BOLT 12: first draft of payer proofs #1295
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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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jkczyz
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Nov 11, 2025
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Some minor comments from a first pass. Should have more feedback once we attempt to implement this.
| * [`bip340sig`:`sig`] | ||
| 1. type: 242 (`preimage`) | ||
| 2. data: | ||
| * [`32*byte`:`premage`] |
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| The non-signature elements of a payer proof are identical to the | ||
| `invoice` tlv_stream, with the exception that `invreq_metadata` cannot | ||
| be included. Various fields are omitted for privacy: numbers |
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| A writer of a payer_proof: | ||
| - MUST NOT include `invreq_metadata`. | ||
| - MUST include `invreq_payer_id`, `invoice_payment_hash`, `invoice_node_id`, `signature` and (if present) `invoice_features` from the invoice. |
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Could you include a rationale for requiring invoice_features?
| - `omitted_tlvs` contains 0. | ||
| - `omitted_tlvs` contains signature TLV element number (240 through 1000 inclusive). | ||
| - `omitted_tlvs` contains the number of an included TLV field. | ||
| - `omitted_tlvs` contains more than one number larger than the largest included non-signature TLV element. |
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Not sure I understand this restriction. Why can't more than one such TLV be omitted? The example contradicts this (41 and 42), IIUC.
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Oops, this was from an earlier draft, and should be removed!
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| Note that the signature TLV 250 is not included in the merkle tree. | ||
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| `leaf_hashes` contains the nonce hashes for the present non-signature TLVS: |
| 1. type: 250 (`payer_signature`) | ||
| 2. data: | ||
| * [`bip340sig`:`sig`] | ||
| * [`...*utf8`:`note`] |
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Presumably, this may be empty?
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This was referenced Dec 10, 2025
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vincenzopalazzo
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Jan 2, 2026
Implements the payer proof extension to BOLT 12 as specified in lightning/bolts#1295. This allows proving that a BOLT 12 invoice was paid by demonstrating possession of the payment preimage, a valid invoice signature, and a payer signature. Key additions: - Extend merkle.rs with selective disclosure primitives for creating and reconstructing merkle trees with partial TLV disclosure - Add payer_proof.rs with PayerProof, PayerProofBuilder, and UnsignedPayerProof types for building and verifying payer proofs - Support bech32 encoding with "lnp" prefix 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Thanks for this spec! I am finishing to implement it in ldk and have some feedback from implementation experience:
- The nonce hash notation needs clarification (see inline comment)
- Test vectors would be extremely valuable for cross-implementation compatibility. Wondering if you already had some draft implementation where we can compare the tests vectors?
Happy to provide my implementation's test vectors once the ambiguities are resolved.
| - For each non-signature TLV in the invoice in ascending-type order: | ||
| - If the field is to be included in the payer_proof: | ||
| - MUST copy it into the payer_proof. | ||
| - MUST append the nonce (H("LnNonce"||TLV0,type)) to `leaf_hashes`. |
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nit: is ambiguous. It could mean:
- H(H("LnNonce"||TLV0) || H("LnNonce"||TLV0) || type) (tagged hash style), or
- H("LnNonce" || TLV0 || type) (simple concatenation)
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| Thus, `missing_hashes` contains the following hashes in left-to-right | ||
| order: | ||
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| 1. Merkle of H("LnLeaf",TLV0) and H("LnNonce"||TLV0,0) | ||
| 2. Merkle of (Merkle of H("LnLeaf",TLV20) and H("LnNonce"||TLV0,20)) | ||
| and (Merkle of H("LnLeaf",TLV30) and H("LnNonce"||TLV0,30)) | ||
| 3. Merkle of H("LnLeaf",TLV50) and H("LnNonce"||TLV0,50) |
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The example shows only 3 missing_hashes but TLV 60 is also omitted.
Looking at the tree, when the subtree (40, [50]) combines with [60] at level 2, shouldn't we need a 4th hash for 60?
Am I misunderstanding the tree structure, or is this example incomplete?
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Implements the payer proof extension to BOLT 12 as specified in lightning/bolts#1295. This allows proving that a BOLT 12 invoice was paid by demonstrating possession of the payment preimage, a valid invoice signature, and a payer signature. Key additions: - Extend merkle.rs with selective disclosure primitives for creating and reconstructing merkle trees with partial TLV disclosure - Add payer_proof.rs with PayerProof, PayerProofBuilder, and UnsignedPayerProof types for building and verifying payer proofs - Support bech32 encoding with "lnp" prefix
vincenzopalazzo
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Jan 4, 2026
Implements the payer proof extension to BOLT 12 as specified in lightning/bolts#1295. This allows proving that a BOLT 12 invoice was paid by demonstrating possession of the payment preimage, a valid invoice signature, and a payer signature. Key additions: - Extend merkle.rs with selective disclosure primitives for creating and reconstructing merkle trees with partial TLV disclosure - Add payer_proof.rs with PayerProof, PayerProofBuilder, and UnsignedPayerProof types for building and verifying payer proofs - Support bech32 encoding with "lnp" prefix
vincenzopalazzo
added a commit
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Jan 4, 2026
Implements the payer proof extension to BOLT 12 as specified in lightning/bolts#1295. This allows proving that a BOLT 12 invoice was paid by demonstrating possession of the payment preimage, a valid invoice signature, and a payer signature. Key additions: - Extend merkle.rs with selective disclosure primitives for creating and reconstructing merkle trees with partial TLV disclosure - Add payer_proof.rs with PayerProof, PayerProofBuilder, and UnsignedPayerProof types for building and verifying payer proofs - Support bech32 encoding with "lnp" prefix
vincenzopalazzo
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Jan 5, 2026
Implements the payer proof extension to BOLT 12 as specified in lightning/bolts#1295. This allows proving that a BOLT 12 invoice was paid by demonstrating possession of the payment preimage, a valid invoice signature, and a payer signature. Key additions: - Extend merkle.rs with selective disclosure primitives for creating and reconstructing merkle trees with partial TLV disclosure - Add payer_proof.rs with PayerProof, PayerProofBuilder, and UnsignedPayerProof types for building and verifying payer proofs - Support bech32 encoding with "lnp" prefix
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