How Is SecuROM Physically Implemented?

Question

I'm reading various articles about this topic because I'm really curious on how SecuROM is implemented at physical level on optical supports, not at all a "How to crack SecuROM" question, just a "How is it made" one.

Source

A unique, uncopyable electronic keycode is added dur ing the glass mastering process

Source

At its core, SecuROM works by checking the density of data being read from a disk. Normally, data density of data accessed from a DVD would degrade from the inside of the DVD to the outside of the DVD, but SecuROM allows a vendor to add a specific pattern to the degradation of data density. If that pattern isn't found, then SecuROM will determine that the DVD is not valid and the game won't operate.

This is my research so far, but still I don't understand how something which is actually impressed on the optical support is uncopyable. If it can be read, it should be copied, unless it's some form of CD/DVD reader/burner wanted limitation in agreement with SecuROM producers.

If this data, or this data density, is read by a software, I suppose it is made of bits, and so bits could be rearranged in the copy, how can the system find the difference then?

In the end, how does SecuROM actually works in preventing the "secure part" to be copied to the destination support?

(Again, it's not for cracking purposes, nor for illegal uses, just curiosity)

Answer 1

After some deeper research I found out the only actual answer is: home burners are hardware limited to not copy certain data portions from optical supports. This way software houses are assured that their security systems will not be transfered on the copied disc, making them different from the original one.