Meridio Contracts

ConsenSys Diligence Audit Report from October 5, 2018

This repo represents the contracts that make up the Meridio Asset Token ecosystem.

For more information about Meridio, visit Meridio.co

Setup

This repo is setup to use Truffle, so you can run standard commands:

truffle test
truffle migrate
truffle compile

Other Commands that are available:

npm run coverage - Generates the Solidity Test Coverage report
npm run test - Runs truffle test suite
npm run hint - Generates solhint report
npm run myth - Recompiles contracts and runs Mythril for Truffle

Environment Variables:

INFURA_PROJECT_ID - (Legacy) Infura ID for connecting to infura rinkeby node
MNEMONIC_PHRASE - mnemonic phrase to give access to the wallet for launching on Rinkeby

Contract Descriptions

Third Party contracts

`FakeDai`

This is a copy of the Dai contract that Meridio uses in its test environments to mock interactions with Mainnet Dai.

`Exchange`

This is a copy of the Airswap Exchange contract that Meridio uses for P2P swaps between AssetTokens and Dai.

Token

This is a modified ERC20 that represents the core of the Meridio token ecosystem. It has modules on it to validate transfers and is used to track the tokens for each asset in the Meridio system. It will be launched as a Singleton and each Token in the system will be a proxy that references this implementation. When deploying the singleton, the deployer should ensure that the implementation gets initialized. The ProxyTokenFactory is recommended for launching new individual tokens as that will initialize them in the initial transaction. Key Modifications to ERC20 standard:

Adding canSend checks before allowing transfer, transferFrom, forceTransfer functions to run
Adding forceTranfer function to allow the owner to move tokens from one address to another in compliance with the canSend parameters.
Allowing owner to mint/burn to/from any address
Allow owner to addModule/removeModule to control the parameters of canSend

Inheritance Chain:

Proxy

`OwnedUpgradeabilityProxy`

This contract combines an upgradeability proxy with basic authorization control functionalities Source https://github.com/zeppelinos/labs/blob/master/upgradeability_using_unstructured_storage/contracts/OwnedUpgradeabilityProxy.sol Interface Reference: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-897.md Implementation notes:

constructors will not work, the proxied contract must be initialized after proxying. That is what the upgradeToAndCall function is for.
if you do not inherit your version n-1 into version n, you will overwrite memory slots with the new contract.
if you inherit version n-1 into version n, you will preserve memory slots including the _initialized flag.
Therefore each new contract that needs to be initialized should have its own _initialized flag and function.
ProxyOwner can change implementation reference and reassign ownership (of the proxy)

Inheritance Chain:

UpgradeabilityProxy>Proxy>ERCProxy

Factories

`ProxyTokenFactory`

This singleton launches a new proxy contract and points it to the implementation it is given. It then assigns ownership of the Token (impl) and the Proxy to the msg.sender

Inheritance Chain:

Note: Imports OwnedUpgradeabilityProxy.sol as ProxyToken

Modules

`BlacklistValidator`

This TransferValidator contract reverts transfers if the to address is true in the blacklist mapping.

Permissions:

The owner of the contract can add/remove addresses from the blacklist.

Inheritance Chain:

`InvestorCapValidator`

This TransferValidator contract reverts transfers if the transfer would cause there to be too many investors. InvestorCount and InvestorCap are tracked as state on this contract. There is one InvestorCount per msg.sender that interacts with this contract and a single InvestorCap. (In the case of a token transfer msg.sender is the token contract.)

Logic:

If to has a balance of 0 and from will not have a balance of 0 after the trade then increase investorCount for msg.sender. If from will have a balance of 0 and to already has a balance of token, then decrease investorCount for msg.sender. Report false if a trade would cause investorCount to be greater than investorCap.

Permissions:

The owner of the contract can manually update the investorCount for any address and can set the InvestorCap.

Inheritance Chain:

`InvestorMinValidator`

This TransferValidator contract reverts transfers if the transfer would cause there to be too few investors. InvestorCount and InvestorMin are tracked as state on this contract. There is one InvestorCount per msg.sender that interacts with this contract and a single InvestorMin. (In the case of a token transfer msg.sender is the token contract.)

Logic:

Permissions:

The owner of the contract can manually update the investorCount for any address and can set the InvestorMin.

Inheritance Chain:

`LockUpPeriodValidator`

This TransferValidator contract reverts transfers if the transfer would occur before the specified openingTime (compared against block.timestamp).

Permissions:

The owner of the contract can manually update the openingTime.

Inheritance Chain:

`MaxAmountValidator`

This TransferValidator contract reverts transfers if the transfer would increase the to address's balance above a maxAmount.

Permissions:

The owner of the contract can manually update the maxAmount.

Inheritance Chain:

`PausableValidator`

This TransferValidator contract reverts transfers if the validator is paused.

Permissions:

The owner of the contract can pause/unpause the contract.

Inheritance Chain:

`SenderBlacklistValidator`

This TransferValidator contract reverts transfers if the from address is true in the blacklist mapping.

Permissions:

The owner of the contract can add/remove addresses from the blacklist.

Inheritance Chain:

`SenderWhitelistValidator`

This TransferValidator contract reverts transfers if the from address is false in the whitelist mapping.

Permissions:

The owner of the contract can add/remove addresses from the whitelist.

Inheritance Chain:

`WhitelistValidator`

This TransferValidator contract reverts transfers if the to address is false in the whitelist mapping.

Permissions:

The owner of the contract can add/remove addresses from the whitelist.

Inheritance Chain:

Other

`DistributionIssuer`

This is a singleton contract that allows anyone to send many ERC20 compliant token transfers of various amounts to various payees. The sender must have approved the contract to transferFrom on its behalf beforehand.

`MeridioCrowdsale`

This is a crowdsale contract based on openzeppelin contracts. It allows for the purchasing of AssetTokens with ETH via transferFrom function. It has a conversion rate and openingTime/closingTime. The Owner can update the Rate as needed to adjust for price fluxuations in ETH.

Inheritance Chain:

`SimpleLinkRegistry`

This is a singleton contract that allows anyone to add key/value pairs to any “subject” smart contract address. The keys are meant to be simple identifiers, and the value is a string intended to be a link to HTTP or IPFS accessible data.

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