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Analogue Nagravision (Syster) encoder
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<blockquote data-quote="homercartman" data-source="post: 1078097" data-attributes="member: 414304"><p>Hi Captain Jack</p><p></p><p>Thanks for your reply.</p><p></p><p>Indeed I wanted to get some certainties regarding the mode bytes, whether it was a blind enum or a bitfield. And a bitfield it is.</p><p></p><p>This is what I noticed:</p><p></p><p>[CODE=clike]</p><p> //vbi[5] bits 0-1 choose encryption mode 1: d11, 2: nagra, 0:?, 3:?</p><p> //vbi[5] bit 2: unknown / untested</p><p> //vbi[5] bit 3 seems to say: if enc is nagravision, s,r are different ... Is it selecting another permutation table?</p><p> //vbi[5] bit 4: if 1, inverts audio at 12.8kHz, else ? KHz if 0</p><p> //vbi[5] bit 5: seems to ask for video decryption or not (unencrypted)</p><p> //vbi[5] bit 6: unknown / untested</p><p> //vbi[5] bit 7: unknown / untested</p><p> //vbi[5] bit 8: unknown / untested</p><p>[/CODE]</p><p></p><p>Regarding bit 3:</p><p>* with legacy permutation table, if enabled, then on my decoder, it seems part of the image is decrypted, part of the image is not. Some permutations are valid but not all. PAL color is globally restored, though.</p><p>* it doesn't look like a field-repeated "s,r" mode, where each field uses the same "s,r" list</p><p>* I tried to inject the French permutation table phase 2 in syster.c (the one that +/- kept the SECAM color line order, starting 1998), to see if it would work better with bit 3. No success.</p><p></p><p>So if bit 3 is a selection of permutation tables, my decoder seems not to be updated to table phase 2.</p><p>-> Was there another, pre-1998 French second permutation table?</p><p></p><p>Regarding bit 4:</p><p>-> Do you know what is the suppressed carrier frequency?</p><p>* It would be fun to see if the decoder is realtime responsive to this audio carrier bit. If so, this was maybe a possible countermeasure to defeat "dumb" unofficial descramblers that weren't looking at VBI anyway. In the mid 90's, I heard from somebody who was involved in its conception, that syster was highly prepared for countermeasures.</p><p></p><p>Regarding bits 0 and 1:</p><p>* If both set 0, it seems the decoder does something to the chroma. In PAL, red and blue burst<strong>s</strong> are more visible.</p><p>* I wonder if this decoder can also do other descrambling methods, such as cut and rotate with the "seemingly random" VBI fields. From the same source, 23 years ago, I was told it could.</p><p></p><p>By the way, I have several hours of tapes recorded with 1995-ish French C+ Nagra programmes, if this can help your investigations.</p><p></p><p>Clarifications:</p><ul> <li data-xf-list-type="ul">Was there another, pre-1998 French second permutation table? -> I mean: Assuming bit 3 selects which permutation table to use, besides the 2nd one used in France starting 1998, was there any other known secondary permutation table in syster decoders (Premiere, C+ Spain)?</li> <li data-xf-list-type="ul"> Would you like to get VBI dumps and if so, could you tell me how to proceed? -> I mean: If already available, a simple link describing the procedure and required hardware would suffice.</li> </ul><p>Thanks!</p></blockquote><p></p>
[QUOTE="homercartman, post: 1078097, member: 414304"] Hi Captain Jack Thanks for your reply. Indeed I wanted to get some certainties regarding the mode bytes, whether it was a blind enum or a bitfield. And a bitfield it is. This is what I noticed: [CODE=clike] //vbi[5] bits 0-1 choose encryption mode 1: d11, 2: nagra, 0:?, 3:? //vbi[5] bit 2: unknown / untested //vbi[5] bit 3 seems to say: if enc is nagravision, s,r are different ... Is it selecting another permutation table? //vbi[5] bit 4: if 1, inverts audio at 12.8kHz, else ? KHz if 0 //vbi[5] bit 5: seems to ask for video decryption or not (unencrypted) //vbi[5] bit 6: unknown / untested //vbi[5] bit 7: unknown / untested //vbi[5] bit 8: unknown / untested [/CODE] Regarding bit 3: * with legacy permutation table, if enabled, then on my decoder, it seems part of the image is decrypted, part of the image is not. Some permutations are valid but not all. PAL color is globally restored, though. * it doesn't look like a field-repeated "s,r" mode, where each field uses the same "s,r" list * I tried to inject the French permutation table phase 2 in syster.c (the one that +/- kept the SECAM color line order, starting 1998), to see if it would work better with bit 3. No success. So if bit 3 is a selection of permutation tables, my decoder seems not to be updated to table phase 2. -> Was there another, pre-1998 French second permutation table? Regarding bit 4: -> Do you know what is the suppressed carrier frequency? * It would be fun to see if the decoder is realtime responsive to this audio carrier bit. If so, this was maybe a possible countermeasure to defeat "dumb" unofficial descramblers that weren't looking at VBI anyway. In the mid 90's, I heard from somebody who was involved in its conception, that syster was highly prepared for countermeasures. Regarding bits 0 and 1: * If both set 0, it seems the decoder does something to the chroma. In PAL, red and blue burst[B]s[/B] are more visible. * I wonder if this decoder can also do other descrambling methods, such as cut and rotate with the "seemingly random" VBI fields. From the same source, 23 years ago, I was told it could. By the way, I have several hours of tapes recorded with 1995-ish French C+ Nagra programmes, if this can help your investigations. Clarifications: [LIST] [*]Was there another, pre-1998 French second permutation table? -> I mean: Assuming bit 3 selects which permutation table to use, besides the 2nd one used in France starting 1998, was there any other known secondary permutation table in syster decoders (Premiere, C+ Spain)? [*] Would you like to get VBI dumps and if so, could you tell me how to proceed? -> I mean: If already available, a simple link describing the procedure and required hardware would suffice. [/LIST] Thanks! [/QUOTE]
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