portion of the disc (a typical shortcoming of inexpensive CD drives). The MediaMax driver detects the
watermark if at least one mark cluster is present in the region read by the detector.
A sequence of 288 bits that we call the raw watermark is embedded into the 288 marked audio samples
of each mark cluster. A single bit of the raw watermark is embedded into an unmarked audio sample by
setting one of the three least significant bits to the new bit value (as shown in bold below) and then setting
the two other bits according to this table:
7
Original bits
Marked bits
0
0
0
1
1
1
111
011
101
110
111
111
111
110
011
101
110
110
110
111
101
011
101
100
101
110
101
100
011
100
100
100
110
101
011
011
001
010
100
011
011
010
010
001
010
100
010
011
001
001
001
000
100
010
001
000
000
000
000
100
010
001
The position of the embedded bit in each sample follows a fixed sequence for every mark cluster. Each of
the 288 bits is embedded in the first-, second-, or third-least-significant bit position of the sample according
to this sequence:
2,3,1,1,2,2,3,3,2,3,3,3,1,3,2,3,2,1,3,2,2,3,2,2,2,1,3,3,2,1,2,3,3,1,2,2,3,1,2,3,3,1,1,2,2,1,1,3,
3,1,2,3,1,2,3,3,1,3,3,2,1,1,2,3,2,2,3,3,3,1,1,3,1,2,1,2,3,3,2,2,3,2,1,2,2,1,3,1,3,2,1,1,2,1,1,1,
2,3,2,1,1,2,3,2,1,3,2,2,2,3,1,2,1,3,3,3,3,1,1,1,2,1,1,2,2,2,2,3,1,2,3,2,1,3,1,2,2,3,1,1,3,1,1,1,
1,2,2,3,2,3,2,3,2,1,2,3,1,3,1,3,3,3,1,1,2,1,1,2,1,3,3,2,3,3,2,2,1,1,1,2,2,1,3,3,3,3,3,1,3,1,1,3,
2,2,3,1,2,1,2,3,3,2,1,1,3,2,1,1,2,2,1,3,3,2,2,3,1,3,2,2,2,3,1,1,1,1,3,2,1,3,1,1,2,2,3,2,3,1,1,2,
1,3,2,3,3,1,1,3,2,1,3,1,2,2,3,1,1,3,2,1,2,2,2,1,3,3,1,2,3,3,3,1,2,2,3,1,2,3,1,1,3,2,2,1,3,2,1,3
The active protection software reads the raw watermark by reading the first, second, or third bit from
each sample according to the sequence above. It determines whether the resulting 288-bit sequence is a valid
watermark by checking certain properties of the sequence (represented below). It requires 96 positions in
the sequence to have a fixed value, either 0 or 1. Another 192 positions are divided into 32 groups of linked
values (denoted az and below). In each group, three positions share the same value and three share
the complement value. This allows the scheme to encode a 32-bit value (value A), though in the discs we
studied it appears to take a different random value in each mark cluster of each protected title. The final 32
bits of the raw watermark may have arbitrary values (denoted by below) and encode a second 32-bit value
(value B). MediaMax version 5 uses this value to distinguish between original discs and backup copies
burned through it proprietary player application.
0, a, b, c, d, e, 0, 0, f, 0, g, 0, h, 0, i, d, j, ¯
j, k, 0, l, m, 0, n, o, p, ¯
e, q, ¯
e, r, 0, ¯
p, s, d, ¯
m, t, u, v, w, t, ¯
l, a, x, c, u, 0, ¯
r, l,
f, ¯
d, v, 0, m, 0, ¯
q, 0, y, c, z, 0, j,¯i, ¯
g, , ¯
s, ¯
w, ¯
h, v, y, n, 0, 0, ¯
h, ¯
j, ¯
u, a, , 0, ¯
v, g, j, 0, 0, ¯
, ¯i, e, ¯
z, 0, r, , ¯
a, , ¯
d, ¯
z, 0, ¯
v,
, 0, x, s, ¯
g, ¯
r, 0, ¯
b, o, b, r, 0, y, ¯
, ¯
m, h, 0, ¯
a, n, ¯
f , ¯
t, 0, ¯
o, 0, ¯
, ¯, ¯
e, 0, 0, ¯
k, ¯
c, ¯
x, 0, ¯
f , p, z, ¯
x, i, 0, 0, , ¯
g, 0, 1, w, ¯
t, ¯
n, ¯
w,
i, 0, 0, ¯
j, m, x, , ¯
y, ¯
p, ¯
q, 0, 0, 0, e, ¯
, 0, 0, 1, g, 0, p, l, 0, ¯
, t, h, ¯
d, ¯, ¯
w, , ¯
, 0, ¯
p, q, ¯
f , 0, 1, , 0, ¯
c, , ¯
, ¯
s, ¯
b, ¯
, , 0, o,
0, q,¯i, 0, 0, ¯
, s, , ¯, ¯
h, 0, ¯
k, ¯
n, ¯
, , ¯
s, ¯
z, ¯
n, ¯
c, ¯
o, ¯
b, 0, ¯
t, 0, ¯
y, ¯
v, 0, , ¯
o, 0, ¯
, 0, u, , 0, ¯
y, k, ¯
u, z, ¯
, ¯
q, k, ¯
r, ¯
u, ¯
, ¯
, ¯
l, ¯
l,
w, ¯
k, ¯
a, 0, ¯
, 0, , ¯
m, b, f, 0, 0, ¯
x, , , 0, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
7
This design seems to be intended to lessen the audible distortion caused by setting one of the bits to the watermark value. The
change in the other two bits reduces the magnitude of the difference from the original audio sample, but it also introduces a highly
uneven distribution in the three least significant bits that makes the watermark easier to detect or remove.
11