TUCoPS :: TV, Cable, Satellite :: ham024.txt

HBO descr4mbling

    As many of you know on January 15, 1986 HBO began scrambling the signal 
it transmits via satellite to cable companies for local distribution. What 
this did was effectively keep all dish owners from stealing HBO signals, 
since then several other cable programmers have begun to follow suit.
    What HBO came up with is an encryption system called Videocipher II. It
was developed by M/A-COM, an electronics company in Burlington, Mass. What
this device does is it distorts the video and converts audio signals into
digital information and then scrambles these numbers so they can be de-
crypted only with a special descrambler.
    HBO's digitized information is en-crypted using the data encryption 
standard(DES), which was developed to protect unclassified government info.
With DES, once the signal is digitized, it's translated into an scrambled
signal called cipher. The form of the cipher is determined by an algori
 up a digitized signal and a key, a 56 digit string of 1's and 0's
that work like a password.
    This password directs the algorithm. The password is what makes the 
scrambling unique. Even if someone could figure out the algorithm, he cant
do shit without the password. And HBO says it is very unlikely that someone
ever will since there are over 72 quadrillion possible passwords.
    The hard part of HBO's system is not in the scrambling, but its in the
descrambling. First HBO sends a unique signal via satellite to every local
cable operator's or subscribers descrambling box(used with dishes). Then 
each of these descrablers deciphers its signal with its unique password. In
other words, a descrambler can only recieve a message sent specially to it.
But even when this message has been de-crypted, a clear transmission of HBO
does not come through because the message is not the program itself. Instead
the message tells the descrambling unit which cable services it's allowed
d gives the unit another password called the monthly key.
    Like the first password, the new key is a 56 digit series of 1's & 0's.
But unlike it, the monthly key is the same for ALL cable operators and, as
its name implies, it is changed every month. This way a descrambling unit
with an out-dated monthly key wont be able to descramble any more info sent
by HBO. However if the descrambler has the right key, it receives yet another
message from HBO, which contains information about the program being shown
at that moment.
    Before the program comes on, one more major decryption must take place.
And before that can be done, the descrambling unit must determine whether or
not the customer is supposed to receive whatever HBO is sending at that time
If he is, then his descrambling unit gets the program password, a key that
changes every hour! This password descrambles the last code that HBO sends,
and the program comes in clear.
    So as you can see it is a very complex op
put it this way,
if you had access to a mainframe and test every combonation(72 quadrillion)
you might be able to get the right combo once every 10,000 years, but un-
fortunately the program code changes every hour. And even if you did happen
to get lucky and get it on the first try, you will still have to try and
get the next program code in an hour..
    Another way you could try is to get the unique descrambler key for a 
certain box, but that 'supposedly' is impossible because the chip with the
descrambler key on it is designed so that the information on it cannot be
This information was provided by: The Infiltrator of 305.
                                       AMPHRAS & Co.


TUCoPS is optimized to look best in Firefox® on a widescreen monitor (1440x900 or better).
Site design & layout copyright © 1986-2024 AOH