Synchronicity Price Adapters

The repository contains the Price Adapter contracts for the assets, in which prices are correlated with different token rather than the pool's base one.

For example, the Aave v2 pool on Ethereum uses ETH-based oracles to calculate the collateral value, debt value and health factor of a user. This, coupled with the delay at which different price feeds update, introduces unnecessary volatility in positions that involve stablecoins used both as collateral and as debt. Replacement of the current ETH-based oracles for stablecoins by using USD pairs instead will normalize the USD price using the ETH oracle and will reduce the volatility between stablecoins as all the stablecoin price feeds will update atomically when the ETH price changes.

The same approach could be used for ETH-correlated assets on USD-based pools, for example, stETH / ETH and ETH / USD feeds could be used to calculate the stETH price.

This repository also contains the proposal smart contracts for using price adapters for stablecoins on the Aave v2 Ethereum and Aave Arc pool.

AaveOracle

Affected smart contract is AaveOracle, where currently all asset sources are set to Chainlink Data Feeds for pairs $Asset / ETH$.

Proposal is to deploy CLSynchronicityPriceAdapterBaseToPeg for all stablecoin assets, which will calculate the price of Asset / ETH by querying Chainlink Data Feeds for pairs Asset / USD and ETH / USD, using the formula: $$Price(Asset / ETH) = {DataFeed(Asset / USD) \over DataFeed(ETH / USD)}$$

Proposal is to change asset source for all stablecoin assets to be CLSynchronicityPriceAdapter which calculates price by querying Chainlink Data Feeds for pairs Asset / USD and ETH / USD.

Implementation

Price Adapter

CLSynchronicityPriceAdapterBaseToPeg

• Price adapter smart contract where ChainlinkAggregator addresses for Asset / USD and ETH / USD are set.
• Feeds must have the same decimals value.
• Using this two feeds, it calculates the price for pair Asset / ETH.
• Returning price is calculated with 18 decimals.

CLSynchronicityPriceAdapterPegToBase

• Price adapter smart contract where ChainlinkAggregator addresses for Asset / ETH and ETH / USD are set.
• Using this two feeds, it calculates the price for pair Asset / USD.
• Returning price is calculated with 18 decimals.

CLwstETHSynchronicityPriceAdapter

• Price adapter smart contract which calculates wstETH / USD price based on stETH / ETH and ETH / USD feeds.
• Returning price is calculated with 18 decimals.

Governance Payloads

ProposalPayloadStablecoinsPriceAdapter

• Proposal payload for the Aave v2 Ethereum pool.
• For all Aave v2 Ethereum stablecoin assets deploys CLSynchronicityPriceAdapter and sets it as an asset source by calling setAssetSources function on the AaveOracle contract.

ArcProposalPayloadStablecoinsPriceAdapter

• Proposal payload for the Aave Arc pool.
• For all Aave Arc stablecoin assets deploys CLSynchronicityPriceAdapter and sets it as an asset source by calling setAssetSources function on the AaveOracle contract.

Aave v2 Ethereum stablecoin assets and USD price feeds

List of affected Aave v2 Ethereum stablecoin assets and used Chainlink Data Feeds for Asset / USD pair.

Asset	Asset address	Chainlink Data Feed address
USDT	0xdAC17F958D2ee523a2206206994597C13D831ec7	0x3E7d1eAB13ad0104d2750B8863b489D65364e32D
BUSD	0x4Fabb145d64652a948d72533023f6E7A623C7C53	0x833D8Eb16D306ed1FbB5D7A2E019e106B960965A
DAI	0x6B175474E89094C44Da98b954EedeAC495271d0F	0xAed0c38402a5d19df6E4c03F4E2DceD6e29c1ee9
SUSD	0x57Ab1ec28D129707052df4dF418D58a2D46d5f51	0xad35Bd71b9aFE6e4bDc266B345c198eaDEf9Ad94
tUSD	0x0000000000085d4780B73119b644AE5ecd22b376	0xec746eCF986E2927Abd291a2A1716c940100f8Ba
USDC	0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	0x8fFfFfd4AfB6115b954Bd326cbe7B4BA576818f6
GUSD	0x056Fd409E1d7A124BD7017459dFEa2F387b6d5Cd	0xa89f5d2365ce98B3cD68012b6f503ab1416245Fc
USDP	0x8E870D67F660D95d5be530380D0eC0bd388289E1	0x09023c0DA49Aaf8fc3fA3ADF34C6A7016D38D5e3
FRAX	0x853d955aCEf822Db058eb8505911ED77F175b99e	0xB9E1E3A9feFf48998E45Fa90847ed4D467E8BcfD
LUSD	0x5f98805A4E8be255a32880FDeC7F6728C6568bA0	0x3D7aE7E594f2f2091Ad8798313450130d0Aba3a0

Aave v2 ARC stablecoin assets and USD price feeds

List of affected Aave v2 Arc stablecoin assets and used Chainlink Data Feeds for Asset / USD pair.

Asset	Asset address	Chainlink Data Feed address
USDC	0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	0x8fFfFfd4AfB6115b954Bd326cbe7B4BA576818f6

Security

Foundry Tests

CLSynchronicityPriceAdapterFormulaTest

• Validates that formula used in price adapter is correct.
• For TESTS_NUM number of tests, makes mock aggregator with price of asset in i-th test set to $Price(ETH / USD) \over i$. Validates that price returned from the CLSynchronicityPriceAdapter is $1 ETHER /over i$.

PriceChangeTest

• Validates that price difference between price feed for pair Asset / ETH and price from the adapter is less than 2%.

CLSynchronicityPriceAdapterPegToBaseTest

• Validates that formula used in price adapter is correct.

CLwstETHSynchronicityPriceAdapterTest

• Validates that formula used in price adapter is correct.

ProposalPayloadStablecoinsPriceAdapterTest

• Validates that after proposal in Aave v2 Ethereum pool is accepted, all asset sources for stablecoin assets are changed.

ArcProposalPayloadStablecoinsPriceAdapterTest

• Validates that after proposal in Aave v2 Ethereum pool is accepted, all asset sources for stablecoin assets are changed.

Audits

TBD

Setup

Install

To install and execute the project locally, you need:

• npm install : To install prettier for linting.
• forge install : This project is made using Foundry so to run it you will need to install it, and then install its dependencies.

Setup environment

cp .env.example .env

Build

forge build

Test

forge test

Copyright

2022 BGD Labs