bip-0360: added python reference example; test vector fixes by notmike-5 · Pull Request #2202 · bitcoin/bips

notmike-5 · 2026-06-26T19:23:47Z

This PR adds a python reference example for construction of BIP-360 outputs and control blocks.

It updates the test vectors to remove "internalPubkey" key from vectors 7 and 8, and adds a new test for duplicate script leaves.

This PR also brings in fixes to #2102 and #2103 from @jbride

…d to match tree structure of test vectors (bitcoin#45)

…ng construction of P2MR output (bitcoin#46)

leaf version

This commit adds a python reference example for construction of BIP-360 outputs and control blocks. This commit also updates the test vectors.

murchandamus

Looks reasonable at first glance.

cc: @cryptoquick, @EthanHeilman, @Isabelfoxenduke for owner review/sign-off.

This refactors `compute_control_block` to improve performance, and make the function simpler to read (to me at least). The previous version walked the entire script tree searching for the first matching instance of the leaf node. The new version expects the caller to pass in an explicit `path` parameter, which tells us exactly where the leaf node lives, with left/right steps encoded as bits in an integer. We walk down the tree straight to that leaf node, and build the control block as we go. This might not be the best DX for a real-world API or library, but this is just reference code, so we can accept poor usage ergonomics if it makes the code clearer and more explicit.

conduition · 2026-06-26T23:24:26Z

+# Bech32 encoding code is taken from sipa (BIP-0350), and has been tested against the test vectors therein:
+# https://github.com/sipa/bech32/blob/master/ref/python/tests.py


Most of this code already exists in the BIPs repository, under the reference code of BIP352 (silent payments).

https://github.com/bitcoin/bips/blob/master/bip-0352/bech32m.py

@murchandamus What are your thoughts on the bech32m code duplication here? is it better to duplicate for the sake of compartmentalization, or should we update the existing code and reference it here?

I’d prefer it to be compartmentalized. This is not a software project, so I would prefer if we don’t slip into starting to maintain the reference implementations of all the BIPs here.

Would it be more convenient if we move the BIP360 reference implementations into an external repository?

That sounds great to me.

OK, i'll see about closing this PR out and moving the code to a new repository. Please give us some time to get the new repo set up and the code moved over

Should the test vectors stay in the bips repo? Test-vectors and reference implementations are inter-connected: reference implementations are tested against test-vectors and test-vectors can be updated (canonized) using a reference implementation.

Either is acceptable. Especially for small reference implementations, both are often supplied with the BIP in the auxiliary files. Especially for larger endeavors, the BIPs often just link to the reference implementation, and test vectors may be provided with the BIP or also linked to.

bip360: simplify computing control blocks using explicit traversal paths

Implements @conduitions improvement on tapbranch_hash() Co-authored-by: conduition <conduition@proton.me>

Standardizes all P2MR-specific functions to use bytes uniformly for input/output. Hex conversions are now confined to two boundaries: reading `script` field out of ScriptTree input, and comparing against hex-encoded test vector data in `run_single_test`. bech32 functions and s2w are left unchanged.

cryptoquick · 2026-07-04T00:24:50Z

Thanks for this work. I'm a little confused as to where it's going to land though. Is there a decision being made regarding reference implementations? Will they all be stripped from the BIPs repository? Will they be fragmented or live in a separate repository? Where is this policy and decision making documented? Who is being consulted in this decision and who are the stakeholders?

murchandamus · 2026-07-06T18:41:05Z

Providing the reference implementation with the BIP or linking to a branch that contains it are acceptable.

@cryptoquick: If you expect that BIP360 is going to continue to evolve, it would be preferable for the reference implementation to be maintained outside of this repository to allow you to move independently of pull requests to the BIPs repository. If this PR wraps up planned work on BIP360’s reference implementation, or you are just going to PR a small count of further updates from a development branch it might as well stay here.

If you do plan on completely revamping the ideas behind BIP360 another time, it might make sense to publish the result as a separate BIP, since P2MR has been getting quite a bit of discussion already.

conduition · 2026-07-06T21:41:02Z

I can't speak to what @cryptoquick is working on, but within my sphere of knowledge I expect at least one more major change will be filed towards BIP360 in the near future, which will be to apply @starius's EC key recovery idea to get shorter EC spend witnesses (background).

I believe @starius is currently working on a separate BIP specifically for the signature scheme and plans to file a pull request to change BIP360 later once that spec is more complete. This change would not affect the core functionality or features of BIP360 - it would merely change the order of validation operations slightly. I don't believe the BIP360 python reference code would need to change (IDK about the Rust/JS code). The bulk of the complexity will live in a separate BIP.

murchandamus · 2026-07-08T22:46:51Z

The way I perceive it, we’re just providing a public service to facilitate people sharing their protocol development ideas in a central publication medium. That said, we are focused on the text documents here, and while we require reference implementations to exist before a proposal is advanced to Complete, reference implementations are not reviewed at the same level as the proposals themselves by the BIP Editors.
Reference implementations would be expected to get more review/attention from implementers after a proposal has been advanced to Complete.
One can be submitted with the BIP, but it is not intended for reference implementations to be developed against the BIPs repository. Especially if the reference implementation of a proposal is still an on-going project, it would be simpler for all parties if the reference implementation were situated in a separate repository.

jbride and others added 4 commits June 25, 2026 19:59

bip360 test vectors: elements in control block array should be ordere…

35b9ffe

…d to match tree structure of test vectors (bitcoin#45)

bip360 test vectors: non-standard leaf version should be allowed duri…

907db20

…ng construction of P2MR output (bitcoin#46)

bip360 test vectors: control block now reflects use of non-standard

8d28eb4

leaf version

bip-0360: added python reference example; test vector fixes

29e1a15

This commit adds a python reference example for construction of BIP-360 outputs and control blocks. This commit also updates the test vectors.

murchandamus reviewed Jun 26, 2026

View reviewed changes

murchandamus added Proposed BIP modification PR by non-owner to update BIP content Pending acceptance This BIP modification requires sign-off by the champion of the BIP being modified labels Jun 26, 2026

murchandamus mentioned this pull request Jun 26, 2026

bip360: use correct leafVersion in control block byte for non-default version leaves #2103

Closed

conduition added 3 commits June 27, 2026 01:11

add new test case for duplicate script leaves

86e7f9d

return type is not optional anymore

1325ccc

conduition reviewed Jun 27, 2026

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conduition mentioned this pull request Jun 27, 2026

BIP360: swap scriptPathControlBlocks[1] and [2] for three-leaf P2MR test vectors #2102

Closed

notmike-5 and others added 7 commits June 26, 2026 19:32

Merge pull request #1 from conduition/360/p2mr-compute-control-block

9fafbb7

bip360: simplify computing control blocks using explicit traversal paths

bip360: Optional type removed / no longer needed

2706a61

bip360: simplify tapbranch_hash function

50a6b91

Implements @conduitions improvement on tapbranch_hash() Co-authored-by: conduition <conduition@proton.me>

bip360: make consistent use of h2b

9bf46b5

bip360: much cleaner, more readable s2w function

ac2aa2f

bip360: move collect_leaf_hashes() to the test code section

8ea1eaa

bip360: minor syntax fix on tapbranch_hash()

64d068e

starius reviewed Jun 27, 2026

View reviewed changes

Comment thread bip-0360/ref-impl/rust/tests/p2mr_construction.rs Outdated

conduition reviewed Jun 28, 2026

View reviewed changes

Comment thread bip-0360/ref-impl/python/p2mr.py Outdated

notmike-5 added 2 commits June 27, 2026 22:40

bip360: mask tapleaf_version in tapleaf_hash

75167ec

bip360: cleanup rust tests a bit and remove unused imports

3e3e434

		# Bech32 encoding code is taken from sipa (BIP-0350), and has been tested against the test vectors therein:
		# https://github.com/sipa/bech32/blob/master/ref/python/tests.py

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