Hedgey Token Lockup and Vesting Plans

1 Executive Summary

This report presents the results of our engagement with Hedgey to review Token Lockup and Vesting Plans.

The review was conducted over four weeks, from June 26, 2023 to July 21, 2023, by Chingiz Mardanov and David Braun. A total of 29 person-days were spent.

2 Scope

Our review focused on the commit hash 6a5ff58c2e83015b83c8de15f1cc61e9ac58f2c7. The list of files in scope can be found in the Appendix.

2.1 Update: August 3rd - Mitigations

The report was updated to reflect mitigations implemented in commit hash f4299cdba5e863c9ca2d69a3a7dd554ac34af292, 3544f6ad5a586bcbbd31f1d136a054bd548d0c3a, 02512711aff5ff6dfcdecba2b89c82b54e0a6db8, 135297b9a7017d1eb9a7ee473c6fe27ce166cbe7 and 8c7679c7526c29980c6255127c0cd0ba85d000fa. An additional 10 person days (in the week of July 31 - August 4) were spent, focusing on reviewing changes that were implemented to address our specific findings. We have also included the new file PlanDelegator.sol into the scope of the review. As with every project that undergoes significant changes it is recommended to conduct a complete re-assessment of the changed system.

2.2 Objectives

Together with the Hedgey team, we identified the following priorities for our review:

1. Correctness of the implementation, consistent with the intended functionality and without unintended edge cases.
2. Identify known vulnerabilities particular to smart contract systems, as outlined in our Smart Contract Best Practices, and the Smart Contract Weakness Classification Registry.
3. Reentrancy Attacks
4. Errors with segmenting and combining lockup plans that could cause a user to lose out on funds, or receive additional funds they were not meant to get
5. Errors with segmenting and combining lockup plans that allow someone’s to unlock their tokens earlier than scheduled initially
6. Errors with On-chain voting vaults that would allow someone to pull their tokens from the contract without authorization
7. Calculation errors from the time lock library

2.3 Update: August 3rd - Mitigations

The report was updated to reflect mitigations implemented for the findings. An additional 10 person days (in the week of July 31 - August 4) were spent to conduct the review, focusing on reviewing the changes that were implemented addressing the specific findings. We have also included the PlanDelegator.sol contract into the scope of the review.

3 Security Specification

This section describes, from a security perspective, the expected behavior of the system under audit. It is not a substitute for documentation. The purpose of this section is to identify specific security properties that were validated by the audit team.

3.1 Actors

The relevant actors are listed below with their respective abilities:

• Vesting or a Lockup Plan Holder - also the recipient of the vested tokens. Wallet or contract that is the owner of a specific ERC-721 token.
• Vesting Admin - address that is in certain cases capable of moving the ERC-721 plan on behalf of the holder as well as revoke the plan.
• Vesting Plan - a linear token unlock plan that is revokable by the vesting admin. Can also be only transferred by vesting admin when that was enabled on creation.
• Voting Vesting Plan - same as vesting plan but with additional Voting Vaults to support on-chain governance.
• Lockup Plan - linear token unlock plan, that can be transferred, segmented and combined again.
• Voting Lockup Plan - same as lockup plan but with additional of Voting Vaults to support on-chain governance.
• Soul Bound Lockup Plan - same as lockup plan but without an ability to transfer it.

3.2 Trust Model

We are delighted to highlight the inherent decentralized nature of the Hedgey platform. Upon conducting a comprehensive review of the contracts, we find it commendable that no upgradeability functionality is incorporated, a decision which aligns well with our principles at Diligence.

However, it is crucial to address one centralization risk that warrants attention. This concern pertains to the vesting plans that allow the adminTransferOBO flag to be enabled. In such instances, the vesting plan’s administrator gains the ability to transfer tokens on behalf of the recipient, potentially leading to the loss of vested but unclaimed tokens. While we understand that this measure is intended to safeguard less experienced users from the risk of losing access to their vesting wallets, it also introduces the possibility of malicious activities.

4 Findings

Each issue has an assigned severity:

• Minor issues are subjective in nature. They are typically suggestions around best practices or readability. Code maintainers should use their own judgment as to whether to address such issues.
• Medium issues are objective in nature but are not security vulnerabilities. These should be addressed unless there is a clear reason not to.
• Major issues are security vulnerabilities that may not be directly exploitable or may require certain conditions in order to be exploited. All major issues should be addressed.
• Critical issues are directly exploitable security vulnerabilities that need to be fixed.

function setupVoting(uint256 planId) external nonReentrant returns (address votingVault) {
  votingVault = _setupVoting(msg.sender, planId);

function _setupVoting(address holder, uint256 planId) internal returns (address) {
  require(ownerOf(planId) == holder, '!owner');

function segmentPlan(
  uint256 planId,
  uint256[] memory segmentAmounts
) external nonReentrant returns (uint256[] memory newPlanIds) {
  newPlanIds = new uint256[](segmentAmounts.length);
  for (uint256 i; i < segmentAmounts.length; i++) {
    uint256 newPlanId = _segmentPlan(msg.sender, planId, segmentAmounts[i]);

function _segmentPlan(address holder, uint256 planId, uint256 segmentAmount) internal returns (uint256 newPlanId) {
  require(ownerOf(planId) == holder, '!owner');

function revokePlans(uint256[] memory planIds) external nonReentrant {
  for (uint256 i; i < planIds.length; i++) {
    _revokePlan(msg.sender, planIds[i]);

function _revokePlan(address vestingAdmin, uint256 planId) internal {
  Plan memory plan = plans[planId];
  require(vestingAdmin == plan.vestingAdmin, '!vestingAdmin');

function _revokePlan(address vestingAdmin, uint256 planId) internal {
  Plan memory plan = plans[planId];
  require(vestingAdmin == plan.vestingAdmin, '!vestingAdmin');
  (uint256 balance, uint256 remainder, ) = planBalanceOf(planId, block.timestamp, block.timestamp);
  require(remainder > 0, '!Remainder');
  address holder = ownerOf(planId);
  delete plans[planId];
  _burn(planId);
  TransferHelper.withdrawTokens(plan.token, vestingAdmin, remainder);
  TransferHelper.withdrawTokens(plan.token, holder, balance);
  emit PlanRevoked(planId, balance, remainder);
}

function _revokePlan(address vestingAdmin, uint256 planId) internal {
  Plan memory plan = plans[planId];
  require(vestingAdmin == plan.vestingAdmin, '!vestingAdmin');
  (uint256 balance, uint256 remainder, ) = planBalanceOf(planId, block.timestamp, block.timestamp);
  require(remainder > 0, '!Remainder');
  address holder = ownerOf(planId);
  delete plans[planId];
  _burn(planId);
  address vault = votingVaults[planId];
  if (vault == address(0)) {
    TransferHelper.withdrawTokens(plan.token, vestingAdmin, remainder);
    TransferHelper.withdrawTokens(plan.token, holder, balance);
  } else {
    delete votingVaults[planId];
    VotingVault(vault).withdrawTokens(vestingAdmin, remainder);
    VotingVault(vault).withdrawTokens(holder, balance);
  }
  emit PlanRevoked(planId, balance, remainder);
}

function withdrawTokens(address to, uint256 amount) external onlyController {
    TransferHelper.withdrawTokens(token, to, amount);
    if (IERC20(token).balanceOf(address(this)) == 0) selfdestruct;
}

function transferTokens(
  address token,
  address from,
  address to,
  uint256 amount
) internal {
  uint256 priorBalance = IERC20(token).balanceOf(address(to));
  require(IERC20(token).balanceOf(msg.sender) >= amount, 'THL01');

/// @notice function to calculate the total periods in a given plan based on the rate and amount
function totalPeriods(uint256 rate, uint256 amount) internal pure returns (uint256 periods) {
  periods = amount / rate;
}

// Mapping if a token has been transferred
mapping(uint256 => bool) public wasTransferred;

require(index < ERC721.balanceOf(owner), 'ERC721Enumerable: owner index out of bounds');

require(index < totalSupply(), 'ERC721Enumerable: global index out of bounds');

function transferFrom(address from, address to, uint256 tokenId) public override(IERC721, ERC721) {

function _safeTransfer(address from, address to, uint256 tokenId, bytes memory data) internal override {

function _transfer(address from, address to, uint256 tokenId) internal virtual override {

function redeemPlans(uint256[] memory planIds) external nonReentrant {

function revokePlans(uint256[] memory planIds) external nonReentrant {

function segmentPlan(
  uint256 planId,
  uint256[] memory segmentAmounts
) external nonReentrant returns (uint256[] memory newPlanIds) {

Appendix 1 - Files in Scope

This audit covered the following files:

Appendix 2 - Disclosure

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