Relationship between 5 digit S/N and 4 digit code

[mcm151201]

Hello! I was hoping some folks out there could help me with a somewhat unusual relationship.

For use the Automotive industry there exists software for converting a 5 digit serial number to a 4 digit code, which is used by the car's computer. A number of people make this software, and I currently have it. However, I'd really like to find out what the relationship is between this serial number and the 4 digit code. I do not know how complicated the algorithm is-- that's where I was hoping to get some help! Below is a sample of inputs / outputs for examination. The number on the left is in the inputted serial number, and the number on the right is the 4 digit code. Any ideas?

11926 - 7482
51538 - 4369
85446 - 1589
43845 - 4576
81435 - 7615
91141 - 9777
51576 - 6277
73714 - 2561
85554 - 7278
19584 - 7070
87584 - 5246
35441 - 2016
71452 - 8254
02512 - 8158
67305 - 4815
67214 - 1748

Thanks!

 

[tkhunny]

How sure are you that it's neither copyrighted not proprietary? Now that you hae the software, did your EULA say anything about reverse engineering?

 

[mcm151201]

The reason I suspect it isn't is because multiple companies sell software which does the same thing. I should note that it looks like letters can be used in the serial number as well.

 

[JeffM]

I do not know the answer.

But if I was attacking this problem, I'd find out first what are the rules for generating serial numbers. Then I'd find out what the code is supposed to specify to the computer.

A 5-character alphanumeric serial number has over 10^25 possible values whereas a 4-character numeric code has exactly 10^4 possible values.

A car's computer, however, does not have to worry about whether it is supporting a Model-T. Nor does a computer in a Chevy have to worry about whether it is supporting a Toyota. Moreover, the computer may not need to worry about which 2008 Malibu it is supporting. Undoubtedly, most of the information in the serial number can be ignored for the purposes of the computer. If you knew what can be ignored in the serial number and what the rules were for specifying the characters that cannot be ignored, the reverse engineering MIGHT be pretty simple.