Overview

An invoice is a request for payment on the Lightning Network. Invoices include the information necessary to complete a payment on the network, such as payment amount, which blockchain the invoice applies to, expiry date, payee pubkey, routing hints, and other information. Invoices are used to make payments on the Lightning Network, rather than using Bitcoin-style addresses.

Invoices are commonly presented as alphanumerical strings or QR codes. In order to parse specific information from the request string, users can pass the string into a decoding tool:

• ​https://ion.radar.tech/developers#decode​

• ​https://lightningdecoder.com/​

• ​https://lndecode.com/​

Invoice Components

Every Lightning invoice requires the following information in order to be valid:

• destination: The public key of the person receiving the LN payment.

• payment_hash: The hash of the preimage that is used to lock the payment. You can only redeem a locked payment with the corresponding preimage to the payment hash. This enables routing on the Lightning Network without trusted third parties.

• num_satoshis: The amount of satoshis to be paid.

• expiry: Time when your node marks the invoice as invalid. Default is 1 hour or 3600 seconds.

• timestamp: Time when the invoice was created. This is measured in seconds since 1970.

• cltv_expiry: Delta to use for time-lock of CLTV extended to the final hop.

Convert timestamps to regular human time: https://www.epochconverter.com/​

Example Invoice

Below is a sample invoice decoded using an invoice decoding tool. The standard fields included are:

{
    "human_readable_part": {
        "prefix": "lntb",
        "amount": 1000000000
    },
    "data": {
        "time_stamp": 1547508400,
        "tags": [
            {
                "type": "p",
                "length": 52,
                "description": "payment_hash",
                "value": "f0ce4a761f04c7bef42fc323cca4850f317c62421e69654fea4d605e70c339b2"
            },
            {
                "type": "d",
                "length": 0,
                "description": "description",
                "value": ""
            },
            {
                "type": "c",
                "length": 2,
                "description": "min_final_cltv_expiry",
                "value": 144
            },
            {
                "type": "x",
                "length": 2,
                "description": "expiry",
                "value": 600
            }
        ],
        "signature": {
            "r": "ac2080f2caf03309b7267c27dd663185a4074b94836a46e02fdcc585c19c02a3",
            "s": "09416f765bf3167a03d92d6dbeef19ebcba168b940228c8d5896ea137769798c",
            "recovery_flag": 0
        },
        "signing_data": "6c6e746231306d0b87a356010d3c33929d87c131efbd0bf0c8f3292143cc5f1890879a5953fa9358179c30ce6c81a006002240c014b0"
    },
    "checksum": "nvhulk"
}

References

1. ​BOLT #11 standards document

2. ​Lightning Payment Request Decoder app

3. ​Radar ION Invoice Decoder​

4. ​Lightning Decoder app

5. ​"Lightning Network Invoices" , Blockfuse (2018-12-08)