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README.md

    
Title:        Single Asset Tokenized Vault
Revision:     1 (2025-02-05)


Authors:    
  Vytautas Vito Tumas
  Aanchal Malhotra

Affiliation:
  Ripple

Single Asset Vault

Abstract

A Single Asset Vault is a new on-chain primitive for aggregating assets from one or more depositors, and making the assets available for other on-chain protocols. The Single Asset Vault uses Multi-Purpose-Token to represent ownership shares of the Vault. The Vault serves diverse purposes, such as lending markets, aggregators, yield-bearing tokens, asset management, etc. The Single Asset Vault decouples the liquidity provision functionality from the specific protocol logic.

Index

1. Introduction

1.1 Overview

The Single Asset Vault is an on-chain object that aggregates assets from one or more depositors and represents ownership through shares. Other protocols, such as the Lending Protocol, can access these assets via the vault, whether or not they generate yield. Currently, other protocols must be created by the same Account that created the Vault. However, this may change in the future.

The specification introduces a new Vault ledger entry, which contains key details such as available assets, shares, total value, and other relevant information.

The specification includes the following transactions:

Vault Management:

  • VaultCreate: Creates a new Vault object.
  • VaultSet: Updates an existing Vault object.
  • VaultDelete: Deletes an existing Vault object.

Asset Management:

  • VaultDeposit: Deposits a specified number of assets into the Vault in exchange for shares.
  • VaultWithdraw: Withdraws a specified number of assets from the Vault in exchange for shares.

Additionally, an issuer can perform a Clawback operation:

  • VaultClawback: Allows the issuer of an IOU or MPT to claw back funds from the vault, as outlined in the Clawback documentation.

1.1.1 Vault Ownership and Management

A Single Asset Vault is owned and managed by an account called the Vault Owner. The account is reponsible for creating, updating and deleting the Vault object.

1.1.2 Access Control

A Single Asset Vault can be either public or private. Any depositor can deposit and redeem liquidity from a public vault, provided they own sufficient shares. In contrast, access to private shares is controlled via Permissioned Domains, which use on-chain Credentials to manage access to the vault. Only depositors with the necessary credentials can deposit assets to a private vault. To prevent Vault Owner from locking away depositor funds, any shareholder can withdraw funds. Furthermore, the Vault Owner has an implicit permission to deposit and withdraw assets to and from the Vault. I.e. they do not have to have credentials in the Permissioned Domain.

1.1.3 Yield Bearing Shares

Shares represent the ownership of a portion of the vault's assets. On-chain shares are represented by a Multi-Purpose Token. When creating the vault, the Vault Owner can configure the shares to be non-transferable. Non-transferable shares cannot be transferred to any other account -- they can only be redeemed. If the vault is private, shares can be transferred and used in other DeFi protocols as long as the receiving account is authorized to hold the shares. The vault's shares may be yield-bearing, depending on the protocol connected to the vault, meaning that a holder may be able to withdraw more (or less) liquidity than they initially deposited.

1.2 Terminology

  • Vault: A ledger entry for aggregating liquidity and providing this liquidity to one or more accessors.
  • Asset: The currency of a vault. It is either XRP, a Fungible Token or a Multi-Purpose Token.
  • Share: Shares represent the depositors' portion of the vault's assets. Shares are a Multi-Purpose Token created by the pseudo-account of the vault.

1.3 Actors

  • Vault Owner: An account responsible for creating and deleting The Vault.
  • Depositor: An entity that deposits and withdraws assets to and from the vault.

1.4 Connecting to the Vault

A protocol connecting to a Vault must track its debt. Furthermore, the updates to the Vault state when funds are removed or added back must be handled in the transactors of the protocol. For an example, please refer to the Lending Protocol specification.

Return to Index

2. Ledger Entries

2.1 Vault Ledger Entry

The Vault ledger entry describes the state of the tokenized vault.

2.1.1 Object Identifier

The key of the Vault object is the result of SHA512-Half of the following values concatenated in order:

2.1.2 Fields

A vault has the following fields:

Field Name Modifiable? Required? JSON Type Internal Type Default Value Description
LedgerEntryType N/A ✔️ string UINT16 0x0081 Ledger object type.
LedgerIndex N/A ✔️ string UINT16 N/A Ledger object identifier.
Flags Yes ✔️ string UINT32 0 Ledger object flags.
PreviousTxnID N/A ✔️ string HASH256 N/A Identifies the transaction ID that most recently modified this object.
PreviousTxnLgrSeq N/A ✔️ number UINT32 N/A The sequence of the ledger that contains the transaction that most recently modified this object.
Sequence N/A ✔️ number UINT32 N/A The transaction sequence number that created the vault.
OwnerNode N/A ✔️ number UINT64 N/A Identifies the page where this item is referenced in the owner's directory.
Owner No ✔️ string AccountID N/A The account address of the Vault Owner.
Account N/A ✔️ string ACCOUNTID N/A The address of the Vaults pseudo-account.
Data Yes string BLOB None Arbitrary metadata about the Vault. Limited to 256 bytes.
Asset No ✔️ string or object ISSUE N/A The asset of the vault. The vault supports XRP, IOU and MPT.
AssetTotal N/A ✔️ number NUMBER 0 The total value of the vault.
AssetAvailable N/A ✔️ number NUMBER 0 The asset amount that is available in the vault.
LossUnrealized N/A ✔️ number NUMBER 0 The potential loss amount that is not yet realized expressed as the vaults asset.
AssetMaximum Yes number NUMBER 0 The maximum asset amount that can be held in the vault. Zero value 0 indicates there is no cap.
MPTokenIssuanceID N/A ✔️ number UINT192 0 The identifier of the share MPTokenIssuance object.
WithdrawalPolicy No ✔️ string UINT8 N/A Indicates the withdrawal strategy used by the Vault.
2.1.2.1 Flags

The Vault object supports the following flags:

Flag Name Flag Value Modifiable? Description
lsfVaultPrivate 0x0001 No If set, indicates that the vault is private.

2.1.3 Vault _pseudo-account_

An AccountRoot entry holds the XRP, IOU or MPT deposited into the vault. It also acts as the issuer of the vault's shares. The pseudo-account follows the XLS-64d specification for pseudo accounts. The AccountRoot object is created when creating the Vault object.

2.1.4 Ownership

The Vault objects are stored in the ledger and tracked in an Owner Directory owned by the account submitting the VaultSet transaction. Furthermore, to facilitate Vault object lookup from the vault shares, the object is also tracked in the OwnerDirectory of the pseudo-account.

2.1.5 Owner Reserve

The Vault object costs one reserve fee per object created:

  • The Vault object itself.
  • The MPTokenIssuance associated with the shares of the Vault.

2.1.6 Vault Shares

Shares represent the portion of the Vault assets a depositor owns. Vault Owners set the currency code of the share and whether the token is transferable during the vault's creation. These two values are immutable. The share is represented by a Multi-Purpose Token. The MPT is issued by the vault's pseudo-account.

2.1.6.1 MPTokenIssuance

The MPTokenIssuance object represents the share on the ledger. It is created and deleted together with the Vault object.

2.1.6.1.1 MPTokenIssuance Values

Here’s the table with the headings "Field," "Description," and "Value":

Field Description Value
Issuer The AccountID of the Vault's pseudo-account. pseudo-account ID
MaximumAmount No limit to the number of shares that can be issued. 0xFFFFFFFFFFFFFFFF
TransferFee The fee paid to transfer the shares. 0
MPTokenMetadata Arbitrary metadata about the share MPT, in hex format. -

Flags

The following flags are set based on whether the shares are transferable and if the vault is public or private.

Condition Transferable Non-Transferable
Public Vault lsfMPTCanEscrow
lsfMPTCanTrade
lsfMPTCanTransfer		 No Flags
Private Vault lsfMPTCanEscrow
lsfMPTCanTrade
lsfMPTCanTransfer
lsfMPTRequireAuth		 lsfMPTRequireAuth
2.1.6.2 MPToken

The MPToken object represents the amount of shares held by a depositor. It is created when the account deposits liquidity into the vault and is deleted when a depositor redeems (or transfers) all shares.

2.1.6.2.1 MPToken Values

The MPToken values should be set as per the MPT specification.

Condition Transferable Non-Transferable
Public Vault No Flags lsfMPTAuthorized
Private Vault lsfMPTAuthorized lsfMPTAuthorized

2.1.7 Exchange Algorithm

Exchange Algorithm refers to the logic that is used to exchange assets into shares and shares into assets. This logic is executed when depositing or redeeming liquidity. A Vault comes with the default exchange algorithm, which is detailed below.

2.1.7.1 Unrealized Loss

A well-informed depositor may learn of an incoming loss and redeem their shares early, causing the remaining depositors to bear the full loss. To discourage such behaviour, we introduce a concept of "paper loss," captured by the Vault object's LossUnrealized attribute. The "paper loss" captures a potential loss the vault may experience and thus temporarily decreases the vault value. Only a protocol connected to the Vault may increase or decrease the LossUnrealized attribute.

The "paper loss" temporarily decreases the vault value. A malicious depositor may take advantage of this to deposit assets at a lowered price and withdraw them once the price increases.

Consider a vault with a total value of $1.0m and total shares of $1.0m. Assume the "paper loss" for the vault is $900k. The new exchange rate is as follows:

$$ exchangeRate = \frac{AssetTotal - LossUnrealized}{ShareTotal} $$

$$ exchangeRate = \frac{1,000,000 - 900,000}{1,000,000} = 0.1 $$

After the "paper loss" is cleared, the new effective exchange rate would be as follows:

$$ exchangeRate = \frac{AssetTotal}{ShareTotal} $$

$$ exchangeRate = \frac{1,000,000}{1,000,000} = 1.0 $$

A depositor could deposit $100k assets at a 0.1 exchange rate and get 1.0m shares. Once the "paper loss" is cleared, their shares would be worth $1.0m.

To account for this problem, the Vault must use two different exchange rate models: one for depositing assets and one for withdrawing them.

2.1.7.2 Exchange Rate Algorithms

Variables

The following variables define the Vault balance:

  • $\Gamma_{share}$ - the total number of shares issued by the vault.

  • $\Gamma_{asset}$ - the total assets in the vault, including any future yield.

  • $\Delta_{asset}$ - the change in the total amount of assets after a deposit, withdrawal, or redemption.

  • $\Delta_{share}$ - che change in the total amount of shares after a deposit, withdrawal, or redemption.

  • $\iota$ - the unrealized loss of the vault.

2.1.7.2.1 Deposit

We compute the number of shares ($\Delta_{share}$) a depositor will receive as follows:

$$\Delta_{share} = \Delta_{asset} \times \frac{\Gamma_{share}}{\Gamma_{asset} + 0^{\Gamma_{asset}}} $$

The following equations govern the updated vault composition after a successful deposit:

  • $\Gamma_{asset} = \Gamma_{asset} + \Delta_{asset}$ New balance of assets in the vault.
  • $\Gamma_{share} = \Gamma_{share} + \Delta_{share}$ New share balance in the vault.
2.1.7.2.2 Redeem

We compute the number of assets ($\Delta_{asset}$) returned by burning $\Delta_{share}$ as follows:

$$\Delta_{asset} = \Delta_{share} \times \frac{\Gamma_{asset} - \iota}{\Gamma_{share} + 0^{\Gamma_{share}}} $$

The following equations govern the updated vault composition after a successful redemption:

  • $\Gamma_{asset} = \Gamma_{asset} - \Delta_{asset}$ New balance of assets in the vault.
  • $\Gamma_{share} = \Gamma_{share} - \Delta_{share}$ New share balance in the vault.
2.1.7.2.3 Withdraw

We compute the number of shares to burn to withdraw $\Delta_{asset}$ as follows:

$$\Delta_{share} = \Delta_{asset} \times \frac{\Gamma_{share}}{\Gamma_{asset} - \iota + 0^{\Gamma_{asset}}} $$

The following equations govern the updated vault composition after a successful withdrawal:

  • $\Gamma_{asset} = \Gamma_{asset} - \Delta_{asset}$ New balance of assets in the vault.
  • $\Gamma_{share} = \Gamma_{share} - \Delta_{share}$ New share balance in the vault.
2.1.7.3 Withdrawal Policy

Withdrawal policy controls the logic used when removing liquidity from a vault. Each strategy has its own implementation, but it can be used in multiple vaults once implemented. Therefore, different vaults may have different withdrawal policies. The specification introduces the following options:

2.1.7.3.1 first-come-first-serve

The First Come, First Serve strategy treats all requests equally, allowing a depositor to redeem any amount of assets provided they have a sufficient number of shares.

2.1.8 Frozen Assets

The issuer of the Vaults asset may enact a freeze either through a Global Freeze for IOUs or locking MPT. When the vaults asset is frozen, it can only be withdrawn by specifying the Destination account as the Issuer of the asset. Similarly, a frozen asset may not be deposited into a vault. Furthermore, when the asset of a vault is frozen, the shares corresponding to the asset may not be transferred.

2.1.9 Transfer Fees

The Vault does not apply the Transfer Fee to VaultDeposit and VaultWithdraw transactions. Furthermore, whenever a protocol moves assets from or to a Vault, the Transfer Fee must not be charged.

Return to Index

3. Transactions

All transactions introduced by this proposal incorporate the common transaction fields that are shared by all transactions. Standard fields are only documented in this proposal if needed because this proposal introduces new possible values for such fields.

3.1 VaultCreate, VaultSet, VaultDelete transactions

The Vault object is managed with VaultCreate, VaultSet and VaultDelete transactions.

3.1.1 VaultCreate Transaction

The VaultCreate transaction creates a new Vault object.

Field Name Required? JSON Type Internal Type Default Value Description
TransactionType ✔️ string Uint16 58 The transaction type.
Flags ✔️ number Uint32 0 Specifies the flags for the Vault.
Data string Blob Arbitrary Vault metadata, limited to 256 bytes.
Asset ✔️ string or object Issue N/A The asset (XRP, IOU or MPT) of the Vault.
AssetMaximum number Uint64 0 The maximum asset amount that can be held in a vault.
MPTokenMetadata string Blob Arbitrary metadata about the share MPT, in hex format, limited to 1024 bytes.
WithdrawalPolicy number UINT8 strFirstComeFirstServe Indicates the withdrawal strategy used by the Vault.
DomainID string Hash256 The PermissionedDomain object ID associated with the shares of this Vault.
3.1.1.1 Flags
Flag Name Flag Value Description
tfVaultPrivate 0x0001 Indicates that the vault is private. It can only be set during Vault creation.
tfVaultShareNonTransferable 0x0002 Indicates the vault share is non-transferable. It can only be set during Vault creation.
3.1.1.2 WithdrawalPolicy

The type indicates the withdrawal strategy supported by the vault. The following values are supported:

Strategy Name Value Description
strFirstComeFirstServe 0x0001 Requests are processed on a first-come-first-serve basis.
3.1.1.3 Transaction Fees

The transaction creates an AccountRoot object for the _pseudo-account_. Therefore, the transaction must destroy one incremental owner reserve amount.

3.1.1.4 Failure Conditions

  • The Asset is MPT:

    • The lsfMPTCanTransfer is not set in the MPTokenIssuance object. (the asset is not transferable).
    • The lsfMPTLocked flag is set in the MPTokenIssuance object. (the asset is locked).

  • The Asset is an IOU:

    • The lsfGlobalFreeze flag is set on the issuing account (the asset is frozen).

  • The tfVaultPrivate flag is not set and the DomainID is provided. (The VaultOwner is attempting to create a public Vault with a PermissionedDomain)

  • The PermissionedDomain object does not exist with the provided DomainID.

  • The Data field is larger than 256 bytes.

  • The account submiting the transaction has insufficient AccountRoot.Balance for the Owner Reserve.

3.1.1.5 State Changes

  • Create a new Vault ledger object.

  • Create a new MPTokenIssuance ledger object for the vault shares.

    • If the DomainID is provided:
      • MPTokenIssuance(Vault.MPTokenIssuanceID).DomainID = DomainID (Set the Permissioned Domain ID).

  • Create a new AccountRootpseudo-account object setting the PseudoOwner to VaultID.

  • If Vault.Asset is an IOU:

    • Create a RippleState object between the pseudo-account AccountRoot and Issuer AccountRoot.

  • If Vault.Asset is an MPT:

    • Create MPToken object for the pseudo-account for the Asset.MPTokenIssuance.
3.1.1.6 Invariants

TBD

Return to Index

3.1.2 VaultSet Transaction

The VaultSet updates an existing Vault ledger object.

Field Name Required? JSON Type Internal Type Default Value Description
TransactionType ✔️ string Uint16 59 The transaction type.
VaultID ✔️ string Hash256 N/A The ID of the Vault to be modified. Must be included when updating the Vault.
Data string Blob Arbitrary Vault metadata, limited to 256 bytes.
AssetMaximum number Uint64 The maximum asset amount that can be held in a vault. The value cannot be lower than the current AssetTotal unless the value is 0.
DomainID string Hash256 The PermissionedDomain object ID associated with the shares of this Vault.
3.1.2.1 Failure Conditions
  • Vault object with the specified VaultID does not exist on the ledger.
  • The submitting account is not the Owner of the vault.
  • The Data field is larger than 256 bytes.
  • If Vault.AssetMaximum > 0 AND AssetMaximum > 0 AND:
    • The AssetMaximum < Vault.AssetTotal (new AssetMaximum cannot be lower than the current AssetTotal).
  • The sfVaultPrivate flag is not set and the DomainID is provided (Vault Owner is attempting to set a PermissionedDomain to a public Vault).
  • The PermissionedDomain object does not exist with the provided DomainID.
  • The transaction is attempting to modify an immutable field.
  • The transaction does not specify any of the modifiable fields.
3.1.2.2 State Changes
  • Update mutable fields in the Vault ledger object.
  • If DomainID is provided:
    • Set MPTokenIssuance(Vault.MPTokenIssuanceID).DomainID = DomainID (Set the Permissioned Domain).
3.1.2.3 Invariants

TBD

Return to Index

3.1.3 VaultDelete Transaction

The VaultDelete transaction deletes an existing vault object.

Field Name Required? JSON Type Internal Type Default Value Description
TransactionType ✔️ string Uint16 60 Transaction type.
VaultID ✔️ string Hash256 N/A The ID of the vault to be deleted.
3.1.3.1 Failure Conditions
  • Vault object with the VaultID does not exist on the ledger.
  • The submitting account is not the Owner of the vault.
  • AssetTotal, AssetAvailable, or MPTokenIssuance(Vault.MPTokenIssuanceID).OutstandingAmount are greater than zero.
  • The OwnerDirectory of the Vault pseudo-account contains pointers to objects other than the Vault, the MPTokenIssuance for its shares, or an MPToken or trust line for its asset.
3.1.3.2 State Changes
  • Delete the MPTokenIssuance object for the vault shares.
  • Delete the MPToken or RippleState object corresponding to the vault's holding of the asset, if one exists.
  • Delete the AccountRoot object of the pseudo-account, and its DirectoryNode objects.
  • Release the Owner Reserve to the Vault.Owner account.
  • Delete the Vault object.
3.1.3.3 Invariants

TBD

Return to Index

3.2 VaultDeposit and VaultWithdraw transactions

Depositors call the VaultDeposit and VaultWithdraw transactions to add or remove assets from the Tokenized Vault.

Return to Index

3.2.1 VaultDeposit transaction

The VaultDeposit transaction adds Liqudity in exchange for vault shares.

Field Name Required? JSON Type Internal Type Default Value Description
TransactionType ✔️ string UINT16 61 Transaction type.
VaultID ✔️ string HASH256 N/A The ID of the vault to which the assets are deposited.
Amount ✔️ string or object AMOUNT N/A Asset amount to deposit.
3.2.1.1 Failure conditions

  • Vault object with the VaultID does not exist on the ledger.

  • The asset type of the vault does not match the asset type the depositor is depositing.

  • The depositor does not have sufficient funds to make a deposit.

  • Adding the Amount to the AssetTotal of the vault would exceed the AssetMaximum.

  • The Vault lsfVaultPrivate flag is set and the Account depositing the assets does not have credentials in the permissioned domain of the share.

  • The Vault.Asset is MPT:

    • MPTokenIssuance.lsfMPTCanTransfer is not set (the asset is not transferable).
    • MPTokenIssuance.lsfMPTLocked flag is set (the asset is globally locked).
    • MPToken(MPTokenIssuanceID, AccountID).lsfMPTLocked flag is set (the asset is locked for the depositor).
    • MPToken(MPTokenIssuanceID, AccountID).MPTAmount < Amount (insufficient balance).

  • The Asset is an IOU:

    • The lsfGlobalFreeze flag is set on the issuing account (the asset is frozen).
    • The lsfHighFreeze or lsfLowFreeze flag is set on the RippleState object between the Asset Issuer and the depositor.
    • The RippleState object Balance < Amount (insufficient balance).
3.2.1.2 State Changes

If no MPToken object exists for the depositor, create one. For object details, see 3.4.2 MPToken.

  • Increase the MPTAmount field of the share MPToken object of the Account by $\Delta_{share}$.

  • Increase the OutstandingAmount field of the share MPTokenIssuance object by $\Delta_{share}$.

  • Increase the AssetTotal and AssetAvailable of the Vault by Amount.

  • If the Vault.Asset is XRP:

    • Increase the Balance field of pseudo-account AccountRoot by Amount.
    • Decrease the Balance field of the depositor AccountRoot by Amount.

  • If the Vault.Asset is an IOU:

    • Increase the RippleState balance between the pseudo-account AccountRoot and the Issuer AccountRoot by Amount.
    • Decrease the RippleState balance between the depositor AccountRoot and the Issuer AccountRoot by Amount.

  • If the Vault.Asset is an MPT:

    • Increase the MPToken.MPTAmount by Amount of the pseudo-account MPToken object for the Vault.Asset.
    • Decrease the MPToken.MPTAmount by Amount of the depositor MPToken object for the Vault.Asset.
3.2.1.3 Invariants

TBD

Return to Index

3.2.2 VaultWithdraw transaction

The VaultWithdraw transaction withdraws assets in exchange for the vault's shares.

Field Name Required? JSON Type Internal Type Default Value Description
TransactionType ✔️ string UINT16 62 Transaction type.
VaultID ✔️ string HASH256 N/A The ID of the vault from which assets are withdrawn.
Amount ✔️ number STAmount 0 The exact amount of Vault asset to withdraw.
Destination string AccountID Empty An account to receive the assets. It must be able to receive the asset.

If Amount is the Vaults asset, calculate the share cost using the Withdraw formula. If Amount is the Vaults share, calculate the assets amount using the Redeem formula.

In sections below assume the following variables:

  • $\Gamma_{share}$ - the total number of shares issued by the vault.

  • $\Gamma_{asset}$ - the total assets in the vault, including any future yield.

  • $\Delta_{asset}$ - the change in the total amount of assets after a deposit, withdrawal, or redemption.

  • $\Delta_{share}$ - che change in the total amount of shares after a deposit, withdrawal, or redemption.

3.2.2.1 Failure conditions

  • Vault object with the VaultID does not exist on the ledger.

  • The Vault.Asset is MPT:

    • MPTokenIssuance.lsfMPTCanTransfer is not set (the asset is not transferable).
    • MPTokenIssuance.lsfMPTLocked flag is set (the asset is globally locked).
    • MPToken(MPTokenIssuanceID, AccountID | Destination).lsfMPTLocked flag is set (the asset is locked for the depositor or the destination).

  • The Asset is an IOU:

    • The lsfGlobalFreeze flag is set on the issuing account (the asset is frozen).
    • The lsfHighFreeze or lsfLowFreeze flag is set on the RippleState object between the Asset Issuer and the AccountRoot of the AccountID or the Destination.

  • The unit of Amount is not shares of the vault.

  • The unit of Amount is not asset of the vault.

  • There is insufficient liquidity in the vault to fill the request:

    • If Amount is the vaults share:

      • MPTokenIssuance(Vault.MPTokenIssuanceID).OutstandingAmount < Amount (attempt to withdraw more shares than there are in total).
      • The shares MPToken.MPTAmount of the Account is less than Amount (attempt to withdraw more shares than owned).
      • Vault.AssetAvailable < $\Delta_{asset}$ (the vault has insufficient assets).

    • If Amount is the vaults asset:

      • The shares MPToken.MPTAmount of the Account is less than $\Delta_{share}$ (attempt to withdraw more shares than owned).
      • Vault.AssetAvailable < Amount (the vault has insufficient assets).

  • The Destination account is specified and it does not have permission to receive the asset.

3.2.2.2 State Changes

  • If the Vault.Asset is XRP:

    • Decrease the Balance field of pseudo-account AccountRoot by $\Delta_{asset}$.
    • Increase the Balance field of the depositor AccountRoot by $\Delta_{asset}$.

  • If the Vault.Asset is an IOU:

    • If the Depositor (or Destination) account does not have a RippleState object for the Vaults Asset, create the RippleState object.

    • Decrease the RippleState balance between the pseudo-account AccountRoot and the Issuer AccountRoot by $\Delta_{asset}$.

    • Increase the RippleState balance between the depositor AccountRoot and the Issuer AccountRoot by $\Delta_{asset}$.

  • If the Vault.Asset is an MPT:

    • If the Depositor (or Destination) account does not have a MPToken object for the Vaults Asset, create the MPToken object.

    • Decrease the MPToken.MPTAmount by $\Delta_{asset}$ of the pseudo-account MPToken object for the Vault.Asset.

    • Increase the MPToken.MPTAmount by $\Delta_{asset}$ of the depositor MPToken object for the Vault.Asset.

  • Update the MPToken object for the Vault.MPTokenIssuanceID of the depositor AccountRoot:

    • Decrease the MPToken.MPTAmount by $\Delta_{share}$.
    • If MPToken.MPTAmount == 0, delete the object.

  • Update the MPTokenIssuance object for the Vault.MPTokenIssuanceID:

    • Decrease the OutstandingAmount field of the share MPTokenIssuance object by $\Delta_{share}$.

  • Decrease the AssetTotal and AssetAvailable by $\Delta_{asset}$

3.2.2.3 Invariants

TBD

Return to Index

3.3 VaultClawback Transaction

3.3.1 VaultClawback transaction

The VaultClawback transaction performs a Clawback from the Vault, exchanging the shares of an account. Conceptually, the transaction performs VaultWithdraw on behalf of the Holder, sending the funds to the Issuer account of the asset. In case there are insufficient funds for the entire Amount the transaction will perform a partial Clawback, up to the Vault.AssetAvailable. The Clawback transaction must respect any future fees or penalties.

Field Name Required? JSON Type Internal Type Default Value Description
TransactionType ✔️ string UINT16 63 Transaction type.
VaultID ✔️ string HASH256 N/A The ID of the vault from which assets are withdrawn.
Holder ✔️ string AccountID N/A The account ID from which to clawback the assets.
Amount number NUMBER 0 The asset amount to clawback. When Amount is 0 clawback all funds, up to the total shares the Holder owns.
3.3.1.1 Failure conditions

  • Vault object with the VaultID does not exist on the ledger.

  • If Vault.Asset is XRP.

  • If Vault.Asset is an IOU and:

    • The Issuer account is not the submitter of the transaction.

  • If Vault.Asset is an MPT and:

    • MPTokenIssuance.Issuer is not the submitter of the transaction.

  • The MPToken object for the Vault.MPTokenIssuanceID of the Holder AccountRoot does not exist OR MPToken.MPTAmount == 0.

3.3.1.2 State Changes

  • If the Vault.Asset is an IOU:

    • Decrease the RippleState balance between the pseudo-account AccountRoot and the Issuer AccountRoot by min(Vault.AssetAvailable, $\Delta_{asset}$).

  • If the Vault.Asset is an MPT:

    • Decrease the MPToken.MPTAmount by min(Vault.AssetAvailable, $\Delta_{asset}$) of the pseudo-account MPToken object for the Vault.Asset.

  • Update the MPToken object for the Vault.MPTokenIssuanceID of the depositor AccountRoot:

    • Decrease the MPToken.MPTAmount by $\Delta_{share}$.
    • If MPToken.MPTAmount == 0, delete the object.

  • Update the MPTokenIssuance object for the Vault.MPTokenIssuanceID:

    • Decrease the OutstandingAmount field of the share MPTokenIssuance object by $\Delta_{share}$.

  • Decrease the AssetTotal and AssetAvailable by min(Vault.AssetAvailable, $\Delta_{asset}$)

3.3.1.3 Invariants

TBD

Return to Index

3.4 Payment Transaction

3.4.1 Payment transaction

The Single Asset Vault does not introduce new Payment transaction fields. However, it adds additional failure conditions and state changes when transfering Vault shares.

3.4.1.1 Failure Conditions

  • If Payment.Amount is a Vault share AND:

    • The Vault lsfVaultPrivate flag is set and the Payment.Destination account does not have credentials in the permissioned domain of the Vaults Share.

    • The Vault tfVaultShareNonTransferable flag is set.

    • The Vault.Asset is MPT:

      • MPTokenIssuance.lsfMPTCanTransfer is not set (the asset is not transferable).
      • MPTokenIssuance.lsfMPTLocked flag is set (the asset is globally locked).
      • MPToken(MPTokenIssuanceID, AccountID).lsfMPTLocked flag is set (the asset is locked for the payer).
      • MPToken(MPTokenIssuanceID, PseudoAccountID).lsfMPTLocked flag is set (the asset is locked for the pseudo-account).
      • MPToken(MPTokenIssuanceID, Destination).lsfMPTLocked flag is set (the asset is locked for the destination account).

    • The Vault.Asset is an IOU:

      • The lsfGlobalFreeze flag is set on the issuing account (the asset is frozen).
      • The lsfHighFreeze or lsfLowFreeze flag is set on the RippleState object between the Asset Issuer and the payer account.
      • The lsfHighFreeze or lsfLowFreeze flag is set on the RippleState object between the Asset Issuer and the destination account.
      • The lsfHighFreeze or lsfLowFreeze flag is set on the RippleState object between the Asset Issuer and the pseudo-account.

3.4.1.2 State Changes

  • If MPTokenobject for shares does not exist for the destination account, create one.

Return to Index

4. API

4.1 RPC ledger_entry

This method retrieves ledger object. In particular, it retrieves a Vault object by its ID. The specification purposefully ommits general fields. These can be found here.

4.1.1 Request Fields

We propose adding the following fields to the ledger_entry method:

Field Name Required? JSON Type Description
vault_id ✔️ string The object ID of the Vault to be returned.

4.1.2 Response

Field Name Required? JSON Type Description
LedgerEntryType ✔️ string Ledger object type.
LedgerIndex ✔️ string Ledger object identifier.
Flags ✔️ string Ledger object flags.
PreviousTxnID ✔️ string Identifies the transaction ID that most recently modified this object.
PreviousTxnLgrSeq ✔️ number The sequence of the ledger that contains the transaction that most recently modified this object.
Sequence ✔️ number The transaction sequence number that created the vault.
OwnerNode ✔️ number Identifies the page where this item is referenced in the owner's directory.
Owner ✔️ string The account address of the Vault Owner.
Account ✔️ string The address of the Vaults pseudo-account.
Data ✔️ string Arbitrary metadata about the Vault. Limited to 256 bytes.
Asset ✔️ string or object The asset of the vault. The vault supports XRP, IOU and MPT.
AssetTotal ✔️ number The total value of the vault.
AssetAvailable ✔️ number The asset amount that is available in the vault.
LossUnrealized ✔️ number The potential loss amount that is not yet realized expressed as the vaults asset.
AssetMaximum ✔️ number The maximum asset amount that can be held in the vault. Zero value 0 indicates there is no cap.
Share ✔️ object The MPT object of the vault share.
WithdrawalPolicy ✔️ string Indicates the withdrawal strategy used by the Vault.

4.1.2.1 Example

{
  "LedgerEntryType": "Vault",
  "LedgerIndex": "E123F4567890ABCDE123F4567890ABCDEF1234567890ABCDEF1234567890ABCD",
  "Flags": "0",
  "PreviousTxnID": "9A8765B4321CDE987654321CDE987654321CDE987654321CDE987654321CDE98",
  "PreviousTxnLgrSeq": 12345678,
  "Sequence": 1,
  "OwnerNode": 2,
  "Owner": "rEXAMPLE9AbCdEfGhIjKlMnOpQrStUvWxYz",
  "Account": "rPseudoAcc1234567890abcdef1234567890abcdef",
  "Data": "5468697320697320617262697472617279206D657461646174612061626F757420746865207661756C742E",
  "Asset": {
    "currency": "USD",
    "issuer": "rIssuer1234567890abcdef1234567890abcdef",
    "value": "1000"
  },
  "AssetTotal": 1000000,
  "AssetAvailable": 800000,
  "LossUnrealized": 200000,
  "AssetMaximum": 0,
  "Share": {
    "mpt_issuance_id": "0000012FFD9EE5DA93AC614B4DB94D7E0FCE415CA51BED47",
    "value": "1", 
  },
  "ShareTotal": 5000,
  "WithdrawalPolicy": "0x0001"
}

Return to Index

Appendix

Return to Index

A-1 F.A.Q.

A-1.1 Why does the specification allow both Withdraw and Redeem and not just one of them?

We chose this design in order to reduce the amount of off-chain math required to be implemented by XRPL users and/or developers

A-1.2 Why can any account that holds Vaults shares submit a VaultWithdraw transaction?

The VaultWithdraw transaction does not respect the permissioned domain rules. In other words, any account that holds the shares of the Vault can withdraw them.

The decision was made to avoid a situation where a depositor deposits assets to a private vault to then have their access revoked by invalidating their credentials, and thus loosing access to their funds.

A-1.3 How can a depositor transfer shares to another account?

Vault shares are a first-class assets, meaning that they can be transfered and used in other on-ledger protocols that support MPTokens. However, the payee (or the receiver) of the shares must have permissions to hold the shares and the assset that the shares represent. For example, if the shares are for a private Vault containing USDC the destination account must be in the permissioned domain of the Vault, and have permissions to hold USDC.

In addion, any compliance mechanisms applied to USDC will also apply to the share. For example, if the Issuer of USDC freezes the Trustline of the payee, then the payee will not be able to receive any shares representing USDC.

A-1.4 What is the difference between the VaultOwner and the pseudo-account?

XRP Ledger is an account based blockchain. That means that assets (XRP, IOU and MPT must be held by an account). The Vault Object (or any other object, such as the AMM) cannot hold assets directly. Therefore, a pseudo-account is created that holds the assets on behalf of that object. The pseudo-account is a stand-alone account, that cannot receive funds, it cannot send transactions, it is there to only hold assets. So for example, when a depositor deposits assets into a vault, in reality this transaction moves the assets from the depositor account to the pseudo-account.