發票格式

BOLT 11 Invoice Example:

lnbc1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqdpl
2pkx2ctnv5sxxmmwwd5kgetjypeh2ursdae8g6twvus8g6rfwvs8qun0dfjkxaq8rkx3yf5
tcsyz3d73gafnh3cax9rn449d9p5uxz9ezhhypd0elx87sjle52x86fux2ypatgddc6k63n
7erqz25le42c4u4ecky03ylcqca784w

Structure:
lnbc    - prefix (mainnet)
1       - amount (optional)
p...    - tagged data
8rkx... - signature

BOLT 11 Invoice Structure:

Prefix:
  ln + network:
  • lnbc  - Bitcoin mainnet
  • lntb  - testnet
  • lnbcrt - regtest
  • lnsb  - signet

Amount (optional):
  number + multiplier:
  • m = milli (0.001)
  • u = micro (0.000001)
  • n = nano (0.000000001)
  • p = pico (0.000000000001)
  Example: 2500u = 2500 micro = 250000 sats

Timestamp:
  Invoice creation time (UNIX seconds)

Tagged Fields:
  Various payment info...

Signature:
  Receiver node signature

Tagged Field Format:
type (5 bits) + data_length (10 bits) + data

Common Tags:

p (1): payment_hash (52 chars, 256 bits)
       SHA256 payment hash, required

s (16): payment_secret (52 chars, 256 bits)
        prevents probing attacks

d (13): description (variable)
        UTF-8 description text

h (23): description_hash (52 chars)
        hash of long description

x (6): expiry (variable)
       expiry seconds, default 3600 (1 hour)

c (24): min_final_cltv_expiry (variable)
        minimum CLTV delta, default 18

n (19): payee node_id (53 chars)
        receiver pubkey (recoverable from sig)

r (3): routing hint
       private channel routing info

f (9): fallback address
       on-chain fallback address

9 (5): feature bits
       supported features

Routing Hint Structure (r tag):

Each hint contains one channel:
├── pubkey (33 bytes): entry node pubkey
├── short_channel_id (8 bytes)
├── fee_base_msat (4 bytes)
├── fee_proportional_millionths (4 bytes)
└── cltv_expiry_delta (2 bytes)

Example scenario:
Carol only has private channel to Bob

Invoice includes hint:
r = [
  {
    pubkey: Bob's pubkey,
    short_channel_id: Bob-Carol channel,
    fee: ...,
    cltv: ...
  }
]

Sender routing:
Alice -> ... -> Bob -> Carol (private channel)

Decode Example (using lncli):

$ lncli decodepayreq lnbc...

{
  "destination": "03...公鑰",
  "payment_hash": "0001020304...",
  "num_satoshis": "100000",
  "timestamp": "1609459200",
  "expiry": "3600",
  "description": "Coffee payment",
  "cltv_expiry": "18",
  "features": {
    "9": { "name": "tlv-onion" },
    "14": { "name": "payment-addr" },
    "17": { "name": "multi-path-payments" }
  },
  "payment_addr": "abcd..."
}

BOLT 12 Core Concepts:

Offer:
• Reusable payment request template
• Like a "donation link"
• No payment_hash (generated per request)

lno1qcp4256ypq...

Flow:
1. Merchant publishes Offer
2. Payer sends invoice_request (via onion message)
3. Merchant responds with invoice (with payment_hash)
4. Payer pays

Advantages:
• Reusable (subscriptions, donations)
• Supports refunds (refund message)
• Enhanced privacy (receiver can use blinded paths)
• No centralized server needed

Offer TLV Fields:

offer_chains (2): supported blockchains
offer_metadata (4): merchant custom data
offer_currency (6): currency code (e.g. USD)
offer_amount (8): amount (for fiat pricing)
offer_description (10): description
offer_features (12): feature bits
offer_absolute_expiry (14): absolute expiry time
offer_paths (16): blinded paths
offer_issuer (18): issuer name
offer_quantity_max (20): max quantity
offer_node_id (22): node ID

invoice_request Additional Fields:
invreq_metadata (0): requester data
invreq_chain (80): selected chain
invreq_amount (82): payment amount
invreq_features (84): features
invreq_quantity (86): quantity
invreq_payer_id (88): payer ephemeral pubkey
invreq_payer_note (89): payer note

Refund Flow:

1. Original Payment
   Payer -> Merchant (pay invoice)

2. Refund Request
   Merchant creates refund (like reverse offer)
   Sends to original payer

3. Refund Invoice
   Payer sends invoice_request
   Merchant responds with invoice

4. Refund Payment
   Merchant pays invoice

Refund TLV:
refund_for: original payment_hash
refund_amount: refund amount

BOLT 12 Privacy Features:

1. Blinded Paths
   • Offer can include blinded paths
   • Payer cannot identify receiver's real node
   • Suitable for anonymous donations

2. Onion Messages
   • invoice_request sent via onion network
   • No direct connection to receiver needed

3. Payer Ephemeral Identity
   • Each request uses new payer_id
   • Does not reveal payer's real node ID

4. No payment_hash Correlation
   • Each payment uses new hash
   • Cannot correlate multiple payments to same offer