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PASS
The final review score is indicated as a percentage. The percentage is calculated as Achieved Points due to MAX Possible Points. For each element the answer can be either Yes/No or a percentage. For a detailed breakdown of the individual weights of each question, please consult this document.
Very simply, the audit looks for the following declarations from the developer's site. With these declarations, it is reasonable to trust the smart contracts.
This report is for informational purposes only and does not constitute investment advice of any kind, nor does it constitute an offer to provide investment advisory or other services. Nothing in this report shall be considered a solicitation or offer to buy or sell any security, token, future, option or other financial instrument or to offer or provide any investment advice or service to any person in any jurisdiction. Nothing contained in this report constitutes investment advice or offers any opinion with respect to the suitability of any security, and the views expressed in this report should not be taken as advice to buy, sell or hold any security. The information in this report should not be relied upon for the purpose of investing. In preparing the information contained in this report, we have not taken into account the investment needs, objectives and financial circumstances of any particular investor. This information has no regard to the specific investment objectives, financial situation and particular needs of any specific recipient of this information and investments discussed may not be suitable for all investors.
Any views expressed in this report by us were prepared based upon the information available to us at the time such views were written. The views expressed within this report are limited to DeFiSafety and the author and do not reflect those of any additional or third party and are strictly based upon DeFiSafety, its authors, interpretations and evaluation of relevant data. Changed or additional information could cause such views to change. All information is subject to possible correction. Information may quickly become unreliable for various reasons, including changes in market conditions or economic circumstances.
This completed report is copyright (c) DeFiSafety 2023. Permission is given to copy in whole, retaining this copyright label.
This section looks at the code deployed on the relevant chain that gets reviewed and its corresponding software repository. The document explaining these questions is here.
1. Are the smart contract addresses easy to find? (%)
2. How active is the primary contract? (%)
Contract Swap Router V1 is used 12 times a day, as indicated in the Appendix.
3. Does the protocol have a public software repository? (Y/N)
Impossible Finance uses GitHub.
4. Is there a development history visible? (%)
At 313 commits and 26 branches, we didn't know a development history like this was possible.
5. Is the team public (not anonymous)?
Their team is public, although only a handful of names were identified. Where we found the team is documented in our team appendix at the end of this report.
This section looks at the software documentation. The document explaining these questions is here.
6. Is there a whitepaper? (Y/N)
Location: https://gateway.pinata.cloud/ipfs/QmSXzevkMPU3z2nZFthEvzdzwpbXDR8Em62XqkKw8g4hTR/Impossible%20Finance%20IDIA%20Official%20Whitepaper.pdf
7. Is the protocol's software architecture documented? (Y/N)
Impossible's software architecture is documented in written form here.
8. Does the software documentation fully cover the deployed contracts' source code? (%)
Impossible Finance documents the software functions of its most major smart contracts here.
9. Is it possible to trace the documented software to its implementation in the protocol's source code? (%)
There is clear but implicit traceability between the software documentation available and implemented code. The score can be improved by linking software function documentation to the corresponding code on Github.
10. Has the protocol tested their deployed code? (%)
Impossible's TtC coverage is 174%. However, it is important to note that testing was only found for the launchpad contracts, but not for the staking or trading ones. Nevertheless, Launchpad is Impossible's main offering and it is adequately tested as per our standards.
11. How covered is the protocol's code? (%)
No test for coverage seen. However, Impossible does have some solid Launchpad testing. As such, 50% will be given here.
12. Does the protocol provide scripts and instructions to run their tests? (Y/N)
Impossible provides scripts for their Launchpad tests here. Do note however that scripts are not provided for swaps/staking since the testing for these strapiucts is effectively nonexistent.
13. Is there a detailed report of the protocol's test results?(%)
No testing reports/CI found in their repos or "Actions" tab.
14. Has the protocol undergone Formal Verification? (Y/N)
Impossible Finance has not undergone formal verification.
15. Were the smart contracts deployed to a testnet? (Y/N)
Evidence of Impossible's Kovan testnet usage was found here.
This section looks at the 3rd party software audits done. It is explained in this document.
16. Is the protocol sufficiently audited? (%)
Impossible Finance has been audited multiple times both pre-deployment and post deployment. Audit reports can be found here.
17. Is the bounty value acceptably high (%)
Impossible Finance offers an active bug bounty of $94K. In addition, the bounty will also payout 10% of the funds at risk within a found attack vector. If a bug is found that would cause the loss of Impossible's entire TVL, the whitehat hacker would effectively get paid 10% of Impossible's TVL.
This section covers the documentation of special access controls for a DeFi protocol. The admin access controls are the contracts that allow updating contracts or coefficients in the protocol. Since these contracts can allow the protocol admins to "change the rules", complete disclosure of capabilities is vital for user's transparency. It is explained in this document.
18. Is the protocol's admin control information easy to find?
Admin control information is documented at this location, and can easily be found.
19. Are relevant contracts clearly labelled as upgradeable or immutable? (%)
Impossible clearly identifies their smart contracts as immutable here.
20. Is the type of smart contract ownership clearly indicated? (%)
Ownership is MultiSig and clearly indicated in this location.
21. Are the protocol's smart contract change capabilities described? (%)
Impossible smart contracts are immutable at the core level, and smart contract change capabilities are described here at a granular level.
22. Is the protocol's admin control information easy to understand? (%)
Impossible's admin control information is easy to understand due to the clear and explicit mentions of immutability.
23. Is there sufficient Pause Control documentation? (%)
Impossible's core protocol is immutable, but granular parameters such as trading pairs can be paused.
24. Is there sufficient Timelock documentation? (%)
Since Impossible is immutable, they have no need for a core timelock. However, any swap changes incur a block delay on the blockchain, which effectively act as a time delay for swap upgrades. In addition, Impossible can retrieve funds from the launchpad in the event of an emergency, but this function is initially locked for months. Furthermore, "The admin does not have any ability to be able to take custody of users funds, and that fees also have a max limit of what they can be set to to prevent the multisig from raising fees to 100% to hurt users or drain any protocol activities. ".
25. Is the Timelock of an adequate length? (Y/N)
Timelock length for the launchpad is enacted months after the start of a launchpad.
This section goes over the documentation that a protocol may or may not supply about their Oracle usage. Oracles are a fundamental part of DeFi as they are responsible for relaying tons of price data information to thousands of protocols using blockchain technology. Not only are they important for price feeds, but they are also an essential component of transaction verification and security. These questions are explained in this document.
26. Is the protocol's Oracle sufficiently documented? (%)
Impossible does not use oracles due to all pool prices being "calculated directly from the supply of tokens in the swap itself. There are no other derivatives or price feed reliances in the Impossible Finance ecosystem" that would require a price feed oracle.
27. Is front running mitigated by this protocol? (Y/N)
The Impossible launchpad does have any time preference, meaning that there are no front-running opportunities there. Moreover, the Impossible swap has an asymmetric boost - which reduces slippage due to higher liquidity parameters. All this information is readily available here.
28. Can flashloan attacks be applied to the protocol, and if so, are those flashloan attack risks mitigated? (Y/N)
Impossible details how they mitigate the feasibility of liquidity exploits by determining allocation as proportional to stake amount held over time here.
1/**
2 *Submitted for verification at BscScan.com on 2020-11-29
3*/
4
5// File: @uniswap/v2-core/contracts/interfaces/IStableXFactory.sol
6
7pragma solidity >=0.5.0;
8
9interface IStableXFactory {
10 event PairCreated(address indexed token0, address indexed token1, address pair, uint);
11
12 function feeTo() external view returns (address);
13 function feeToSetter() external view returns (address);
14
15 function getPair(address tokenA, address tokenB) external view returns (address pair);
16 function allPairs(uint) external view returns (address pair);
17 function allPairsLength() external view returns (uint);
18
19 function createPair(address tokenA, address tokenB) external returns (address pair);
20
21 function setFeeTo(address) external;
22 function setFeeToSetter(address) external;
23}