[Ethereum co-founder Vitalik Buterin looks back on initial design regrets] Ethereum co-founder Vitalik Buterin recently shared some of his reflections on Ethereum's initial design at the ETHBerlin event. He said that from the development of the Ethereum virtual machine to smart contracts to the proof-of-stake consensus mechanism, there are things he could have done differently. He believes that Ethereum's original EVM design chose 256-bit processing instead of 64 or 32 bits, which made the design too complex and inefficient, and could generate a lot of redundant data on the blockchain even when performing simple tasks. In addition, he said that Ethereum should have switched from the proof-of-work consensus mechanism to proof-of-stake earlier. He also mentioned that the automatic log of Ethereum transfers should have existed from the beginning, rather than being changed later through EIP-7708. Finally, he said that if he chose again, he would use SHA-2 to encrypt Ethereum instead of the current encryption algorithm called Keccak.