Project.sol and Community.sol have no way to revoke a hash in approvedHashes

[code423n4]

Lines of code

https://github.com/code-423n4/2022-08-rigor/blob/5ab7ea84a1516cb726421ef690af5bc41029f88f/contracts/Community.sol#L501-L506
https://github.com/code-423n4/2022-08-rigor/blob/5ab7ea84a1516cb726421ef690af5bc41029f88f/contracts/Project.sol#L108-L115

Vulnerability details

Impact

User is unable to revoke previously approved hash

Proof of Concept

If user reconsiders or notices something malicious about the hash after signing, they should be able to revoke the hash. For example the user approves a hash only to find out later that the hash has been spoofed and they weren't approving what they thought they were. To protect themselves the user should be able to revoke approval, otherwise it may lead to loss of funds or access.

Tools Used

Recommended Mitigation Steps

Add the following function:

function revokeHash(bytes32 _hash) external virtual {
    approvedHashes[_msgSender()][_hash] = false;
}

[parv3213]

Duplicate of #86

[parv3213]

Duplicate of #86

This is a separate issue and not a duplicate. I do not find it essential to revoke a hash. As off-chain signatures can never be marked as invalid, adding this feature for on-chain signatures makes no sense.