CD Copy Protection - Mode change....

Mateusz Matusiak

This is one of my ideas for a cd copy protection system.

We are going to create something like SafeDisc - but our sectors are not going to be weak The idea behind this protection is to change the Mode1 data organization to Mode2 Form1 + a small injection of data.... Those two modes are almoust the same...
They have 3 layers of error correction so the user will not notice any problems in using CDs with this data organization mode.

The diference that we will use is that the Mode2 Form1 data structure has a value = 2 in the Header, while Mode1 has 1. Let me explain

Each of the data organizations has a header. It looks something like that :

-------Header---------
| M | S | F | T |
------------------------

The header is placed after the Sync pattern... But its not important in this protection for us.
The first 3 bytes are the MSF (Minute , Second, Frame) and they are used to store the address of the sector. The last byte holds the type of the data organization. There are 3 values for this : 0 (not used), 1 : Mode1, 2 : Mode 2.

Now that we know the basics here is the idea :


Imagine that this is the data placed on CDR...

++++++++++++---------++++++++++++++++++++++++++

+ : are sectors in Mode2 Form1
- : are sectors in Mode1

Now please note that we don't have 3 tracks on the CD like someone could notice. We have one Mode2Form1 track with injected 5000 sectors that are Mode1. I created such CD using CDRDAO. Its a freeware cd writting software on GPL license(source included).

Now how does this preventd CloneCD/Alcohol from copying such CD.
Well, the answer is very simple. Our 5000 sectors that are in Mode1 will couse read errors if someone would try to read them (including Alcohol / CloneCD and other software..) becouse there are diferences in those two modes. The copying software will read the toc and see that on the CD there is only one data track in Mode2Form1. So he starts reading in this mode. When he will get into our gap of Mode1 injected sectors the drive will report it as read errors and the copy software will write there (to the image) a bad sector(s). Note: the bad sector will be reconstructed to Mode2Form1. Just the user data area will be filled with UUUUUUUUU...
So the header will be set to 2 while on our original CD we have 1 (in the gap area). After copying and burning the entire CD will have the header = 2 = A COPY !!!

Now the method has been described. Now how to check if the CD is copied or not. I have used a software named CDRECORD (also a GPL one) and found there a function ReadHeader. It did the work for me. I simply showed it what sectors to read (read the header) and it gave me back the results of the header.
But I think that it could be also arranged using a MMC command : ReadCD with some header reading flags -> www.t10.org - there you will find the specs of MMC-x Maybe there are also other ways to check for it... Who knows

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can u plzzz explain it in a easier way.....................plzzzzzzzzz