Nexus Mutual PQ Review

Score: 87%

This is a Nexus Mutual Process Quality Audit completed on 15 September 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 87%, a strong 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

Finding the smart contract addresses was not easy, but not too hard. First I went to the "docs" on the main website, then at the very, very bottom was "Deployed Contract Information". From there, they have a small website that has all of their employment contracts. Since they use upgradable contracts, I suppose this site in a single place within the organization where they update the addresses.

They are available at Address https://nxm.surge.sh/ as indicated in the Appendix. This Audit only covers the contract Claims at address 0x58676340f458b36997608672Be6548c92Ce50714.

Is the code actively being used? (%)

Answer: 100%

Activity is 7 transactions a week for the claims contract, as indicated in the Appendix, but it is in excess of of 1-- for the token, so I will award them 100% rather than 40%.

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

0x58676340f458b36997608672Be6548c92Ce50714 is the Etherscan verified contract address.

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

Answer: 100%

While I did not check every file (because Nexus is quite a big project) to the eight contracts I did check matched perfectly with the labelled "release candidate" branch.

Guidance:

100% All code matches and Repository was clearly labelled 60 % All code matches but no labelled repository. Repository was found manually 30% Almost all code does match perfectly and repository was found manually 0% Most matching Code could not be found

GitHub address : https://github.com/NexusMutual

Deployed contracts in the following file;

Matching Repository: https://github.com/NexusMutual/smart-contracts/tree/release-candidate

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 a 1,045 commits and 15 branches, this is a healthy GitHub.

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

Location: https://nexusmutual.io/

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

Answer: Yes

Location: https://nexusmutual.gitbook.io/docs/docs

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

Answer: 60%

Clearly the descriptions in the "docs" covered a good deal of the logic in the deployed contracts. However, there is no clear association between the text and code. Given this it is very difficult to judge exactly how much is covered. In this situation, a score of 60% is given.

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: 60%

Overall a good level of commenting, using NatSpec. However, detail level is not high.

Code examples are in the Appendix. As per the SLOC, there is 38% 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 clear association between the docs and the code, this has to stay 0%

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: 100%

There are over 14,000 lines of Javascript tests and a 205% code to test ratio. Wow.

How to improve this score

This score can improve by adding tests to fully cover the code. Document what is covered by traceability or test results in the software repository.

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

Answer: 50%

As indicated below the score will be 50%. While it was clear that coverage tests were done, the actual coverage is no displayed publicly.

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

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

Answer: Yes

Test instructions in the GitHub readme

Packaged with the deployed code (Y/N)

Answer: Yes

Report of the results (%)

Answer: 70%

There is a build report from the GitHub TravisCI (link below) which indicates a full build and a pass with the "release-candidate" build. It does not indicate coverage (though clearly coverage was run).

Build report link: https://travis-ci.org/github/somish/NexusMutual/builds/645327529/config

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 indication of formal validation, though this is still a new technology.

Stress Testing environment (%)

Answer: 0%

While I am confident that a proect as involved as this has an active test network, no artifacts indicate this.

Audits

Answer: 100%

Nexus Mutual has two independent detailed audits where the changes were incorporated and witnessed by the auditors in most cases.

Audits in the readme; https://github.com/NexusMutual/smart-contracts

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 Usage

Example Code Appendix

/**
* @dev Calculates total amount that has been used to assess a claim.
* Computaion:Adds acceptCA(tokens used for voting in favor of a claim)
* denyCA(tokens used for voting against a claim) * current token price.
* @param claimId Claim Id.
* @param member Member type 0 -> Claim Assessors, else members.
* @return tokens Total Amount used in Claims assessment.
*/
function getCATokens(uint claimId, uint member) external view returns(uint tokens) {
uint coverId;
(, coverId) = cd.getClaimCoverId(claimId);
bytes4 curr = qd.getCurrencyOfCover(coverId);
uint tokenx1e18 = m1.calculateTokenPrice(curr);
uint accept;
uint deny;
if (member == 0) {
(, accept, deny) = cd.getClaimsTokenCA(claimId);
} else {
(, accept, deny) = cd.getClaimsTokenMV(claimId);
}
tokens = ((accept.add(deny)).mul(tokenx1e18)).div(DECIMAL1E18); // amount (not in tokens)
}
/**
* Iupgradable Interface to update dependent contract address
*/
function changeDependentContractAddress() public onlyInternal {
tk = NXMToken(ms.tokenAddress());
td = TokenData(ms.getLatestAddress("TD"));
tf = TokenFunctions(ms.getLatestAddress("TF"));
tc = TokenController(ms.getLatestAddress("TC"));
p1 = Pool1(ms.getLatestAddress("P1"));
p2 = Pool2(ms.getLatestAddress("P2"));
pd = PoolData(ms.getLatestAddress("PD"));
cr = ClaimsReward(ms.getLatestAddress("CR"));
cd = ClaimsData(ms.getLatestAddress("CD"));
qd = QuotationData(ms.getLatestAddress("QD"));
m1 = MCR(ms.getLatestAddress("MC"));
}
/**
* @dev Updates the pending claim start variable,
* the lowest claim id with a pending decision/payout.
*/
function changePendingClaimStart() public onlyInternal {
uint origstat;
uint state12Count;
uint pendingClaimStart = cd.pendingClaimStart();
uint actualClaimLength = cd.actualClaimLength();
for (uint i = pendingClaimStart; i < actualClaimLength; i++) {
(, , , origstat, , state12Count) = cd.getClaim(i);
if (origstat > 5 && ((origstat != 12) || (origstat == 12 && state12Count >= 60)))
cd.setpendingClaimStart(i);
else
break;
}
}
/**
* @dev Submits a claim for a given cover note.
* Adds claim to queue incase of emergency pause else directly submits the claim.
* @param coverId Cover Id.
*/
function submitClaim(uint coverId) public {
address qadd = qd.getCoverMemberAddress(coverId);
require(qadd == msg.sender);
uint8 cStatus;
(, cStatus, , , ) = qd.getCoverDetailsByCoverID2(coverId);
require(cStatus != uint8(QuotationData.CoverStatus.ClaimSubmitted), "Claim already submitted");
require(cStatus != uint8(QuotationData.CoverStatus.CoverExpired), "Cover already expired");
if (ms.isPause() == false) {
_addClaim(coverId, now, qadd);
} else {
cd.setClaimAtEmergencyPause(coverId, now, false);
qd.changeCoverStatusNo(coverId, uint8(QuotationData.CoverStatus.Requested));
}
}
/**
* @dev Submits the Claims queued once the emergency pause is switched off.
*/
function submitClaimAfterEPOff() public onlyInternal {
uint lengthOfClaimSubmittedAtEP = cd.getLengthOfClaimSubmittedAtEP();
uint firstClaimIndexToSubmitAfterEP = cd.getFirstClaimIndexToSubmitAfterEP();
uint coverId;
uint dateUpd;
bool submit;
address qadd;
for (uint i = firstClaimIndexToSubmitAfterEP; i < lengthOfClaimSubmittedAtEP; i++) {
(coverId, dateUpd, submit) = cd.getClaimOfEmergencyPauseByIndex(i);
require(submit == false);
qadd = qd.getCoverMemberAddress(coverId);
_addClaim(coverId, dateUpd, qadd);
cd.setClaimSubmittedAtEPTrue(i, true);
}
cd.setFirstClaimIndexToSubmitAfterEP(lengthOfClaimSubmittedAtEP);
}

SLOC Appendix

Solidity Contracts

Language

Files

Lines

Blanks

Comments

Code

Complexity

Solidity

22

11528

1535

2773

7220

1217

Comments to Code 2773/ 7220 = 38%

Javascript Tests

Language

Files

Lines

Blanks

Comments

Code

Complexity

JavaScript

32

16356

1355

206

14795

422

Tests to Code 14795 / 7220 = 205%