Dr. CASTRO: Then if it's positive, you add another couple of weeks for drug resistance testing, so you can see already a month interval easily going by before you have any result where you can hang your hat on.
By reading the encrypted data off of two cards and testing thousands of potential site codes against both cards until the decoded data displays a predictable interval between the two, he can find the site code and use it to create more card keys with a magnetizing device.