcoin/bips/blob/master/bip-0433.mediawiki BIP 433: Pay to Anchor (P2A)]
* [https://github.com/bitcoin/bips/blob/master/bip-0431.mediawiki BIP 431: Topology Restrictions for Pinning]
* [https://github.com/bitcoin/bitcoin/pull/30352 Bitcoin Core PR 30352]
* [https://bitcoinops.org/en/topics/ephemeral-anchors/ Bitcoin Optech: Ephemeral anchors]

[[Category:Technical]]

Pay-to-anchor - Revision history

NotATether: create Pay-to-anchor stub (BIP 433 P2A template)