a device that can encrypt what you type character after character
Um, I fear that such a device's "encryption" will only create permutations (mix up) of the actual printable characters. And I am not convinced it will work properly with unexpectedly large character sets.
Also, if the hacker expects an user types mostly in a certain language, it won't be too difficult to find the key based on what characters come out most often.
a few different people tried to explained why it won't work for different reasons but OP doesn't understand any of the answers. He is obviously not a developer, and doesn't have a technical background. This is just a wild imagination.
I hope that my explanation is simpler
And yeah, it won't work, not like that.