地址

• 合约入口地址：https://etherscan.io/address/0x29469395eAf6f95920E59F858042f0e28D98a20B

• 合约实现合约：https://etherscan.io/address/0x97bdb4aed0b50a335a78ed24f68528ce3222af72

• 白皮书：https://www.paradigm.xyz/2023/05/blend

• 审计报告：

https://drive.google.com/file/d/13rmzXIdy138gxPwiGNH8kk-yob4Bjzll/view

• 在途拍卖利率计算公式：https://www.desmos.com/calculator/urasr71dhb

名词

贷款：lien

清算：seize

续借：refinance

拍卖：auction

重点

1. 固定利率，无期限

2. offer数据和lien数据均不上链，只通过mapping映射lienId和lien的hash

3. offer只有lender签名，无服务器签名

4. lender和borrower均可进行refinance，lender refinance时，新的offer利率要比当前并且auctionDuration一样；borrower refinance时，如果新的offer借款不足则要补齐差价

5. 在auction中任何lender都可以做refinance，利率随着拍卖进行时间变化；任何人可以上链撮合一个新的auction和offer，利率随着拍卖进行时间变化；

6. 一个offer的amount如果没有被吃完，可以被吃多次，如10个eth，一个borrower借4 eth，另一个借6 eth。

借贷接口

• borrower执行借贷

function borrow(
        LoanOffer calldata offer,
        bytes calldata signature,
        uint256 loanAmount,
        uint256 collateralTokenId
    )

				/* Lock collateral token. */
        offer.collection.safeTransferFrom(
            msg.sender,
            address(this),
            collateralTokenId
        );

        /* Transfer loan to borrower. */
        pool.transferFrom(offer.lender, msg.sender, loanAmount);

• borrower还贷

function repay(
        Lien calldata lien,
        uint256 lienId
    )

				/* Repay loan to lender. */
        pool.transferFrom(msg.sender, lien.lender, debt);

• lender发起auction

function startAuction(
        Lien calldata lien,
        uint256 lienId
    )
				if (msg.sender != lien.lender) {
            revert Unauthorized();
        }

				仅变更lien中的startAuction，重新计算hash

• lender获取逾期的NFT

function seize(LienPointer[] calldata lienPointers) 

                /* Seize collateral to lender. */
                lien.collection.safeTransferFrom(
                    address(this),
                    lien.lender,
                    lien.tokenId
                );

• lender做refinance

function refinance(
        Lien calldata lien,
        uint256 lienId,
        LoanOffer calldata offer,
        bytes calldata signature
    )

				if (msg.sender != lien.lender) {
            revert Unauthorized();
        }

			/* Interest rate must be at least as good as current. */
        if (
            offer.rate > lien.rate ||
            offer.auctionDuration != lien.auctionDuration
        ) {
            revert InvalidRefinance();
        }

        /* Repay initial loan. */
        pool.transferFrom(offer.lender, lien.lender, debt);

• borrower做refinance

function borrowerRefinance(
        Lien calldata lien,
        uint256 lienId,
        uint256 loanAmount,
        LoanOffer calldata offer,
        bytes calldata signature
    ) 

        if (msg.sender != lien.borrower) {
            revert Unauthorized();
        }

• 任何lender对auction进行refinance

function refinanceAuction(
        Lien calldata lien,
        uint256 lienId,
        uint256 rate
    ) 

        /* Rate must be below current rate limit. */
        uint256 rateLimit = CalculationHelpers.calcRefinancingAuctionRate(
            lien.auctionStartBlock,
            lien.auctionDuration,
            lien.rate
        );
        if (rate > rateLimit) {
            revert RateTooHigh();
        }

				/* Repay the initial loan. */
        pool.transferFrom(msg.sender, lien.lender, debt);

• 任何人执行一个offer的refinance

function refinanceAuctionByOther(
        Lien calldata lien,
        uint256 lienId,
        LoanOffer calldata offer,
        bytes calldata signature
    ) external validateLien(lien, lienId) auctionIsActive(lien) {
        /* Rate must be below current rate limit and auction duration must be the same. */
        uint256 rateLimit = CalculationHelpers.calcRefinancingAuctionRate(
            lien.auctionStartBlock,
            lien.auctionDuration,
            lien.rate
        );
        if (
            offer.rate > rateLimit ||
            offer.auctionDuration != lien.auctionDuration
        ) {
            revert InvalidRefinance();
        }

        /* Repay initial loan. */
        pool.transferFrom(offer.lender, lien.lender, debt);

市场接口

• borrower借钱买

function buyToBorrow(
        LoanOffer calldata offer,
        bytes calldata signature,
        uint256 loanAmount,
        Execution calldata execution
    )

• 买在途再借

function buyToBorrowLocked(
        Lien calldata lien,
        SellInput calldata sellInput,
        LoanInput calldata loanInput,
        uint256 loanAmount
    )

• 买在途

function buyLocked(
        Lien calldata lien,
        SellOffer calldata offer,
        bytes calldata signature
    )

• 卖在途

function takeBid(
        Lien calldata lien,
        uint256 lienId,
        Execution calldata execution
    ) 

        if (
            execution.makerOrder.order.trader == address(this) ||
            msg.sender != lien.borrower
        ) {
            revert Unauthorized();
        }