lightning-keysend – Send funds to a node without an invoice

SYNOPSIS

keysend destination msatoshi [label] [maxfeepercent] [retry_for] [maxdelay] [exemptfee]

DESCRIPTION

The keysend RPC command attempts to find a route to the given destination, and send the specified amount to it. Unlike the pay RPC command the keysend command does not require an invoice, instead it uses the destination node ID, and amount to find a route to the specified node.

In order for the destination to be able to claim the payment, the payment_key is randomly generated by the sender and included in the encrypted payload for the destination. As a consequence there is not proof-of-payment, like there is with an invoice where the payment_key is generated on the destination, and the only way sender could have it is by sending a payment. Please ensure that this matches your use-case when using keysend.

destination is the 33 byte, hex-encoded, node ID of the node that the payment should go to. msatoshi is in millisatoshi precision; it can be a whole number, or a whole number with suffix msat or sat, or a three decimal point number with suffix sat, or an 1 to 11 decimal point number suffixed by btc.

The label field is used to attach a label to payments, and is returned in lightning-listpays(7) and lightning-listsendpays(7). The maxfeepercent limits the money paid in fees as percentage of the total amount that is to be transferred, and defaults to 0.5. The exemptfee option can be used for tiny payments which would be dominated by the fee leveraged by forwarding nodes. Setting exemptfee allows the maxfeepercent check to be skipped on fees that are smaller than exemptfee (default: 5000 millisatoshi).

The response will occur when the payment fails or succeeds. Unlike lightning-pay(7), issuing the same keysend commands multiple times will result in multiple payments being sent.

Until retry_for seconds passes (default: 60), the command will keep finding routes and retrying the payment. However, a payment may be delayed for up to maxdelay blocks by another node; clients should be prepared for this worst case.

When using lightning-cli, you may skip optional parameters by using null. Alternatively, use -k option to provide parameters by name.

RANDOMIZATION

To protect user privacy, the payment algorithm performs some randomization.

1: Route Randomization

Route randomization means the payment algorithm does not always use the lowest-fee or shortest route. This prevents some highly-connected node from learning all of the user payments by reducing their fees below the network average.

2: Shadow Route

Shadow route means the payment algorithm will virtually extend the route by adding delays and fees along it, making it appear to intermediate nodes that the route is longer than it actually is. This prevents intermediate nodes from reliably guessing their distance from the payee.

Route randomization will never exceed maxfeepercent of the payment. Route randomization and shadow routing will not take routes that would exceed maxdelay.

RETURN VALUE

On success, keysend will return a number of internal statistics and details of the attempts to reach the destination.

You can monitor the progress and retries of a payment using the lightning-paystatus(7) command.

The following error codes may occur:

  • -1: Catchall nonspecific error.
  • 203: Permanent failure at destination. The data field of the error will be routing failure object.
  • 205: Unable to find a route.
  • 206: Route too expensive. Either the fee or the needed total locktime for the route exceeds your maxfeepercent or maxdelay settings, respectively. The data field of the error will indicate the actual fee as well as the feepercent percentage that the fee has of the destination payment amount. It will also indicate the actual delay along the route.
  • 210: Payment timed out without a payment in progress.

A routing failure object has the fields below:

  • erring_index: The index of the node along the route that reported the error. 0 for the local node, 1 for the first hop, and so on.
  • erring_node: The hex string of the pubkey id of the node that reported the error.
  • erring_channel: The short channel ID of the channel that has the error, or 0:0:0 if the destination node raised the error.
  • failcode: The failure code, as per BOLT #4.
  • channel_update. The hex string of the channel_update message received from the remote node. Only present if error is from the remote node and the failcode has the UPDATE bit set, as per BOLT #4.

AUTHOR

Christian Decker <decker@blockstream.com> is mainly responsible.

SEE ALSO

lightning-listpays(7), lightning-decodepay(7), lightning-listinvoice(7), lightning-delinvoice(7), lightning-getroute(7), lightning-invoice(7).