Iclass SE converting Serial Number into data that can be written on a blank fob

Hi Equiper. Thanks for the info.

I saw a guy scan the Iclass se fob, retrieve just the number (I believe SN), and then produce a working iclass se fob based on just the SN number (IE. 0607816ac0). I was trying to back-calculate it and come up with the data he used to create the new card… Does this sound familiar?