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8.1 Locking features
There are
three
types of lock
functions:
disable CD-DA
disks,
one publisher only (levell) and confidential
(level2).
The
important things
here are the "Key Disk". These disks are only
supplied by Philips and
have
a
unique
code embedded for each
customer.
8.2 Lock functions
In
normal circumstances
-without
protection- an application on
disk
has
the
same name as
it's
enty in
the
File Structure Volume
Descriptor (FSVD). When starting a CD-i
application,
the file
name
and directory path of the application
is
read from the
FSVD,
the
file
loads into
memory and the
first module in the file
starts executing.
The protection mechanism consists
in
allowing a difference
between the FSVD and the applications' file name. A disk
especially mastered for
level
2 protection contains two
applications
:
one application with a standard
name
and one
application with a postfix added
to
the same standard name. A
normal player will read the standard filename
in the
FSVD and
play the
'standard'
application. Only a player able to filter out
the difference between both names will play the application
with the adapted application. The standard application on the
disk will thus play on all
players,
except on the player the disk
is
locked
to (when
locking
is enabled). This application could
be used to
inform
the user that the disk he
just inserted
is
intended
for someone else
eyes.
The difference between both
names is created
by
adding a postfix to
the
normal name:
Adapted name=
"FSVD
name"
&
"company dependent part"
&
"variable
code"
A protected
file
name on disk with
'cdi_show'
as FSVD-entry
would become:
Adapted name=
"cdi_show"
&
&
"_LCK"
"0001",
resulting
in
'cdi_show_LCK000l
'
as filename on disk.
The variable code
in the
adapted file name can be
used in
many
different ways: as
identification
number of
the
application,
as
chapter
number
when
the
total package has one application per
chapter,
as security level,
...
The player holds the 'company
depentent part'
together
with a
list
of four digit numbers
(equivalent to the adapted application
names
on disk) and only
plays the disk that
have
a number from this
list in
their adapted
application name. This content of the
list
depends of the
applications
the
player may or may
not
run. The confidential
application will not play when it's name does not match one of
the
entry's
in
the list.
An example:
The company Bigdeal distributed the product
information
to
their
dealers on
CD-i disks
(mastered with TCM
in
mind). The
complete set, divided over several
disks,
consists of a
documentation
part,
a sales
training,
technical
instruction,
etcetera. Bigdeal also ordered a keydisk with PROl as company
dependent part.
The player
of the sales people was
locked to
the sales
training
and wouldn't play any of
the
disks they
received except
the
sales disk. Because the sales people are
humans too, they
inserted
the
technical
disk
in
their player. The
player responded
this
action with a message on the screen: "The
technical application will
not
run on this player". Suppose the
adapted name of the sales application was
'salesPRO10004',
8. KEYDISC FUNCTIONS
then the entry in the postfix
file
would be '0004'. The player of
the technical staff may access the documentation (with
docPRO10002 as name) and the technical disk (with
techPRO10007 as name). The contents of the postfix file
in
their
player would be
'0002'
and '0007'.
8.3 Secondary locking function
Unfortunately,
the locking
features
just described
are only
applicable to CD-i disks
.
In some cases the
locking features
can't be implemented on a
CD-i title
due to limitations in
the
pre-mastering step
.
The
locking
method can
not
be
implemented on Video CD's or Photo-CD's.
To
overcome this
drawback,
a secondary protection mechanism (level
1) is
implemented in
the player.
The mechanism is similar
to
the previous described system but
uses
other data
to
check
permissions.
When
locking is
enabled
and
there
is a postfix
file in
memory
-with
at
least
one
entry-
the inserted disk is searched for adapted
filenames.
In case no
names are
found,
the player checks the four first characters of
the 'Publishers
string'
in the
FSVD on disk. When they match
with the code in
the
postfix
file,
the disk will play.
Else,
the
disk
is
ejected and the customer specific message appears on the
screen.
The major difference between both locking systems is that the
level
1 protection connects the disk(s) to a particularly player
while the
level
2 protection
locks
the player to a particularly
disk. In the first case the disk(s) will not play on other players
and the player won't play other disks
.
In the second
case,
the
locked
player will only play the protected disks, with the major
difference
that
these disks can play on any other player.
8.4 CD-DA lockout
The CD-DA disable function is rather straight forward: when
keydisk locking is
enabled,
the player refuses to play audio
disks.
The following table gives an overview of the different disk-
player combinations possible:
Normal player
CD-i in
locked
mode
Normal disk
CD-DA disk
One publisher only
(level
1)
Confidential disk
(level 2)
Will play
Will play
Will play
Will not play
/
play different
(*)
if
lock
strings are matching
8.5 Other key disks functions
Depending on the customers needs
:
-
Option access protection.
- Start-up messages.
-
Pointing device start-up (see also 3.2.4).
NOTE
Will not play
Will not play
Will play
( *)
Will play
(*)
- The
Load
System Modules (see also 5.4) feature enables a
great variety of custom developped
features/
drivers.
21
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