Flare Smart Accounts

The Flare Smart Accounts is an account abstraction that allows XRPL users to perform actions on the Flare chain without owning any FLR token. Each XRPL address is assigned a unique smart account on the Flare chain, which only it can control. They do so through Payment transactions on the XRPL. The Flare Smart Accounts are especially useful as a way of interacting with the FAssets workflow.

Workflow

The workflow for Flare Smart Accounts is comprised of the following steps.

1. The XRPL user sends instructions as a Payment transaction to a specific XRPL address, with instructions encoded as the payment reference in the memo field.
2. The operator interacts with the Flare Data Connector to procure a Payment proof. It then calls the executeTransaction function on the MasterAccountController contract, with the Payment proof and the XRPL address that made the transaction.
3. The XRPL user's smart account performs the actions given in the instructions.

1. Instructions on XRPL

The Flare Smart Accounts allow XRPL users to perform actions on the Flare chain through instructions on the XRPL. This is done through a Payment to an XRPL address, designated by the operator - a backend monitoring incoming transactions and interacting with the Flare chain. The payment must transfer sufficient funds, as specified by the operator, and must include the proper payment receipt in the memo field.

The payment receipt is a bytes32 value. The first byte is reserved for the instruction code, a byte representation of a two-digit number. The remaining 31 bytes are the parameters for the chosen instruction.

In practice, the payment receipt should be prepared by a backend, through a web form.

Table of instruction IDs and corresponding actions.

Instruction ID	Action	Description
01	deposit	Deposit an amount of FXRP into the Firelight vault, designated by the MasterAccountController contract.
02	withdraw	Withdraw an amount of FXRP from the Firelight vault, designated by the MasterAccountController contract.
03	approve	Deprecated. Approve the Firelight vault, designated by the MasterAccountController contract, to spend an amount of FXRP from your account.
04	redeem	Redeem lots of FXRP. The redemption will be handled by the executor, specified by the MasterAccountController contract.
05	reserveCollateral	Reserve lots of collateral in the agentVault, specified by the MasterAccountController contract. The collateral reservation will be handled by the executor, also specified by the MasterAccountController contract.
06	claimWithdraw	Claim the withdrawal from the Firelight vault.
99	custom	Execute a list of custom function calls. The custom instructions need to be registered in advance, with the MasterAccountController (registerCustomInstruction function).

 

2. Payment proof on Flare

The operator monitors incoming transactions to the specified XRPL address. Upon receiving a payment, it makes a Payment attestation request to the FDC. The Payment proof and the user's XRPL address are passed to the executeTransaction function on the MasterAccountController smart contract on the Flare chain.

The MasterAccountController contract first verifies the proof. It then performs several checks on the proof:

• receiving address matches the one specified by the operator,
• the source address matches the XRPL address given to the function,
• that the proof has not yet been used for the same actions.

Then, the MasterAccountController contract retrieves the XRPL user's smart account from a mapping. If the account does not yet exist, it is created at this point.

The payment reference is decoded. Depending on the value of the leading byte, a different function on the smart account is called.

3. Actions on Flare

The XRPL user's smart account performs the actions in the instructions.