THREAT - Election will not be able to reveal the result if anyone submits a fake vote.

[chenchanglew]

Scenario

If a ballot fails to decrypt during the decryption process, it will return an error and make the whole decryption step fail. This will make the smart contracts will not accept the transaction which means the decryption process will never succeed.

Source

contracts/evoting/evoting.go combineShares()

for j := 0; j < ballotSize; j++ {
    chunk, err := decrypt(i, j, allPubShares, form.PubsharesUnits.Indexes)
    if err != nil {
        return xerrors.Errorf("failed to decrypt (K, C): %v", err)
    }
...
}

Breaking Property

Availability

Risk

CVSS Score: 5.7/10

Mitigation

Ignore the ballot which has a decryption error, just assume it is an empty ballot during the reveal result.

Target

Add some unit-test related to decrypt an error ballot.