Disc copy protection system(how does it works?)

Even sector-
by-sector copying cannot bypass
this method since there is no
way for the copying software to
know where it might encounter
one of these duplicate sectors. In
order to create a working copy,
the disc must either be copied
raw using special hardware, or
be copied using software that is
designed to detect these
duplicate sectors, which is
extremely slow since it must try
to seek to every possible sector
from every single header
position.


DPM

A new method of protection
called Data Position Measurement
measures the physical position of
sectors on the disc and
compares them to a stored set of
values. Since mass-produced
game CDs are stamped (think
moulded disc surface instead of
burned) the positions are
identical for every disc. If you try
to copy the disc using any
method, the media you write to
will not match the original
positions. If you create a disc
image, the positions are (usually)
generated uniformly as to appear
normal, but they will not match
the original positions either.
More advanced copy protection
such as the newer versions of
SecuROM use DPM. Newer disc
image creation software such as
Alcohol 120% can duplicate
these measurements and put
them in the image file. Daemon
Tools allows you to emulate
RPMS, which fools DPM
algorithms into thinking it's the
original disc.


I hope this has been an
interesting read and that you
have learned something new
today

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