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Proof of Payment in Lightning

When using the Lightning Network the data is not recorded on the Bitcoin blockchain, but still there is a cryptographic proof of payment consisting of:

  • the lightning invoice - contents signed by the recipient node
  • the pre-image - which the payer only receives when the invoice is paid.

See the Blink FAQ answers for more general details:

List invoices with proof of payment​

Requests the two most recent transactions paid via a lightning invoice (could settle over the lightning network or internally).

query PaymentsWithProof($first: Int) {
  me {
    defaultAccount {
      transactions(first: $first) {
        edges {
          node {
            initiationVia {
              ... on InitiationViaLn {
                paymentRequest
                paymentHash
              }
            }
            settlementVia {
              ... on SettlementViaIntraLedger {
                preImage
              }
              ... on SettlementViaLn {
                preImage
              }
            }
          }
        }
      }
    }
  }

Variable to show the two most recent transactions​

{
  "first": 2
}

Sample response showing the invoice, payment hash and pre-image​

{
  "data": {
    "me": {
      "defaultAccount": {
        "transactions": {
          "edges": [
            {
              "node": {
                "initiationVia": {
                  "paymentRequest": "lntbs320n1pjehuh8pp5cf6ckqv265qu6ppul0mhv4qpw4zkmd6rcxx080f8cqaz3w5p5m2qhp5ermsf933ju2t2vzpehcndlf8kpjqa780h6kzaa5eevpq6s8a7t9qcqzpuxqyz5vqsp5xs2v586kum4lu7exwskukkf0wjyw29l50293c8scdetlvszdgdds9qyyssqgzxzle9hz6384qt8uzh74wy3ylp6g3yw74q06zelxuhxtgwk9ehxvgtmqh53furqceecm22jsv2aypcangdn2tayl0vl095qx0wh3hqpwrfl8j",
                  "paymentHash": "c2758b018ad501cd043cfbf776540175456db743c18cf3bd27c03a28ba81a6d4"
                },
                "settlementVia": {
                  "preImage": "9e92a2d24e89c92c93d2c63ffe126605bcd3bf614c727a1f6e3f52064b83c2ec"
                }
              }
            },
            {
              "node": {
                "initiationVia": {
                  "paymentRequest": "lntbs10n1pjehukhpp57ngk3ddxtmytqdzcyqa4l2e87ny29rwjsqx46g6m0pvpj7tvp6vshp5at629lcgdgt53gsapw77s59ykxxn7lkxyfk4n7zdx78c65s9502scqzpuxqyz5vqsp5nru4r9hu7asuvn86euyuskzdppl3lt4xue5wl8jxawaxc5rmzynq9qyyssq4c0d6lmszx6udlw8elv6dcawlsu7069fqd60wc4xxc3v6h5lmag45f8ks9lrdwnajysc0ka3lmgchfwrjjlgx4a8dg8g7gjlqaezecgqn706p3",
                  "paymentHash": "f4d168b5a65ec8b03458203b5fab27f4c8a28dd2800d5d235b785819796c0e99"
                },
                "settlementVia": {
                  "preImage": "f3a2290961be4b91bb230cfe7ae9d8159667dd9da33ca95b7c609bf82034285c"
                }
              }
            }
          ]
        }
      }
    }
  }
}

Verify the proof of payment​

Decode the invoice​

The invoice can be used to identify the destination node, obtain the payment hash and analyze other contents by decoding it for example in:

Verify the pre-image​

The payment hash is the sha256 hash of the binary form of the preimage which can be verified in:

  • dev.blink.sv/decode

  • or in linux terminal:

    $ echo -n '<preimage_in_hex>'| xxd -r -p | sha256sum

To use the preimage as a proof of payment the calculated hash must match the payment hash in the invoice.

tip

To test the GraphQL requests further use the GraphQL playground at api.blink.sv/graphql for mainnet or api.staging.blink.sv/graphql for staging.
Check out the Galoy API Postman collection to find examples in multiple programming languages.