Writing Program for Finding Answer key's

Here is an example.

There is Master Computer, It Looks At Your ID # and Answer Key , It lets you pass once they match with Master Computer's Internal Algorithm.


Your Answer Key given to you by looking at your ID#,


Master Computer Does not have database of ID#'s and Answer Keys
because any given time new ones can be created. So there is Algorithm.


I get hold of few ID# and Answer Key's and I Want to find what Algorithm they used creating the master formula.


For Example.

Machine 1 ID : 765567 - Answer Key : ACB6767BCA
Machine 2 ID : 324234 - Answer Key : DC1BHJ98BK

Both Answer Keys Created by looking at machine ID's
and by knowing many of them can i come up with Answer Key generator?
I want to be able to Enter Machine ID and I want to create Answer Key that matches Master Computer's Formula.
How many Machine ID's and Answer key's should i get hold of in order to figure what algorithm it uses?

It really depends on the algorithm they are using, read Hash Function on wikipedia, If maybe they are using an algorithm designed by themselves it could have a mathematical weakness, you will need as many Machine IDs and Answer Keys as you can, the more the better, and the apply cryptanalysis to find any relationship between the data, but if they are using a professional hash algorithm like SHA then there is nothing you can do to guess an Answer Key form a Machine ID.

it's really hard to discover the basic algorithm, if it's not a simple formula.
What you need to look for is called "regression analysis". I did some in the past, with mixed results.