Making a program highly evolutive?

Is making any program highly evolutive impossible?

Think about a group of three people which are together and two of them want to be able to communicate in front of the other, but making sure that he won't understand anything. A private mutual key is needed to encode message, but if they share it, the third one will see it.

Everybody has one. Only higher beings knows them. They know keys are necessary, but if we knew it and get drunk, then somebody will have it and will know anything about we think.

I can tell that when you need something, is when you get more miserable.

The way of getting around the problem of the group of three is that the two of them get far away from the third, and share keys, but the problem is that the third one could get more interested in knowing what does that rare message means...

Even if a highly and ethernal evolutive program is possible, it will always have drawbacks. Nothing being 100% perfect. (For me) Perfection is an illusion, like selling bug as a feature.