Decentralized Music Chain security record

In the contract `DMCCOIN` the `defaultOperators` and any other authorized `operator` have authority over the following functions for a holder provided they are not revoked: - `operatorSend()` - `operatorBurn()` Any compromise to the `defaultOperators` or `operator` accounts, while they are not revoked by a user, may allow a hacker to take advantage of this authority and send or burn tokens without the approval of the holder.

All `DMCC` tokens are sent to the contract deployer when deploying the contract. This is a potential centralization risk as the deployer can distribute `DMCC` tokens without the consensus of the community.

The approval function of the ERC20 standard possesses a well-known vulnerability whereby two consecutive approvals can be exploited to instead “reset” the approval by consuming the approval that is meant to be replaced with a new one.

As per the ERC777 standard, the contract deployer can set a list of default operators who can spend and/or burn a holder tokens. However, the default operators can be revoked by the token holder.

One or more parameters with `memory` data location are never modified in their functions and those functions are never called internally within the contract. Thus, their data location can be changed to `calldata` to avoid the gas consumption copying from calldata to memory. - `send()` has the memory location parameter `data`; - `burn()` has the memory location parameter `data`; - `operatorSend()` has memory location parameters `data` and `operatorData`; - `operatorBurn()` has memory location parameters `data` and `operatorData`.

We would like to ensure that the team and any of the users of these tokens are aware of potential issues with protocols that are not designed to interact with ERC777 tokens. Due to the hooks implemented in the token, reentrancy is possible in protocols that do not account for these hooks, which can cause significant loss for the token holders.

The following function can use unchecked blocks to save gas on each call: - In the function `_mint()`, the increase to the account balance can be placed in an unchecked block. This is because the balances can never exceed the total supply, which is checked above it. - In the function `_burn()`, the decrease to the total supply can be placed in an unchecked block. This is because the amount is less than or equal to the account balance which must be less than or equal to the total supply. - In the function `_move()`, the increase to the `to` balance can be placed in an unchecked block. This is because the sum of all balances is capped by the total supply, and the sum is preserved in this operation as the same amount that is decremented is incremented.

The contracts cited have an unlocked compiler version. An unlocked compiler version in the source code of the contract permits the user to compile it at or above a particular version. This, in turn, leads to differences in the generated bytecode between compilations due to differing compiler version numbers. This can lead to ambiguity when debugging, as compiler specific bugs may occur in the codebase that would be hard to identify over a span of multiple compiler versions rather than a specific one.