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Trustline Credit Network

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Trustline is creating the first trustless, crypto-backed stablecoin issued on the XRP Ledger and the Flare Network via the power of Flare Network smart contracts. This trustless stablecoin is entitled Aurei (AUR). Aurei is the advent of an idea from the Flare Network blog series authored by Hugo Philion. Trustline is seeking to build a crypto credit network for use on the XRPL and Flare Network. Through the Probity treasury and vaults, users will be able to provide collateral and earn interest for the minting of AUR to be lent out to borrowers. All of this is accomplished through smart contracts and the use of an adjustable interest rate that derives itself from the balance between supply and demand. With the utilization of trustlines and issued currency features, Trustline is an enabling the creation of the first decentralized, trustless, stable unit of account on the XRPL.

Trustline will also feature a P2P payments function on the mobile application allowing users to pay each other like popular fiat payment apps like PayPal, Venmo, and CashApp. Merchants will be able to plug into the ecosystem and except payment via AUR or possibly other payment methods in the future. This would allow merchants to avoid costly credit processing fees. Additional features are still being worked out like the way to provide a decentralized credit score so borrowers will not always have to post collateral to receive a loan, which could allow institutions to lend at scale. 


Probity is structured as a decentralized banking application allowing the lending, borrowing, and trading of the Aurei stablecoin by accessing Trustline Credit Network smart contracts. The three main functions of Probity are the teller, treasury, and vault smart contracts that facilitate the participation in the Trustline Credit Network. The teller function tracks the outstanding debt balances and creates the loans for borrowers throughout the network. The treasury smart contract locks collateral for the issuance of AUR and keeps record of reserves which is the amount of liquid AUR for lending. The vault smart contract allows the user to manage, store, deposit, and withdrawal collateral denominated in Spark (FLR), f-assets, or other ERC20 compliant tokens. These three smart contract functions are the bedrock of the Trustline Credit Network.

Aurei Stablecoin

The Aurei (AUR) stablecoin is pegged to the US Dollar (USD) and issued on the XRPL and Flare Network allowing it to transact for fractions of a penny and within seconds. Additionally, AUR through the power of trustlines and issued currencies can be traded on the XRPL DEX providing it with a much needed stable unit of account for XRP and other ICs to trade off of. The interest rate for the borrowing and lending of AUR is flexible due to its derivation from the equilibrium between supply and demand. This means market forces will determine the most appropriate rate for borrowing and lending through the interest rate formula, which is as follows:

R(t) = 1 / 100 * (1 – U(t))

In this formula, R(t) represents the interest rate at a given time. The utilization ratio defined as U(t) is representative of the the AUR liquid reserves over the the total AUR supply. For example, if there was 50 AUR liquid reserves with 100 AUR in total supply, then the utilization ratio would be 0.5. In this scenario, the interest rate would be equal to 2% APY. However, the interest rate will increase over time if the demand increases relative to supply and vice versa. AUR as a trustless stablecoin on the XRPL and Flare Network will bring immense value to the payments and DeFi spaces.

TCN Governance Token

The Trustline Credit Network (TCN) token can be earned via interest for providing collateral and through trading. Its main function is to serve as the governance token for the Trustline ecosystem, which may put a slight premium on its price resulting in it being a semi-stablecoin. TCN and AUR are the two choices for suppliers of the Probity vault contract to earn their interest in; however, suppliers may prefer to receive interest in the form of TCN due to the premium that could be place on its ownership for governance. The voting power that comes with TCN allows stakeholders to vote on network upgrades, parameter changes, and collateral types. 

Aurei Minting Process

1 FXRP = $1 USD; 1.5x collateral ratio

Aurei Minting Process
  • Mickey deposits 1500 FXRP to the Probity vault to be used as collateral for the minting of Aurei (AUR). Each user has their own vault as this is just a smart contract to allow users to manage their collateral through.
  • Mickey calls on the treasury smart contract to mint 1000 AUR (1500 FXRP / 1.5 collateral ratio). The vault locks Mickey’s FXRP collateral in the vault, while the treasury mints the new AUR and stores it as part of the AUR reserves.
  • The teller smart contract then receives a bid for 500 AUR to be loaned out. 500 AUR is removed from the treasury reserves resulting in a utilization ratio of 50% as 500 AUR out of 1000 AUR total supply is now loaned out. Mickey receives interest for allowing the AUR he minted to be loaned out. Trustline features an adjustable interest rate governed by the market forces of supply and demand. In this instance, Mickey receives 2% APY (1 / 100 * (1 – 0.5)) for the 500 AUR that has been loaned out.
  • It is important to note that Lars, the borrower in this scenario, will also be required to post collateral to insure the payment of accrued interest. If Lars were to fail to make a payment than the power of smart contracts will take the interest payable from Lars’s locked collateral.
  • As the utilization ratio changes, the interest Mickey receives will increase as demand increases and decrease as supply increases relative to one another. Mickey also has the option to receive interest paid out in AUR or TCN. If all of this stayed the same over the course of one year, Mickey would receive either 10 AUR or 10 TCN in interest payable to him during that time for the 500 AUR that is borrowed by Lars.