It also is probably what a number of reporters said earlier this month when they were permitted to see a machine that will be sent to the planet Mars.

VOA: special.2011.04.26

If you have some plain text, some message that you want to send, well, you can encrypt it or you can scramble it using a key, a secret key, which might be a physical machine like the Enigma 13 or it might be a number like 13.

如果你有没有加密的文本，你想要寄送的一些消息,你就可以加密它,或者你可以用一个密钥使其变得混乱，那就像一个英格玛的物理装置,或者他就是一个数字。

哈佛公开课 - 计算机科学课程节选

But the catch is that the party on the other end of things has to have that same machine or know that same number.

但是那个隐情是对立面的党派,必须有一个同样的机器或者知道那个密钥。

哈佛公开课 - 计算机科学课程节选