I am writing a system, for which I need to generate unique transaction numbers (which can be verified by myself). I want to use something similar to that used by credit cards, where a string of the form:
I want to be able to craft an algorithm that generates only a subset of the range of keys possible from the set of all possible combinations of keys above.
I don't know much about security, but I'm guessing that the solution would probably involve coming up with a logic procedure that restricts the generated set, such that members of the 'valid' set, satisfy a CRC check.
I would be grateful if anyone could shed more light on how to implement this.