Add Silent Payments Support by macgyver13 · Pull Request #587 · Coldcard/firmware

macgyver13 · 2025-11-26T14:57:08Z

Finally consider this PR ready for review and feedback to determine next steps.

TODOs:

~~verify silent payments labeled address handling~~
~~verify multi sig silent payment workflows~~
~~address edge cases / attack scenarios~~
(on hold) test on real hardware - evaluate memory and performance
(partial) proper UI/UX for Silent Payments - seeking feedback

Screenshots

Updated UX with - silent payment address - appended to - to address -

Contribute Shares Prompt

macgyver13 · 2026-03-27T01:41:42Z

Still have plenty of tasks to do on this PR but wanted to provide a checkpoint given the number of changes. I can break this into multiple PRs if preferred. I expect commits 7887701 through c516610 to remain stable.

Core Changes:

fix: (psbt v2)
fix: (usb_test)

Silent Payments Changes:

Standardized testing to use pytest and simulator instead of ngu_wrapper
Added bip375_test_vectors.json and parameterized test_silentpayments to use each vector
Introduced the workflow of contributing shares but not signing when multi-signers contribute to a SP output
Silent Payments Address is now appended to UI text instead of replacing - to address -
Labeled silent payments addresses are rendered correctly for change
Added BIP376 fields and associated operations

TODOs:

Considering how to show BIP353 HRN when provided by wallet coordinator like Sparrow
Identify sensitive material areas that need to be cleared
Add more tests to handle edge cases - open to suggestions
Consider doc/silentpayments.md

macgyver13 · 2026-04-30T20:23:02Z

Summary of changes since March update:

Added bip352_test_vectors.json and test_bip352_vectors.py
Added BIP376 spend path validation
Clear sensitive material in Silent Payments workflows
Added doc/silentpayments.md
Added bip352 generic format export
Total integration tests in test_silentpayments.py:
- test_sp_signing_story
- test_sp_p2wpkh_input
- test_sp_p2tr_input
- test_sp_mixed_inputs
- test_sp_mixed_sp_spend_and_regular_input
- test_sp_three_outputs_same_scan_key
- test_sp_two_outputs_different_scan_keys
- test_sp_mixed_output_types
- test_sp_all_owned_multi_input
- test_sp_partial_owned_coverage_complete
- test_sp_partial_owned_coverage_incomplete
- test_sp_partial_owned_coverage_incomplete_refused
- test_sp_spend_silent_payment_output
- test_sp_spend_silent_payment_output_with_taproot
- test_sp_spend_wrong_tweak_rejected
- test_sp_spend_wrong_purpose_rejected
- test_sp_spend_wrong_coin_type_rejected
- test_exit_gracefully_on_sp_validation_failure
- test_sp_non_sighash_all_rejected
- test_sp_psbt_v0_rejected
- test_sp_spend_to_labeled_change_address

Testing

Targeted tests

cd testing
pytest test_bip352_vectors.py
pytest test_bip375_vectors.py
pytest test_silentpayments.py
pytest test_export.py::test_export_coldcard

General tests

DEFAULT_PYTEST_MARKS = "not onetime and not veryslow and not manual and not bitcoind"
python run_sim_tests.py --multiproc --num-proc 6

macgyver13 · 2026-06-08T18:05:08Z

Commit 106990f fixes silent payment output ordering when multiple outputs share the same scan key (labeled addresses of one recipient).

macgyver13 · 2026-07-20T18:53:24Z

Commit e08bd9c modifies the default silent payment signing flow. The wallet coordinator should be responsible for verifying the PSBT and finalizing for broadcast when silent payments are involved.

scgbckbone · 2026-07-29T12:23:56Z

am I the one blocking this with HW tests ?

Please, open libngu changes as separate libngu PR.

macgyver13 · 2026-07-29T13:04:07Z

am I the one blocking this with HW tests ?

I consider this PR stable and ready for critical review. Confirming this PR on real hardware would be great!

Please, open libngu changes as separate libngu PR.

I'll get on that. Thank you!

external/ckcc-protocol - Add bip375 and bip376 constants external/libngu - Expose ec_pubkey_combine - Expose ec_pubkey_tweak_mul - Add bip352_encode

Add bip352 crypto primitives / helpers Add bip352 tagged hashes

Add bip374 tagged hashes Add dleq bip374 reference generate_dleq_proof, verify_dleq_proof functions

Extend psbt handling with silent payment specific functions Incorporate validation functions from bip375 test vectors - psbt_structure, input_eligibility, ecdh_coverage Add private key derivation helper functions

Only store key_data for short_values - remove key_type Only serialize PSBT_OUT_SCRIPT if self.script has a value Adjust v2 script assert to not required if sp_v0_info is present

Provides silent payments testing framework with access to MockPSBT

Use devtest/verify_sp_outputs.py for simulator testing Add testing/test_bip375_vectors.py and testing/bip375_test_vectors.json - Correct input eligibility ecdh share assumptions Add devtest/unit_silentpayments.py to perform unit testing via simulator Mirror psbt fields in testing/psbt.py

Add testing/test_bip352_vectors.py and testing/bip352_test_vectors.json - Verify SP sending and receiving test vectors

Integrate preview silent payment address as output in auth:interact Integrate silent payments in signing workflow Add sp_hrp property to chains.py Add silent payments fields to psbt.py

Add sp_spend support to _derive_input_privkey Validate bip376 spend key derivation

Create end-to-end tests for SP in testing/test_silentpayments.py - Expose foreign_mk for partial ownership coverage test Integrate SP spend into psbt functions: consider_inputs, determine_my_signing_key, sign_it - Synthesize parsed_subpaths from PSBT_IN_SPEND_BIP32_DERIVATION - Set input.sp_idxs to placeholder to synthesize input is_owned - Implement SP input signing Refactor _compute_and_store_ecdh_shares and _derive_input_privkey to leverage input.sp_idxs

Add test to validate 'Contribute Shares?' UX Simplify SP preview and signing code paths

Add silent payments label change tests - Detect presence or absence of 'Change back:' in UI story Add multi-signer incomplete coverage scenario tests

Verify SP spend path was derived from m/352h Add signature verification for taproot inputs and SP outputs

Include key-value pairs: spscan, deriv, name, xfp, key_exp in bip352 dictionary Add bip352 test block to test_export_coldcard Support 127 character limit for silent payments v0

Mixed inputs SP spend and P2TR Reject non-SIGHASH_ALL Reject psbt v0 send to SP output

Remove MockPSBT from verify_sp_outputs Test test_sp_spend_to_labeled_change_address should sign transaction Replace _serialize_psbt with read_psbt Replace single use compute_foreign_share with generate_dleq_proof Remove unnecessary int-byte conversions in test_bip352_vectors.py

Convert validate_bip376_spend to validate_silent_payment_inputs Use accounts to validate sp spend material and mark output.is_change Introduce reusable sp_derive_path function Fix change detection issue raised by previous test hygiene commit - Signing was restored for test_sp_spend_labeled_change_detected Fix psbt exception in consider_outputs with sp change - Add apply_label_to_spend_key primitive - Match spend public key to labeled spend public key for change New tests: sp spend to non sp output sp spend rejection tests - unknown account, incorrect sp spend derivation path sp change output with foreign keys is allowed but displays warning Changed test: sp spend to label change - fix label spend key derivation, use sp input

…r multiple outputs Per BIP-375: sort by spend key then output index in ascending order for each scan key group to determine ordering of the k value - Fix compute_silent_payment_output_scripts to match spec - Update bip375_test_vectors.json to version 1.1.1

Discourage broadcasting silent payments directly from the device. The wallet coordinator should be responsible for verifying the PSBT and finalizing for broadcast. - Users can restore the default ColdCard behavior by using the Danger Zone -> SP Final Export setting. - USB API was not modified.

macgyver13 · 2026-07-29T20:41:46Z

Last force push makes the following changes:

update libngu submodule version to match PR
- reduce bech32 decode character limit to match submodule for memory efficiency
remove deadcode in dleq.py
match bip v1.1.1 bip375_test_vectors.json
add delay to stabilize test_sp_export* tests

macgyver13 mentioned this pull request Nov 26, 2025

Coldcard Silent Payments + BIP 375 Support silent-payments/roadmap#45

Open

macgyver13 force-pushed the silentpayments-bip375-psbt branch from e065256 to 4923edd Compare December 4, 2025 22:37

scgbckbone reviewed Dec 5, 2025

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Comment thread shared/bech32.py Outdated

macgyver13 force-pushed the silentpayments-bip375-psbt branch from 4923edd to c5b5977 Compare December 5, 2025 21:28

FreeOnlineUser mentioned this pull request Jan 7, 2026

[Bounty] Implement sending to Silent Payment addresses - 0.01 BTC SeedSigner/seedsigner#569

Open

nymius reviewed Jan 30, 2026

View reviewed changes

Comment thread shared/silentpayments.py Outdated

scgbckbone mentioned this pull request Mar 18, 2026

bip353 draft Coldcard/ckcc-protocol#59

Open

macgyver13 force-pushed the silentpayments-bip375-psbt branch from 2554014 to b39d529 Compare March 26, 2026 13:29

macgyver13 marked this pull request as draft March 26, 2026 13:33

macgyver13 force-pushed the silentpayments-bip375-psbt branch from b39d529 to ecbd31f Compare March 27, 2026 01:25

macgyver13 force-pushed the silentpayments-bip375-psbt branch 2 times, most recently from 9434786 to c8be414 Compare April 30, 2026 19:56

macgyver13 marked this pull request as ready for review April 30, 2026 20:28

macgyver13 changed the title ~~WIP: Add Silent Payments + BIP 375 Support~~ Add Silent Payments Support Apr 30, 2026

macgyver13 force-pushed the silentpayments-bip375-psbt branch from 5777d81 to 847108c Compare May 8, 2026 13:13

macgyver13 force-pushed the silentpayments-bip375-psbt branch from 847108c to 106990f Compare June 8, 2026 17:33

macgyver13 mentioned this pull request Jul 1, 2026

Add MuSig2 + Silent Payments #683

Draft

nit: mark bitcoind dependent sign tests

5f2db0c

macgyver13 mentioned this pull request Jul 29, 2026

Expose EC point arithmetic and add bip352_encode for Silent Payments switck/libngu#57

Open

macgyver13 added 5 commits July 29, 2026 16:19

bump submodule version

e004001

external/ckcc-protocol - Add bip375 and bip376 constants external/libngu - Expose ec_pubkey_combine - Expose ec_pubkey_tweak_mul - Add bip352_encode

BIP-352: implement Silent Payments cryptographic primitives

4be2f2d

Add bip352 crypto primitives / helpers Add bip352 tagged hashes

BIP-374: implement DLEQ proof generation and verification

e556787

Add bip374 tagged hashes Add dleq bip374 reference generate_dleq_proof, verify_dleq_proof functions

SP: add SilentPaymentsMixin

b245672

Extend psbt handling with silent payment specific functions Incorporate validation functions from bip375 test vectors - psbt_structure, input_eligibility, ecdh_coverage Add private key derivation helper functions

fix: (psbt v2) structural changes

05ada7c

Only store key_data for short_values - remove key_type Only serialize PSBT_OUT_SCRIPT if self.script has a value Adjust v2 script assert to not required if sp_v0_info is present

macgyver13 added 16 commits July 29, 2026 16:19

fix: (usb_test) Unify local and globals dict to single namespace

52720fe

Provides silent payments testing framework with access to MockPSBT

BIP-352: add test vectors

5cbf736

Add testing/test_bip352_vectors.py and testing/bip352_test_vectors.json - Verify SP sending and receiving test vectors

BIP-375: implement Silent Payments PSBT signing workflows

41d5a77

Integrate preview silent payment address as output in auth:interact Integrate silent payments in signing workflow Add sp_hrp property to chains.py Add silent payments fields to psbt.py

BIP-376: handle spending silent payments outputs

4f62e66

Add sp_spend support to _derive_input_privkey Validate bip376 spend key derivation

SP: introduce partial share contribution workflow

56a595b

Add test to validate 'Contribute Shares?' UX Simplify SP preview and signing code paths

SP: introduce UI change output validation

c63e578

Add silent payments label change tests - Detect presence or absence of 'Change back:' in UI story Add multi-signer incomplete coverage scenario tests

SP: add sp spend derivation path tests

6e6d18c

Verify SP spend path was derived from m/352h Add signature verification for taproot inputs and SP outputs

SP: add docs/silentpayments.md

22847be

SP: implement bip352 generic format export

d48f5a5

Include key-value pairs: spscan, deriv, name, xfp, key_exp in bip352 dictionary Add bip352 test block to test_export_coldcard Support 127 character limit for silent payments v0

SP: add more integration tests

1d7daa3

Mixed inputs SP spend and P2TR Reject non-SIGHASH_ALL Reject psbt v0 send to SP output

macgyver13 force-pushed the silentpayments-bip375-psbt branch from e08bd9c to 812d7c6 Compare July 29, 2026 20:33

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Add Silent Payments Support - #587

Add Silent Payments Support#587
macgyver13 wants to merge 22 commits into
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macgyver13:silentpayments-bip375-psbt

macgyver13 commented Nov 26, 2025 •

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macgyver13 commented Nov 26, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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TODOs:

Screenshots

Updated UX with - silent payment address - appended to - to address -

Contribute Shares Prompt

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macgyver13 commented Mar 27, 2026

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Testing

Targeted tests

General tests

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macgyver13 commented Nov 26, 2025 •

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