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hold on witj the algo

S

scoodidi

Guest
#1
Read on a french forum
Read This!!!!!!!!!!
January 25 2001 at 6:11 PM pripps2


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Viaccess algo - a donation from the Russian Maffia
Viaccess is a modification of Eurocrypt M. In this mod the key has 8
bytes
when EC-M has only 7.
If the 8th byte is zero then Viaccess works exactly like EC-M.

If the 8th byte is nonzero then this will trigger several different
small
mods. One of these mods is in DES routine. 7 key bytes are used in des
but
the 8th byte is used in special core function in every DES round. This
mod
is done just before expansion E and it alters the 5th data byte which
is
the first of the right-hand 4 data bytes to be used in the DES-round.
Therefore it has affect in S-boxes 1,2,3 and 8. The mod is done only
with
this byte for expansion E and the original byte remains the same.

In this mod the 8th key byte is multiplied with the data byte for at
get
a 16 bit word. Then the data byte is added to this word (upper 8 bit
byte
is incremented if there was a carry with the lower byte). Then the 8th
key byte is added to the word on the same way. Then the upper byte is
subtracted from the lower byte. If there was a carry in this subtract
then result is incremented by 1. Then this result byte is used instead
of the original byte in expansion E.

All hash algorithms are working like in EC-M when this DES
modification
is done.

CA 88 and CA 18 message processing:

If the 8th keybyte is nonzero then first 7 keybytes are rotated left
by 2 bytes.

This means key(k1 k2 k3 k4 k5 k6 k7 k -> key(k3 k4 k5 k6 k7 k1 k2
k

If the 8th key byte is even then this is the last modification but
if it is odd then there is still one very complicated data
modification.

First there is one constant which is 5Ah if the 8th key byte is odd
and
less than 10h. If the 8th byte is odd and bigger than 10h then this
constant is A5h.

In the data modification is used hash result for the 8 bytes which are
just before the encrypted data. If there are not enough bytes in these
hash results then values 00 are used in missing bytes. These hash
bytes
are first ANDed with the constant and then XORed with the encrypted
data bytes. Result bytes are then used as input data for DES. Ofcourse
DES is done with necessary mods. After DES the result bytes are ready
for
CA C0 message or other use in CA 18 messages.

Now we can implement this in the actual emu files
The next version of ViaXeniX will include it
 

jimmi

Regular Member
Messages
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Likes
0
My Location
pj::
#2
thanks scoodidi

can you post the french fourum's link

i got a good one

http://now.at/lotfinet


cheers
------
jimmi
 
S

scoodidi

Guest
#3
here the link its the french most activ on digital tv
http://pub7.ezboard.com/bseca40544