BIP-322 nit fixes #2162

pull scgbckbone wants to merge 1 commits into bitcoin:master from scgbckbone:bip322_break_changes changing 1 files +4 −4

scgbckbone commented at 12:29 PM on May 19, 2026: contributor
Hi,

Writing from the Coldcard team — we shipped BIP-322 Proof-of-Reserves on 2026-03-06, before #2141 was merged. Reading the BIP-322 related PRs from last weeks it seems you have no idea we have live BIP-322 support in prod.

Refs:
As I understand updated BIP, none of the prefix business is part of Signer (HWW) flow. So we will be adding PSBT_GLOBAL_GENERIC_SIGNED_MESSAGE + relaxing the requirement for 0th input to have non-witness utxo. Nothing else.

Thank you for moving the BIP forward!

One more observation: the pof prefix on the wire format looks structurally redundant. The spec already requires PSBT_GLOBAL_GENERIC_SIGNED_MESSAGE to be present, plus the prevout-of-to_spend and single-OP_RETURN-output rules — and PSBTs are self-marked at position 0 of the base64 (always start with cHNidP8). Dropping the prefix would let verifier-side libraries feed the base64 straight into their existing PSBT parsers (without any change).

For future BIP-322 work we'd appreciate being tagged/contacted.

Thanks.

PR patch-list contains few small issues I found while reading...
nit fixes 6a36f95565
scgbckbone commented at 12:32 PM on May 19, 2026: contributor

https://gist.github.com/orangesurf/0c1d0a31d3ebe7e48335a34d56788d4c

this is now also obsolete as PSBT_GLOBAL_GENERIC_SIGNED_MESSAGE is required by BIP to be in PSBT globals
jonatack added the label Proposed BIP modification on May 19, 2026

in bip-0322.mediawiki:170 in 6a36f95565

 166 | @@ -167,7 +167,7 @@ A ''full'' signature consists of the variant-prefixed (<code>ful</code>) base64-
 167 |  
 168 |  === Full (Proof of Funds) ===
 169 |  
 170 | -The [[#full-proof-of-funds|Proof of Funds]] variant extends the basic scheme: in addition to signing
 171 | +The Proof of Funds variant extends the basic scheme: in addition to signing

jonatack commented at 9:35 PM on May 19, 2026:

Right, the link here no longer makes sense since this sentence was moved to the start of the section.

jonatack commented at 9:44 PM on May 19, 2026: member

ACK, good fixups.

Thank you, @scgbckbone, I've noted to cc you on further BIP 322 changes.

One more observation: the pof prefix on the wire format looks structurally redundant. The spec already requires PSBT_GLOBAL_GENERIC_SIGNED_MESSAGE to be present, plus the prevout-of-to_spend and single-OP_RETURN-output rules — and PSBTs are self-marked at position 0 of the base64 (always start with cHNidP8). Dropping the prefix would let verifier-side libraries feed the base64 straight into their existing PSBT parsers (without any change). @guggero thoughts on this?
jonatack merged this on May 19, 2026
jonatack closed this on May 19, 2026
jonatack removed the label Proposed BIP modification on May 19, 2026
jonatack added the label Fixups on May 19, 2026

in bip-0322.mediawiki:499 in 6a36f95565

 492 | @@ -493,7 +493,7 @@ and many others for their feedback on the specification.
 493 |  ** Mark Complete
 494 |  ** Breaking change: Add human-readable prefix to encoded signature
 495 |  ** Breaking change: format of "Proof of Funds" signatures to be base64-encoded finalized PSBT
 496 | -** Add new PSBT input field for PSBT-based signing
 497 | +** Add new PSBT global field for PSBT-based signing
 498 |  * '''0.0.1''' (2018-09-10):
 499 |  ** Proposed as draft
 500 |

jonatack commented at 10:00 PM on May 19, 2026:

Good catch (https://github.com/bitcoin/bips/pull/2141#discussion_r3269869685)

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scgbckbone

jonatack

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#2141 BIP-0322: clarify motivation/purpose, add prefix, clarify Proof of Funds format, describe PSBT based signing