Newbie with potential ECC protection

[psgama]

I solved it.

*SPOILER ALERT* FOR THOSE WHO WISH TO TAKE A CRACK AT IT.






I broke the equation down to the factors that made sense and worked out the patterns from there. In Excel if A2 contained the DevID the serial number would equal

*****SPOILER ALERT******
=((10000+(RIGHT(A2,1)+3)+((LEFT(RIGHT(A2,2),1)+7)*10)+((LEFT(RIGHT(A2,3),1)-3)*100))*857)+660

A complex problem broken down into patterns of numbers based on an input / output table of 10 original pairs. I'm feeling pretty darn good right now!

[chants]

In general we take a white-box approach to reverse engineering. You took much more of a black-box or grey-box approach and this seems to becoming a very popular method in the cryptography field. Software trace comparison, software fault injections, etc. But there is no one approach best suited for every sample you find out there. You have to study it and come up with the fastest attack plan route. Be it inductive or deductive strategies

[psgama]

I appreciate your comments.
My math is good but not great. This was fairly easy to solve, only maybe 12 total hours. Good challenge though.