Videoguard CAMs

easysat

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pj::
#1
I saw this on another forum where someone (presumably in the know) is talking about different versions of the Digibox:
"... the original PCB (A2/A3) used the ST20TP2 microprocessor, which itself is a dedicated processor for the reception of DVB MPEG-2, and they also used a dedicated conditional access chip call "ICAM" to decode Videoguard ... subsequent revisions (A4-A7) used a chip which integrated these functions in the ST20TP3"

What is interesting is that the writer says that early versions of the Digibox had a separate chip (integrated circuit) to do the Videoguard decoding. I had thought that this function had always been fully integrated into the ST Microelectronics decoder chip. I don't know which brand of Digibox has this separate chip (it must have been one of the first models on the market) but I am going to have a look at my old secondhand Amstrad DRX100's.

If this is true, it proves that it is easy to build a separate Videoguard decoder. Secondly it might be feasible for someone with enough technical knowledge to recover the "ICAM" chip and use it to build their own Videoguard CAM (which could then be used in any CI receiver). Thirdly it might not be so hot for the security of Videoguard to have boxes knocking around with an old, possibly less secure chip (especially if it is in the form of a programmable logic device rather than a custom chip).
 

easysat

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pj::
#2
I had a look in some old Amstrad DRX100s. The really old ones have the ST20TP2 channel decoder chip and a socketed chip marked "BSkyB". The newer ones have the ST20TP3 chip which has the Videoguard access module integrated (according to the ST Microelectronics website) and no chip marked "BSkyB".

This seems to confirm what the Sky insider said. The BSkyB chip must be the Videoguard descrambler. Curiously it is just a MACH215, a type of standard programmable logic chip made by AMD. (Although Lattice Logic has since taken over this part of AMD's business).

The other thing I noticed was a socketed chip from Integrated Silicon Solutions Inc which seems to be some sort of secure EEPROM memory. I wonder if this contains the serial number of the Digibox?
 

easysat

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pj::
#3
Someone who knows a lot more than me :+ says on uk.tech.tv.sky that the Videoguard ICAM descrambling chip in the early Digiboxes is in fact the Fujitsu MB87F2011. I checked in my Amstrad DRX100 and sure enough there is a big square chip with this code on. Apologies if I mislead anyone.
 
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da_judge

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#4
I just think maybe now we need 2 get our grubby hands on a full data sheet... unless you got 1... i be very interested... been to st web site... they not giving much away.. lol... anyway i let u know if i come up with anything and u like wise)(-)(
 
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#5
fairly new to this but why is there not a commercially available VG cam :confused

I was led to believe a while ago that the owners of VG would have to make the cams available to buy like Seca, Viaccess, Irdeto etc. It would certainly help the likes of me who use "standard" sat equipment. I have a spare slot just waiting for such a device :D

Cheers,

Shnigg
 

rolfw

Believe it when I see it Admin.
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#6
I think that they don't make one precisely because there are people like you, and me who have a little slot waiting for it. :) LOL
 
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da_judge

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#7
True.... I think it rude though... lol... it a good starting point though... im getting an old box 2 play with... only 4 educational purposes though... lets sit and wait
 

easysat

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pj::
#8
I saw elsewhere that the standalone ICAM chips can also be found in early Pace 2200's. You can buy a service manuals for the Pace Digiboxes complete with all the circuit diagrams. This should make it easier to study the signal flow.

On my Amstrad DRX100s, it's only the really old ones which have the ST20TP2 processor and ICAM chip. These ones also have the old version of the BSkyB logo on the front panel so that might help you identify a suitable box if you're buying at a car boot sale. Still the only way to be really sure is to look inside.
 
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