For example, a preimaging attack that costs trillions of dollars and takes decades to preimage one desired hash value or one message is not practical; one that costs a few thousand dollars and takes a few weeks might be very practical.
例如，一个花费几万亿与数十年来找出一条哈希值或信息的原像攻击是不实际的；而一个仅花费几千块且只需要几周时间的攻击可能是非常实际的。