PayChannel

[Source]

(Requires the PayChan Amendment.)

The PayChannel object type represents a payment channel. Payment channels enable small, rapid off-ledger payments of XRP that can be later reconciled with the consensus ledger. A payment channel holds a balance of XRP that can only be paid out to a specific destination address until the channel is closed. Any unspent XRP is returned to the channel's owner (the source address that created and funded it) when the channel closes.

The PaymentChannelCreate transaction type creates a PayChannel object. The PaymentChannelFund and PaymentChannelClaim transaction types modify existing PayChannel objects.

When a payment channel expires, at first it remains on the ledger, because only new transactions can modify ledger contents. Transaction processing automatically closes a payment channel when any transaction accesses it after the expiration. To close an expired channel and return the unspent XRP to the owner, some address must send a new PaymentChannelClaim or PaymentChannelFund transaction accessing the channel.

For an example of using payment channels, see the Payment Channels Tutorial.

Example PayChannel JSON

{
    "Account": "rBqb89MRQJnMPq8wTwEbtz4kvxrEDfcYvt",
    "Destination": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
    "Amount": "4325800",
    "Balance": "2323423",
    "PublicKey": "32D2471DB72B27E3310F355BB33E339BF26F8392D5A93D3BC0FC3B566612DA0F0A",
    "SettleDelay": 3600,
    "Expiration": 536027313,
    "CancelAfter": 536891313,
    "SourceTag": 0,
    "DestinationTag": 1002341,
    "Flags": 0,
    "LedgerEntryType": "PayChannel",
    "OwnerNode": "0000000000000000",
    "PreviousTxnID": "F0AB71E777B2DA54B86231E19B82554EF1F8211F92ECA473121C655BFC5329BF",
    "PreviousTxnLgrSeq": 14524914,
    "index": "96F76F27D8A327FC48753167EC04A46AA0E382E6F57F32FD12274144D00F1797"
}

PayChannel Fields

A PayChannel object has the following fields:

Name JSON Type Internal Type Description
LedgerEntryType String UInt16 The value 0x0078, mapped to the string PayChannel, indicates that this object is a payment channel object.
Account String AccountID The source address that owns this payment channel. This comes from the sending address of the transaction that created the channel.
Destination String AccountID The destination address for this payment channel. While the payment channel is open, this address is the only one that can receive XRP from the channel. This comes from the Destination field of the transaction that created the channel.
Amount String Amount Total XRP, in drops, that has been allocated to this channel. This includes XRP that has been paid to the destination address. This is initially set by the transaction that created the channel and can be increased if the source address sends a PaymentChannelFund transaction.
Balance String Amount Total XRP, in drops, already paid out by the channel. The difference between this value and the Amount field is how much XRP can still be paid to the destination address with PaymentChannelClaim transactions. If the channel closes, the remaining difference is returned to the source address.
PublicKey String PubKey Public key, in hexadecimal, of the key pair that can be used to sign claims against this channel. This can be any valid secp256k1 or Ed25519 public key. This is set by the transaction that created the channel and must match the public key used in claims against the channel. The channel source address can also send XRP from this channel to the destination without signed claims.
SettleDelay Number UInt32 Number of seconds the source address must wait to close the channel if it still has any XRP in it. Smaller values mean that the destination address has less time to redeem any outstanding claims after the source address requests to close the channel. Can be any value that fits in a 32-bit unsigned integer (0 to 2^32-1). This is set by the transaction that creates the channel.
OwnerNode String UInt64 A hint indicating which page of the source address's owner directory links to this object, in case the directory consists of multiple pages.
PreviousTxnID String Hash256 The identifying hash of the transaction that most recently modified this object.
PreviousTxnLgrSeq Number UInt32 The index of the ledger that contains the transaction that most recently modified this object.
Flags Number UInt32 A bit-map of boolean flags enabled for this payment channel. Currently, the protocol defines no flags for PayChannel objects.
Expiration Number UInt32 (Optional) The mutable expiration time for this payment channel, in seconds since the Ripple Epoch. The channel is expired if this value is present and smaller than the previous ledger's close_time field. See Setting Channel Expiration for more details.
CancelAfter Number UInt32 (Optional) The immutable expiration time for this payment channel, in seconds since the Ripple Epoch. This channel is expired if this value is present and smaller than the previous ledger's close_time field. This is optionally set by the transaction that created the channel, and cannot be changed.
SourceTag Number UInt32 (Optional) An arbitrary tag to further specify the source for this payment channel, such as a hosted recipient at the owner's address.
DestinationTag Number UInt32 (Optional) An arbitrary tag to further specify the destination for this payment channel, such as a hosted recipient at the destination address.

Setting Channel Expiration

The Expiration field of a payment channel is the mutable expiration time, in contrast to the immutable expiration time represented by the CancelAfter field. The expiration of a channel is always considered relative to the close_time field of the previous ledger. The Expiration field is omitted when a PayChannel object is created. There are several ways the Expiration field of a PayChannel object can be updated, which can be summarized as follows: a channel's source address can set the Expiration of the channel freely as long as the channel always remains open at least SettleDelay seconds after the first attempt to close it.

Source Address

The source address can set the Expiration directly with the PaymentChannelFund transaction type. The new value must not be earlier than whichever of the following values is earliest:

  • The current Expiration value (if one is set)
  • The previous ledger's close time plus the SettleDelay of the channel

In other words, the source address can always make the Expiration later if an expiration is already set. The source can make an Expiration value earlier or set an Expiration if one isn't currently set, as long as the new value is at least SettleDelay seconds in the future. If the source address attempts to set an invalid Expiration date, the transaction fails with the temBAD_EXPIRATION error code.

The source address can also set the Expiration with the tfClose flag of the PaymentChannelClaim transaction type. If the flag is enabled, the ledger automatically sets the Expiration to whichever of the following values is earlier:

  • The current Expiration value (if one is set)
  • The previous ledger's close time plus the SettleDelay of the channel

The source address can remove the Expiration with the tfRenew flag of the PaymentChannelClaim transaction type.

Destination Address

The destination address cannot set the Expiration field. However, the destination address can use the PaymentChannelClaim's tfClose flag to close a channel immediately.

Other Addresses

If any other address attempts to set an Expiration field, the transaction fails with the tecNO_PERMISSION error code. However, if the channel is already expired, the transaction causes the channel to close and results in tesSUCCESS instead.

PayChannel ID Format

The ID of a PayChannel object is the SHA-512Half of the following values, concatenated in order:

  • The PayChannel space key (0x0078)
  • The AccountID of the source account
  • The AccountID of the destination account
  • The Sequence number of the transaction that created the channel