[New Feature] Add BIP-353 support #102

alvroble · 2025-08-05T16:29:02Z

This PR implements BIP-353 "DNS Payment Instructions" for embit, enabling Bitcoin payments to human-readable names (HRNs) with offline DNSSEC validation capabilities.

Resolves #85
Related SeedSigner/seedsigner#768

Overview

BIP-353 allows Bitcoin payments to be directed to human-readable names instead of cryptographic addresses, using DNSSEC proofs for secure verification. This implementation provides complete infrastructure for BIP-353 compliance, including offline validation support for hardware wallet integration.

Related Work

This implementation leverages @TheBlueMatt's dnssec-prover Rust tool for offline DNSSEC validation. The tool has been cross-compiled and integrated with Python bindings for embit integration.

Implementation Details

PSBT field

Added PSBT_OUT_DNSSEC_PROOF field to embed DNSSEC proofs in PSBT outputs. This enables wallets to include DNSSEC validation for the payment destination, allowing offline verification of the transaction.

Noticed there's an overlap here with #101. The implementation approach is quite similar. I had committed this change a few weeks ago but only just got around to publishing it. To avoid conflicts, we might want to consolidate both efforts or drop one of the overlapping changes. Open to suggestions on how best to proceed.

`dnssec-prover` integration

Integrated dnssec-prover tool with Python bindings for cross-platform support. The prebuilt binaries and bindings were generated by using uniffi on the main dnssec-prover branch.

Added for the same set of platforms as secp256k1. Tested on macOS and Raspberry Pi 3B. Additional testing is needed for more SeedSigner platforms and MicroPython environments.

BIP-353 implementation

The core implementation provides two main functions:

verify_dns_proof() - Validates DNSSEC proofs and extracts TXT records
get_payment_info_from_hrn() - Extracts complete payment information from HRNs

The implementation filters to only process TXT records (as required by BIP-353) and supports both regular Bitcoin addresses and silent payment addresses.

Added test vectors from Sparrow Wallet's implementation.

BIP-21 URI support

Added complete BIP-21 URI scheme implementation to parse Bitcoin URIs from DNS TXT records. This handles all standard Bitcoin URI parameters including amounts, labels, messages, and silent payment addresses.

Considerations

Additional testing is needed for SeedSigner platforms and MicroPython environments.
An alternative approach would be to use pydnssec-prover Python library which is a port from dnssec-prover. Main benefit would be not having to rely on prebuilt binaries. On the other hand, that library is recent and not as tested as dnssec-prover.

References

* Generated with uniffi with cross-compilation from macOS

notTanveer · 2025-08-06T11:32:56Z

src/embit/bip353.py

+
+    # Extract the Bitcoin URI from the verified TXT DNS records only
+    verified_rrs = result.get("verified_rrs", [])
+    txt_records = [rr for rr in verified_rrs if rr.get("type") == "txt"]


filtering verified_rrs for TXT records is redundant since verify_dns_proof already filters to only TXT records.

Huh, didn't notice... thanks for the heads up!

I don't believe it does, though an HRN proof in a PSBT generally shouldn't be proving other records :)

src/embit/bip353.py

notTanveer · 2025-08-06T11:43:10Z

src/embit/bip353.py

+
+    # Validate that at least one payment method is available
+    has_regular_address = payment_info["address"] is not None
+    has_silent_payment = payment_info["silent_payment_address"] is not None


not sure this belongs here, given that sending silent payments isn’t supported yet. should we just leave a TODO for now?

notTanveer · 2025-08-06T12:05:05Z

src/embit/bip21.py

+            except (InvalidOperation, ValueError, OverflowError) as e:
+                raise BIP21Error(f"'{value}' is not a valid amount: {e}")
+
+        elif name == self.FIELD_SILENT_PAYMENT and value:


embit still lacks support for sending silent payments and doesn't handle decoding of large payloads. i'm wondering what happens if a dns instruction contains only a silent payment address.

also, this code ain't decoding the sp addresses properly. i think we should think this through carefully before adding this here. incomplete validation might be worse than no validation at all. maybe we can leave a TODO for now(?)

I partially agree with you. I should remove those decoding conditions I set completely arbitrarily. But would it hurt to enable DNS record validation for SP? I would say no, at least we should add minimal support. If we don’t add any support and we receive a DNS record with an SP address, should we raise an error? I think that may be overkill, as it’s not directly related to DNSSEC validation.

as far as validation goes, i don’t think it’s harmful—but the point i’m trying to make is that if we try to send to a silent payment address, it’s going to fail anyway since there’s no support for it yet.

that said, if you’d like to keep the validation, i’d suggest adding a test vector in test_bip21.py to go along with it.

Let's see what others devs think. What we have now is mostly a hybrid BIP-21/BIP-321 implementation for the URI without all the Lightning stuff. Maybe it makes sense to also ignore the SP stuff as you propose.

src/embit/bip21.py

* enabled multiple bc and sp queries as per BIP321 draft * internally manage "bitcoin:<address>" with no explicit field

tests/tests/test_bip353.py

alvroble · 2025-08-07T10:45:47Z

BIP21 replacement by BIP321 is being proposed in bitcoin/bips#1911. Maybe it makes sense to go full BIP321 compatible?

TheBlueMatt · 2025-08-07T11:44:25Z

I think this is BIP 321 compatible already?

alvroble · 2025-08-07T11:47:03Z

Yes, if we leave aside the Lightning elements

TheBlueMatt · 2025-08-07T11:53:50Z

src/embit/bip353.py

+
+    # Extract the Bitcoin URI from the verified TXT DNS records only
+    verified_rrs = result.get("verified_rrs", [])
+    txt_records = [rr for rr in verified_rrs if rr.get("type") == "txt"]


I don't believe it does, though an HRN proof in a PSBT generally shouldn't be proving other records :)

src/embit/bip353.py

TheBlueMatt · 2025-08-07T11:54:54Z

BIP 321 doesn't require you to implement lightning, if its confusing anywhere and implies that let me know.

kdmukai · 2025-08-08T15:53:52Z

It would help my end-to-end testing if someone could create or point me to a DNS entry that resolves to a testnet addr.

*Allow multiple TXT records in DNSSEC proof per BIP353 specification *Only one TXT record can start with "bitcoin:" (case insensitive) *Add validation from bitcoin/bips#1912

alvroble · 2025-08-08T16:54:51Z

@kdmukai try with test@alvroble.com

kdmukai · 2025-08-10T14:03:59Z

src/embit/bip353.py

+    except Exception as e:
+        return {"error": f"DNSSEC proof verification failed for HRN '{hrn}': {e}"}


I haven't reviewed the exception convention in embit, but my first instinct here is to define a specific Exception (e.g. something like DNSSECProofValidationFailureException).

Also is there any diversity of exception types that might get thrown by the library call?

From dnssec_prover.py, I think only InternalError applies, which is more related to the Rust FFI that to the actual functionality. No other specific error applies from the generated bindings file perspective.

kdmukai · 2025-08-10T14:16:15Z

The main README should be updated to explain the new binaries. I think there should also be some documentation (maybe in a separate doc) about how the binaries were made and how to reproduce them, links to the rust repo, etc.

src/embit/bip21.py

- Add comprehensive build instructions for reproducing dnssec-prover binaries - Include reproducible build hashes for verification - Added binaries that can be reproduced and hash-attested - Update main README to reference dnssec-prover binaries

alvroble · 2025-08-15T14:28:10Z

Added reproducible build instructions for dnssec-prover and updated README. Uploaded hash-attested binaries. Please test to confirm everything builds correctly.

alvroble added 4 commits July 5, 2025 10:56

add bip353 psbt fields

5f967e5

Add binaries and bindings for dnssec-prover

1e82388

* Generated with uniffi with cross-compilation from macOS

Add bip21 support

889d76d

Add bip353 support

352709f

alvroble mentioned this pull request Aug 6, 2025

[Feature] Add BIP-353 proof validation SeedSigner/seedsigner#768

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notTanveer mentioned this pull request Aug 6, 2025

BIP-353 DNSSEC proof support to PSBT #101

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notTanveer reviewed Aug 6, 2025

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alvroble added 4 commits August 6, 2025 18:58

Refactored TXT rrs filtering and exception handling

c31e4ac

Add bc field and better handling for uri address

0733ecb

* enabled multiple bc and sp queries as per BIP321 draft * internally manage "bitcoin:<address>" with no explicit field

bugfixes

1b6fb2a

Added BIP321 test vectors for consistency

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notTanveer reviewed Aug 7, 2025

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Added invalid proof test vector

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TheBlueMatt reviewed Aug 7, 2025

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alvroble added 2 commits August 8, 2025 18:06

Allow multiple TXT records but only one URI

f2ac62e

*Allow multiple TXT records in DNSSEC proof per BIP353 specification *Only one TXT record can start with "bitcoin:" (case insensitive) *Add validation from bitcoin/bips#1912

Move BIP-353 field at the end of read_value()

e5cc856

Bicaru20 mentioned this pull request Aug 8, 2025

[Feature] Add BIP-353 proof validation SeedSigner/seedsigner#798

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alvroble added 4 commits August 11, 2025 17:38

Better Exception management for BIP353

c983823

Code refactor and type hints

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Fail for amount with sub-satoshi values

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alvroble mentioned this pull request Sep 2, 2025

SeedSigner + BIP-353: Human-Readable Bitcoin Payments TABConf/7.tabconf.com#63

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		except Exception as e:
		return {"error": f"DNSSEC proof verification failed for HRN '{hrn}': {e}"}

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Overview

Related Work

Implementation Details

PSBT field

dnssec-prover integration

BIP-353 implementation

BIP-21 URI support

Considerations

References

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alvroble commented Aug 5, 2025 •

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`dnssec-prover` integration

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