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The question is way to vague for anyone to help you.
Are you writing a C program? Or a script? Or a paper?
Is this a new routing protocol you're designing? Or an existing one? Which one?
Are you routing IP packets? If not, then what?
By keys do you mean SSL keys? Or your own implementation of a key?
Do you mean four? Or is For an acronym?
We can probably help if you give enough information.