Subprotocol name: ripple-account.
Ripple nodes may connect when one or both accept the other's obligations as valuable. Connected nodes are said to be neighbours. A neighbour connection is a relationship defined by an agreement to participate in Ripple transactions as neighbours, and does not refer to the messaging connection that may exist from time to time between the neighbouring nodes' hosts, and over which the neighbour relationship takes place.
The Ripple Payment Protocol involves nodes issuing and accepting obligations of a certain value to and from their neighbours, but doesn't specify how these obligations are recorded or what the terms or limits of these obligations are. Neighbours must agree on an accounting system that will approve potential transactions and record the balance of committed transactions between them. One such system is the Ripple Account Protocol.
A neighbour connection consists of nothing other than one or more accounts between the neighbours. The minimal set of data that must be known by two neighbouring nodes in order to participate in Ripple payments is:
The JSON data structure for these core account fields is:
{
"account": {
"account-id": (string),
"account-type": (string),
"unit": (URI),
"initiator": {
"node-id": (Ripple ID),
"key": (public key data structure)
},
"partner": {
"node-id": (Ripple ID),
"key": (public key data structure)
},
}
}
The roles of initiator node and partner node are determined at account creation time, with the node making the initial account offer being deemed the initiator. These roles stay constant for the life of the account, allowing either node to change its node ID.
Account types are described below. Different account types will have various other fields in addition to the core fields listed above.
There are two primary account messages: account-request and account-set.
An account-request is to request a new account, or to request a change to one or more account fields that could not be dictated unilaterally by the requesting node. An account-request must be signed unless the request could in other circumstances be imposed unilaterally by the node receiving the request. Otherwise, the requesting node must indicate that it gives permission to make the requested changes by signing the account-request, which allows this permission to be verified at a later date. If a node receives an unsigned message that it feels ought to be signed, it should reply with a Message must be signed error. An implementation may decide to simply sign every account-request.
{
"type": "account-request",
"to": (string),
"from": (string),
"request-id": (integer),
"body": {
"account": {
"account-id": (string),
(remaining account data structure containing requested field values)
},
("note": (string))
}
}
To avoid overlap, the initiator node uses odd request IDs, and the partner node uses even request IDs. Only those account fields that contain new, non-default values, or are to be changed need to be included.
The account-set message is to confirm a new account, accept the changes requested in an account-request, or to unilaterally declare changes to account fields where permitted. While any arrangement may be negotiated between nodes by trial and error, in general, a node may unilaterally dictate values for its own node-id, routing-id, and key, as well as decreases to either node's credit limit. Credit limit increases would generally require an account-request, although when it contains an increase to the other node's limit, the request is better understood as an offer.
An account-set must always be signed.
{
"type": "account-set",
"to": (string),
"from": (string),
("request-id": (integer),)
"time": (date/time string),
"body": {
"account": {
"account-id": (string),
(remaining account data structure containing requested field values)
},
}
}
The request-id is only necessary when the account-set refers to an earlier request. In that case, the account fields must be identical to those in the earlier account-request with the same request ID.
The timestamp establishes the exact time the changes to the account fields take effect.
Account messages, other than at account-creation time, should only alter one account field at a time unless two or more fields must be altered in atomic fashion.
Accounts are established by a signed account-request message sent between potential or existing neighbours containing the basic information for the account:
Example:
{
"type": "account-request",
"to": "random",
"from": "rfugger",
"request-id": 1,
"time": "2007-04-01 15:53:41.537449",
"body": {
"account": {
"account-id": "550e8400-e29b-41d4-a716-446655440000",
"unit": "urn:ripple:units:CAD",
"external-id": "120489",
"initiator": {
"node-id": "rfugger@ripplepay.com",
"key": (...),
},
"partner": {
"node-id": "random@example.com",
}
},
"note": "Let's have an account!"
}
}
An affirmative reply means the offer has been understood being held for consideration. If the offer recipient accepts the offer, his node sends back an account-set echoing the request ID and the full account data structure in the request, as well as a timestamp which is the official account creation time.
To indicate that the account has been created, the node receiving the account-set responds with an affirmative reply. If the reply is an error, the account is not created.
Identification of Account Partner
Ripple has no universal mechanism for positively identifying the owner of another node. The owner of a node receiving a new account request should confirm the identity of the owner of the requesting node before assigning it a non-zero credit limit. Even if the node ID in the form node@host.com of the requesting node is familiar to the request recipient, one must ensure that the transport layer has verified positively by some means that the request actually comes from the correct host and that the host is trustworthy before relying solely on that piece of information.
The requesting node's owner may put secret, personal, or other information that could help the receiving node's owner identify them, such as a message signed with a personal signing key, into the note field of the account-request.
To declare a change to one or more account data fields, a node sends a signed account-set message to its account partner. An affirmative reply by the other node indicates acceptance of those changes. An error indicates rejection.
To request a change to one or more account data fields, a node sends an account-request message. An affirmative reply here only indicates that the request has been understood and is being held for approval.
Once the request is approved, the request recipient sends an account-set message echoing back the account fields and values and request ID from the account-request. An affirmative reply to the account-set completes the change.
The following errors allow nodes to negotiate between them what are permissible unilateral changes and what aren't in case of disagreement:
account-set deems requires an account-request to change in the manner requested.
account-request deems an account-set preferable for the requested change. (Equally valid is to simply accept the request immediately -- perhaps this error is unnecessary?)
To add a new data field to an account, use account-set or account-request as appropriate. If the other node does not understand the field, it will reply with an error, and the field may not be added.
An account message declaring or requesting a key change should be signed by the old key. Subsequent signed messages must be signed by the new key.
To request a copy of an account partner's account data for verification, send an account-verify-request message containing the account ID:
Example:
{
"account-verify-request": {
"account-id": "550e8400-e29b-41d4-a716-446655440000"
}
}
The immediate reply must contain the complete account data structure of the node receiving the account-verify-request as well as a timestamp:
Example:
{
"account-verify": {
"timestamp": "2006-11-07 02:11:28.401000",
"account": {
(...)
}
}
}
Neither message nor reply must be signed.
To request from an account partner a list of every signed message that has changed the value of an account field over a certain period, send an account-history-request:
Example:
{
"account-history-request": {
"starting": "2006-01-01 00:00:00.000000",
"ending": "2006-11-07 02:11:28.401000"
}
}
If the "starting" field is omitted, messages from beginning of the account should be included in the reply. If the "ending" field is omitted, messages up to the present should be included.
The reply is as follows:
{
"account-history": [
(a chronological order of signed messages sent and received over
this account during the requested period that have changed a piece
of shared account data, in the format they were originally sent or
received, including signatures)
]
}
This account history may be used as an audit to find the source of any data discrepancies between partners. This same output may also be taken for each account by a node owner from her own node in order to backup account data or move a node to a different host.
To close an account, either party may send an account-close message containing the ID of the account to be closed:
Example:
{
"account-close": {
"request-id": 14590,
"account-id": "550e8400-e29b-41d4-a716-446655440000"
}
}
An affirmative reply indicates assent to close the account. An error indicates refusal.
Ripple mutual credit accounts are electronically-kept accounts between two Ripple nodes. Both nodes keep a copy of the account data, and both share responsibility for maintaining it.
Account Data Structure
{
"account": {
"account-id": (string),
"account-type": "ripple-mutual",
"unit": (URI),
"balance": (decimal),
"initiator": {
"node-id": (Ripple ID),
"key": (public key data structure),
("limit": (decimal))
},
"partner": {
"node-id": (Ripple ID),
"key": (public key data structure)
("limit": (decimal))
},
"precision": (integer),
"interest-rate": (decimal),
"last-interest": (date/time),
"agreement": (string)
}
}
Nodes may directly set their own keys and reduce their own limits using account-set. Other modifications require an account-request to obtain the other node's approval. Balance and last-interest may only be modified by account-entry below. A change to the interest rate should be followed immediately by an account-entry settling the outstanding interest at the former rate, with an identical timestamp as the account-set that changed the interest rate.
{
"type": "account-entry",
"to": (string),
"from": (string),
"time": (date/time),
"body": {
"account-id": (string),
"entry-id": (decimal),
"amount": (decimal),
("interest": (decimal),)
}
}
entry-id is to distinguish between the entries on this account (in case an entry gets sent twice, etc.). Account initiator must use only odd entry-ids, partner must use only evens.
amount is amount that from node's balance is decreased (ie, from pays to to)
interest is interest accumulated since last-interest date, also given as amount that from node's balance is decreased. If this field is included, last-interest is set to the entry time.
precision
An account-entry must be sent when a promise is redeemed with a receipt in the payment transaction.
Extra field: "external-id": (string)
Example: bank account, where one partner (the bank) handles all the accounting in a pre-existing external mechanism.
Keys are i-WAT keys, Ripple transactions are completed using i-WAT value transfers.