[Vitalik: 51% attacks cannot rewrite blocks, but off-chain trust introduces new risks] According to a report by Golden Finance, Ethereum co-founder Vitalik Buterin emphasized in a post that the key security property of blockchain lies in the fact that even in the event of a 51% attack, invalid blocks cannot be made valid. Therefore, collusion among 51% of validators or software failures cannot steal user assets. However, he warned that if reliance on validators to perform off-chain tasks, which are beyond the control of the chain itself, begins, then 51% of validators could collude to provide incorrect results, leaving users without protection mechanisms.