Yearn Finance Process Quality Review

Score : 66%

This is a Yearn Finance Process Quality Audit completed on 15 August 2020. It was performed using the Process Audit process (version 0.5) and is documented here. The audit was performed by ShinkaRex of Caliburn Consulting. Check out our Telegram.

The final score of the audit is 66%, a pass. The breakdown of the scoring is in Scoring Appendix.

Summary of the Process

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.

  1. Here is my smart contract on the blockchain

  2. You can see it matches a software repository used to develop the code

  3. Here is the documentation that explains what my smart contract does

  4. Here are the tests I ran to verify my smart contract

  5. Here are the audit(s) performed to review my code by third party experts

Disclaimer

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, 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. 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.

Executing Code Verification

This section looks at the code deployed on the Mainnet that gets audited and its corresponding software repository. The document explaining these questions is here. This audit will answer the questions;

  1. Is the executing code address(s) readily available? (Y/N)

  2. Is the code actively being used? (%)

  3. Are the Contract(s) Verified/Verifiable? (Y/N)

  4. Does the code match a tagged version in the code hosting platform? (%)

  5. Is the software repository healthy? (%)

Is the executing code address(s) readily available? (Y/N)

Answer: Yes

It took some looking as the contracts are scattered over several repos in https://github.com/iearn-finance such as vaults, apr_oracle and itoken,

They are available at Address 0x97FF4A1b787ADe6b94cca95b61F79417c673331D as indicated in the Appendix. This Audit only covers the contract yDa2i.sol.

Is the code actively being used? (%)

Answer: 100%

Activity is more than 20 transactions a day, as indicated in the Appendix.

Percentage Score Guidance

100% More than 10 transactions a day 70% More than 10 transactions a week 40% More than 10 transactions a month 10% Less than 10 transactions a month 0% No activity

Are the Contract(s) Verified/Verifiable? (Y/N)

Answer: Yes

0x97FF4A1b787ADe6b94cca95b61F79417c673331D is the Etherscan verified contract address.

Does the code match a tagged version on a code hosting platform? (%)

Answer: 60%

All files matched, but there were no releases, not many branches either.

Guidance:

100% Code matches and Repository was clearly labelled 60 % Code matches but no labelled repository. Repository was found manually 30% Code does match perfectly and repository was found manually 0% Matching Code could not be found

GitHub address : https://github.com/iearn-finance

Deployed contracts in the following file;

Matching Repository: https://github.com/iearn-finance/itoken/tree/master/contracts

How to improve this score

Ensure there is a clearly labelled repository holding all the contracts, documentation and tests for the deployed code. Ensure an appropriately labeled tag exists corresponding to deployment dates. Release tags are clearly communicated.

Is development software repository healthy? (%)

Answer: 100%

With 292 commits and 5 branches in https://github.com/iearn-finance/iearn-finance, it can be considered healthy.

Documentation

This section looks at the software documentation. The document explaining these questions is here.

Required questions are;

  1. Is there a whitepaper? (Y/N)

  2. Are the basic application requirements documented? (Y/N)

  3. Do the requirements fully (100%) cover the deployed contracts? (%)

  4. Are there sufficiently detailed comments for all functions within the deployed contract code (%)

  5. Is it possible to trace software requirements to the implementation in code (%)

Is there a whitepaper? (Y/N)

Answer: Yes

While a white paper (by that name) does not exist, there is a clear sequence of medium articles explaining the functions of yearn.finance that meet the need and are more approachable.

Location: https://medium.com/iearn/yfi-df84573db81

Are the basic application requirements documented? (Y/N)

Answer: No

docs.yearn.finance talks about how the protocol is used but does not relate it back to the software at all. There is no documentation of the software

How to improve this score

Write the document based on the deployed code. For guidance, refer to the SecurEth System Description Document.

Do the requirements fully (100%) cover the deployed contracts? (%)

Answer: 0%

There is no code documentation

How to improve this score

This score can improve by adding content to the requirements document such that it comprehensively covers the requirements. For guidance, refer to the SecurEth System Description Document . Using tools that aid traceability detection will help.

Are there sufficiently detailed comments for all functions within the deployed contract code (%)

Answer: 30%

Comments are used rarely to impart important small pieces of information to make understanding the code easier.

Code examples are in the Appendix. As per the SLOC, there is 6% commenting to code.

How to improve this score

This score can improve by adding comments to the deployed code such that it comprehensively covers the code. For guidance, refer to the SecurEth Software Requirements.

Is it possible to trace requirements to the implementation in code (%)

Answer: 0%

As there is no code documentation or requirements, tracing these to the code is not possible.

Guidance: 100% - Clear explicit traceability between code and documentation at a requirement level for all code 60% - Clear association between code and documents via non explicit traceability 40% - Documentation lists all the functions and describes their functions 0% - No connection between documentation and code

How to improve this score

This score can improve by adding traceability from requirements to code such that it is clear where each requirement is coded. For reference, check the SecurEth guidelines on traceability.

Testing

This section looks at the software testing available. It is explained in this document. This section answers the following questions;

  1. Full test suite (Covers all the deployed code) (%)

  2. Code coverage (Covers all the deployed lines of code, or explains misses) (%)

  3. Scripts and instructions to run the tests (Y/N)

  4. Packaged with the deployed code (Y/N)

  5. Report of the results (%)

  6. Formal Verification test done (%)

  7. Stress Testing environment (%)

Is there a Full test suite? (%)

Answer: 60%

The test contracts are in the audit repository. The test package seems very comprehensive. However the lack of unit, integration and e2e tests was noted in the overview of the Quantstamp audit and for that reason only 60% score is indicated.

Code coverage (Covers all the deployed lines of code, or explains misses) (%)

Answer: 50%

No reports or indication of coverage so 50% as per below.

Guidance: 100% - Documented full coverage 99-51% - Value of test coverage from documented results 50% - No indication of code coverage but clearly there is a reasonably complete set of tests 30% - Some tests evident but not complete 0% - No test for coverage seen

How to improve this score

This score can improve by adding tests achieving full code coverage. A clear report and scripts in the software repository will guarantee a high score.

Scripts and instructions to run the tests (Y/N)

Answer: No

Yearns code is spread out to various repos, with the tests in another. There was no documented set of build and test process that I could see.

How to improve this score

Add the scripts to the repository and ensure they work. Ask an outsider to create the environment and run the tests. Improve the scripts and docs based on their feedback.

Packaged with the deployed code (Y/N)

Answer: Yes

Report of the results (%)

Answer: 0%

No test report was evident.

How to improve this score

Add a report with the results. The test scripts should generate the report or elements of it.

Formal Verification test done (%)

Answer: 0%

No formal verification was evident.

Stress Testing environment (%)

Answer: 0%

While I am quite sure there was extensive testnet usage to bring something as big as yearn to life, I can see no evidence of it.

Audits

Answer: 100%

As indicated in the audits repo, there are multiple audits with corrections implemented.

Guidance:

  1. Multiple Audits performed before deployment and results public and implemented or not required (100%)

  2. Single audit performed before deployment and results public and implemented or not required (90%)

  3. Audit(s) performed after deployment and no changes required. Audit report is public. (70%)

  4. No audit performed (20%)

  5. Audit Performed after deployment, existence is public, report is not public and no improvements deployed OR smart contract address' not found, question 1 (0%)

Appendices

Author Details

The author of this audit is Rex of Caliburn Consulting.

Email : rex@defisafety.com Twitter : @defisafety

I started with Ethereum just before the DAO and that was a wonderful education. It showed the importance of code quality. The second Parity hack also showed the importance of good process. Here my aviation background offers some value. Aerospace knows how to make reliable code using quality processes.

I was coaxed to go to EthDenver 2018 and there I started SecuEth.org with Bryant and Roman. We created guidelines on good processes for blockchain code development. We got EthFoundation funding to assist in their development.

Process Quality Audits are an extension of the SecurEth guidelines that will further increase the quality processes in Solidity and Vyper development.

Career wise I am a business development manager for an avionics supplier.

Scoring Appendix

Executing Code Appendix

Code Used Appendix

Example Code Appendix

contract yDAI is ERC20, ERC20Detailed, ReentrancyGuard, Structs {
using SafeERC20 for IERC20;
using Address for address;
using SafeMath for uint256;
uint256 public pool;
address public token;
address public compound;
address public fulcrum;
address public aave;
address public aaveToken;
address public dydx;
uint256 public dToken;
address public apr;
enum Lender {
NONE,
DYDX,
COMPOUND,
AAVE,
FULCRUM
}
Lender public provider = Lender.NONE;
constructor () public ERC20Detailed("iearn DAI", "yDAI", 18) {
token = address(0x6B175474E89094C44Da98b954EedeAC495271d0F);
apr = address(0xdD6d648C991f7d47454354f4Ef326b04025a48A8);
dydx = address(0x1E0447b19BB6EcFdAe1e4AE1694b0C3659614e4e);
aave = address(0x24a42fD28C976A61Df5D00D0599C34c4f90748c8);
fulcrum = address(0x493C57C4763932315A328269E1ADaD09653B9081);
aaveToken = address(0xfC1E690f61EFd961294b3e1Ce3313fBD8aa4f85d);
compound = address(0x5d3a536E4D6DbD6114cc1Ead35777bAB948E3643);
dToken = 3;
approveToken();
}
// Quick swap low gas method for pool swaps
function deposit(uint256 _amount)
external
nonReentrant
{
require(_amount > 0, "deposit must be greater than 0");
pool = _calcPoolValueInToken();
IERC20(token).safeTransferFrom(msg.sender, address(this), _amount);
// Calculate pool shares
uint256 shares = 0;
if (pool == 0) {
shares = _amount;
pool = _amount;
} else {
shares = (_amount.mul(_totalSupply)).div(pool);
}
pool = _calcPoolValueInToken();
_mint(msg.sender, shares);
}
// No rebalance implementation for lower fees and faster swaps
function withdraw(uint256 _shares)
external
nonReentrant
{
require(_shares > 0, "withdraw must be greater than 0");
uint256 ibalance = balanceOf(msg.sender);
require(_shares <= ibalance, "insufficient balance");
// Could have over value from cTokens
pool = _calcPoolValueInToken();
// Calc to redeem before updating balances
uint256 r = (pool.mul(_shares)).div(_totalSupply);
_balances[msg.sender] = _balances[msg.sender].sub(_shares, "redeem amount exceeds balance");
_totalSupply = _totalSupply.sub(_shares);
emit Transfer(msg.sender, address(0), _shares);
// Check balance
uint256 b = IERC20(token).balanceOf(address(this));
if (b < r) {
_withdrawSome(r.sub(b));
}

SLOC Appendix

Solidity Contracts

Language

Files

Lines

Blanks

Comments

Code

Complexity

Solidity

44

20952

2884

1008

17060

2213

Comments to Code 1008/ 17060 = 6%

Javascript Tests

Language

Files

Lines

Blanks

Comments

Code

Complexity

JavaScript

8

2012

532

122

1358

59

Tests to Code 1358 / 1959 = 70%