Instead of using one single secret key, you could use a key pair. The tried-and-true symmetrical key would be replaced by a dynamic duo. One would be able to do the job of scrambling a plaintext message – performing the task in such a way that outsiders c

Instead of using one single secret key, you could use a key pair. The tried-and-true symmetrical key would be replaced by a dynamic duo. One would be able to do the job of scrambling a plaintext message – performing the task in such a way that outsiders couldn't read it – but a secret trapdoor would be built into the message. The other portion of the key pair was like a latch that could spring open that trapdoor and let its holder read the message. And here was the beauty of the scheme: yes, that second key – the one that flipped open the trapdoor – was of course something that had to be kept under wraps, safe form the prying hand of potential eavesdroppers. But its mate, the key that actually performed the encryption, didn't have to be a secret at all. In fact, you wouldn't want it to be secret. You'd be happy to see it distributed far and wide.