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Discret 11, the French TV encryption of the 80s
- rwmj 6y agoThe system sounds similar to VideoCrypt. The French system delays lines. VideoCrypt worked by rotating each display line by a number derived from a PRNG. To decode the line the hardware had to buffer the line into a small piece of fast (for 1980s) RAM, and then using a number derived from the key would send the line to the TV starting at that offset and at the end wrapping around to the beginning. I know all this because in my first job we did a bit of experimentation to see if it would be possible to reconstruct the encrypted images without the key, and in fact it was quite easy because images are very highly correlated from one line to the next, so you just had to rotate each line through each of the 256 combinations and compare it to the previous line, and pick the one with the least difference. Although our system was far too slow to decode a live feed (this would be early 90s), and had some other problems. I didn't explain this very well - the Wikipedia page has a better explanation: https://en.wikipedia.org/wiki/VideoCrypt https://en.wikipedia.org/wiki/VideoCrypt
- mytailorisrich 6y agoIn general you don't even need to use the whole line to do the correlation. I remember writing a small program to decrypt image stills in the late 90s and it was surprisingly easy and straightforward, though obviously doing it in real time may have been another story...
- anthk 6y agoIn Spain we had Canal+ with Nagravision and you had either a combo of two software under Windows, or xawtv-nagra under Linux to decode it (ilegally OFC).
- Scoundreller 6y agoWas also used in N. America. It had many vulnerabilities in every card generation. You could program OEM cards, have man-in-the-middle devices, and full emulators. You Never needed to actually use the cards for Nagra. But The competitor DTV system built by NDS had an ASIC on the chip, so all solutions required a card at some level. But some setups could use one slave card for multiple receivers. Even over IP. Fun times!
- ttsda 6y agoThose cardsharing schemes still exist today, although they're being cracked down more and more.
- jaywalk 6y agoYeah, DirecTV's aggressive legal actions in the early 2000s drove that whole scene very deep underground.
- Scoundreller 6y agoIt’s a funny full circle. Instead of using OEM receivers and compromised cards, they’ve gone to running emulated receivers and regular full-sub cards.
- dillonmckay 6y agoDo you have more info on this? I used to be really into FTA satellite, but have not played with it in awhile.
- Scoundreller 6y agoNever really played with them hands on. Ubiquitous broadband and streaming services really nailed InternetKeySharing’s coffin.
- anthk 6y agoYes, with PICF84 microcontrollers.
- antman 6y agoIf you created a graph where the lines where the nodes and the difference between the lines where the edges then a traveling salesman algo might recreate it efficiently (or its vertical mirror I guess)
- eru 6y agoReducing a problem to the traveling salesmen usually doesn't go in the same sentence as efficiency.. It's almost the paradigmatic NP-hard problem. (And I don't understand how the reduction to traveling salesman problem would help here?)
- someguyorother 6y ago>(And I don't understand how the reduction to traveling salesman problem would help here?) Let the similarity between line i when rotated to position k and line i+1 when rotated to position j be d_k,j. Then you want to find a sequence of rotations r_1..r_n so that d_1,r_1,r_2 + d_2,r_2,r_3 + ... + d_(n-1),r_(n-1),r_n is minimized. In plain terms, you want to align each line so that it's most alike the previous line you rotated, but that in turn depends on the next-to-previous line you rotated, and so on up. This is a restricted type of traveling salesman problem: you want to visit all the nodes corresponding to each adjacent pair of rotation offsets so that the total edge cost (distance between the lines) is minimized. Since it's 1D, it should be pretty easy to solve with some dynamic programming (straightforward memoization). Calculate the minimal cost for each line down to k. Then for every possible choice of rotating the (k+1)th line, check which order of rotations of the preceding k lines that would minimize the objective down to the (k+1)th line, given that you rotated the k+1th line in that particular manner. Then determine the minima for every k+1 position and go on to line k+2. EDIT: It's even easier, since you can hold one line constant and rotate the next. Whenever you rotate the first line k, if you know the second line's optimal rotation for a zero rotation of the first line is j, you just rotate the second line k+j. So none of the above complexity is actually needed. I'll keep the comment to show how it could be considered a restricted TSP.
- eru 6y ago
- PoachedSausage 6y agoI see that has a reference to European Scrambling Systems 5 – The Black Book by John McCormac. I actually have a copy of that, it gives a rather entertaining overview of the arms race between the broadcasters and the hackers.
- NCG_Mike 6y agoI had it too ;-)
- mcbridematt 6y agoThe BBC ran a service called BBC Select in the early 90s with a VideoCrypt derivative, rather than line cut they shuffled blocks of lines around the screen - which worked better over more lossy and interference prone terrestrial transmissions. The technical paper from BBC R&D is quite interesting: http://downloads.bbc.co.uk/rd/pubs/reports/1995-11.pdf http://downloads.bbc.co.uk/rd/pubs/reports/1995-11.pdf There are a couple of captures of the scrambled transmission on Youtube - it's definitely far more advanced than the earlier Canal method https://youtu.be/HcCdw97_ESA https://youtu.be/HcCdw97_ESA
- raverbashing 6y agoAh I'm not sure there was fast (and cheap) enough RAM for that kinds of tricks in the 80's Most likely they would use a delay line https://en.wikipedia.org/wiki/Analog_delay_line https://en.wikipedia.org/wiki/Analog_delay_line Regular PAL (and I guess SECAM) TVs used one of those
- PoachedSausage 6y agoYou also had Bucket-Brigade devices. https://en.wikipedia.org/wiki/Bucket-brigade_device https://en.wikipedia.org/wiki/Bucket-brigade_device
- jimmaswell 6y agoSo essentially sleep sort in actual practice?
- 082349872349872 6y agoFrance also having been SECAM might explain why russian retro-80's concerts[1][2] often feature "Emmanuelle" (1974, NSFW) K7s in their "do you remember" interludes? [1] https://ru.wikipedia.org/wiki/Дискотека_80-х https://ru.wikipedia.org/wiki/Дискотека_80-х seems to be the main one, but it has competitors. [2] from the 90s, but if the instigators of the US PMRC had ever seen eurodance like https://en.wikipedia.org/wiki/E-Rotic https://en.wikipedia.org/wiki/E-Rotic they'd have been clutching their pearls. (the retro-encrypt screen's "pour en savoir+" mdr)
- hadrien01 6y agoFor the last few years they've put a low-bitrate channel on digital television that simulates the encryption: https://www.cpchardware.com/wp-content/uploads/2016/12/Canal.png https://www.cpchardware.com/wp-content/uploads/2016/12/Canal... It's not the real channel obviously (with digital TV the encrypted channels are simply blacked out), but it's a nice throwback.
- pnako 6y agoIIRC, aside maybe from some technical limitations, the reason it was not "proper" encryption where you can't make any sense of the signal is that it gave some idea of what was playing. The sound was completely scrambled but from the picture you could tell the program and tell if it was a football game, movie, talk show, etc. I had that channel for a while and watching WWE with French commentary was a favorite when I was a kid :)
- gregoriol 6y agoThe "make sense of what could be" might have been a good way to make people tempted to subscribe actually: it was so frustrating to identify a program you could be interested in and not be able to fully see it.
- Cthulhu_ 6y agoYeah, a weird kind of freemium model. I am assuming it wouldn't be hard to turn off the encryption for say an hour every once in a while and advertise a 'free viewing' every once in a while to get people to subscribe.
- dnpp123 6y agoThat's exactly what they did and where they got most of their customers from. Those 'free viewing' (canal+ en clair) probably had one of the biggest impact on french comedy TV culture ever. Some shows of that era are still on AFAIK.
- Totoradio 6y agoFor the football games, they turned on the encryption shortly after the game started. This created the expression "but en clair" ("unencrypted goal") where a team would score so early that the encryption was still off.
- PetitPrince 6y ago> biggest impact on french comedy TV culture ever. And french politics. French politics in the '90s and '00s wouldn't be the same without Les Guignols de l'Info.
- aivisol 6y ago> The audio stream is interleaved at the end of the blocks. If I remember correctly, audio was transmitted on a subcarrier some 6 or so MHz higher? Edit: Later in the article it is actually stated: "A normal SECAM signal uses FM on a 6Mhz carrier"
- FraKtus 6y agoThe sound just had the spectrum inverted. That's why when inverted it was sounding like crickets speaking. You could unscramble the sound just by multiplying it with the right sine wave at the right frequency. I remember prototyping that with a modular synthesizer :-)
- hyakosm 6y agoFrench SECAM was broadcasted in « L » (heritage from black & white 819 lines « E »), with positive image modulation and audio transmitted in AM. (https://fr.wikipedia.org/wiki/Norme_et_standard_de_t%C3%A9l%C3%A9vision#S%C3%89CAM_:_S%C3%A9quentiel_couleur_%C3%A0_m%C3%A9moire https://fr.wikipedia.org/wiki/Norme_et_standard_de_t%C3%A9l%...)
- philjohn 6y agoGrowing up in Belgium in the 80s and 90s I also remember Canal Plus and their encryption scheme - and trying (rather fruitlessly) to watch through a movie regardless - but of course, without the sound, that was a fool's errand. I always wondered how the decoding worked, and for its time, using the serial number of the equipment as part of this calculation was a good one. Also brings to mind the stories in the US of DirecTV pirating and how they put a stop to scores of pirates on Black Sunday - https://blog.codinghorror.com/revisiting-the-black-sunday-hack/ https://blog.codinghorror.com/revisiting-the-black-sunday-ha...
- anthk 6y ago> to watch through a movie regardless Ahem, yes, "movies".
- dnpp123 6y agoI guess that's the closest you can get of an 'insider joke' on HN.
- anthk 6y agoNah, Canal + in Europe was infamous because one kind of movies on Friday nights. You can guess which ones, male teens loved them. When BT848/878 PCI TV cards arrived, a few years later everyone tried to decode C+, for two (maybe three) reasons: - Movies. - Sports. - Often, music videoclips. The TV schedule quality of that channel was light years ahead compared to the ones you could watch in almost any European countries for free.
- dnpp123 6y agoTIL. I really thought it was only a French thing. Thanks.
- anthk 6y agoAt first, maybe. But they expanded really early in the 90's to the rest of Europe. Also it was something "for the middle-upper class". Not for a loaded guy, but for someone with some degree of freedom in order to spend your salary, such as a College guy/group living alone with no family. If you had a TV deco, for sure you have some elder brother/sister with a job or your parents were from a relatively good position. Everything changed in the middle-late 90's, OFC, as everyone began to buy multimedia PC's so kids at home could do their homework with word processors and the Encarta. Then the Avermedia TV arrived, cracking tools were widespread and with Linux and xawtv-nagra you had a really easy and secure way to watch a record C+ with no issues, except a huge 13GB file per hour, which you encoded into MPEG/XVID for convenience.
- ajuc 6y agoI think it was used in 90s in Poland by Canal+? At least when you tuned to the encrypted channel it looked exactly like it says in the article - every line was shifted randomly. I know people bought cheap pirated decoders that decrypted the channel without the need to pay the subscruption fee. It couldn't be the exact same system because we have PAL, but it was something very similar.
- terramex 6y agoPolish Canal+ used "Syster" encryption scheme. https://en.wikipedia.org/wiki/Nagravision#Analog_system https://en.wikipedia.org/wiki/Nagravision#Analog_system
- hyakosm 6y agoFrench transmitters were converted from Discret 11 to Nagravision/Syster between 1990 - 1995. First Syster decoders had retrocompatibility with Discret 11.
- praveen9920 6y agoI wonder how this would have worked in practice with lot of noise being added to signals. Is the noise too negligible to "delay" that is added?
- FraKtus 6y agoThe idea of the Radio Plans decoder is that the video black level was a little bit higher than the start of the signal after the horizontal pulse signal. Because of that, it was possible to detect if the delay was 0 1 or 2... Canal Plus reacted quickly by adding a little bit of noise to the signal after the horizontal pulse.
- pewu 6y agoAnalog encryption schemes are infinitely interesting to revisit today. The ingenuity of these folks trying to create an unbreakable encryption scheme with limited resources of 80's and 90's never ceases to amaze me. BTW A piece of software exists that can generate images encoded in various ways, that are supposed to be compatible with original hardware: http://cryptimage.vot.pl/cryptimage.php http://cryptimage.vot.pl/cryptimage.php I have yet to lay my hands on some decoder and try this out myself.
- danw1979 6y agoFabien Sanglard's blog is a true gem of the Internet. An excellent tech historian, in my humble opinion. If you're enjoying this, you might also enjoy Creatures Of Thought at https://technicshistory.com/ https://technicshistory.com/. Their history of the transistor series was superb reading.
- fred256 6y agoIn the Netherlands, I remember electronics stores carried DIY kits with names such as "TV signal quality enhancer". I only later realized what these were actually for.
- jimmaswell 6y agoI remember some weird little black box with a red button my parents had between the cable box and the wall coax. I wonder if that was it.
- themodelplumber 6y agoIt seems like three or four channels must have prompted at least some people to experiment with TV DXing. I wonder if that was very much a thing at the time.
- mpalfrey 6y agoPretty fascinating. CAS and broadcast tech is a pretty big interest of mine and I've been lucky enough to work for 2 of the biggest players in this space in the past (although not directly on the CAS side of things and sadly I'm not in the video space these days). Some very cool engineering was done without much in the way of technology being available!
- nickysielicki 6y agoThere's a lot of fun to be had today with broken OTA encryption on video content, if you have the land area to put up a C-Band satellite dish. [1]: https://www.lyngsat.com/hd/america.html https://www.lyngsat.com/hd/america.html [2]: http://colibri.bplaced.net/powervu.htm http://colibri.bplaced.net/powervu.htm
- dillonmckay 6y agoSo, what hardware is needed here, besides a C-band LNB?
- nickysielicki 6y agoA knock-off dreambox or a PCI dvb-s2 card is your best bet. Any cheapo DVB-S2 receiver will work, provided that you can get the raw MPEG-TS stream out of it and into a computer that can run oscam.
- jandrese 6y agoEnough space for a C-Band dish. They can get rather bulky.