As in what technologies did they use and how did they logistically made it happen back then?
From what I could gather pay per view cable TV has been around since 60s – 70s. So for most of its existence it must have been using analog technologies right?
How did they deal with encryption and on-demand decryption then to allow for pay per view service to exist so earily?
I found out they must have used some kind of ‘scrambler’ as in some secondary device that was supposed to decrypt the signal from cable and feed it to the TV. But I assume scrambler was getting an analog signal right? so how did that analog encryption even work? And secondly, how did it even allow for on-demand decryption?
I mean, they couldn’t just – I don’t know – just tell me a password to unlock some encrypted channel could they? Were they mailing/selling some analog decrypting cards weeks before event or something?
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Each subscriber had a set top box. That set top box received EVERY channel that the cable company was capable of sending. However if a channel was a premium channel like HBO or a Pay-Per-view channel, that channel was scrambled. It was not like encryption, but a simple and yes, analog, scrambling of the video information. Often the audio channel was unscrambled. So us older folks who were teens back during the 80’s could tune into a movie on Cinemax even though we didnt pay for it. But it was *almost* unwatchable. But it would momentarily and randomly allow you to get a brief glimpse of some titties. If a subscriber called the cable company and asked for a Pay-Per-View event like a boxing match, the billing system would send batches of these analog token requests out on their cable networks. The set top box had an identification code like a serial number in its electronics. If that code matched up with a permitted list then that channel would now have the key to unscramble the channel, not because the subscriber had a different analog transmission, but because the set top box had the code to unlock that scrambled transmission. After a Pay-Per-View event a code would be sent out from the cable company to re-scramble that particular channel.
>I found out they must have used some kind of ‘scrambler’ as in some secondary device that was supposed to decrypt the signal from cable and feed it to the TV. But I assume scrambler was getting an analog signal right? so how did that analog encryption even work?
Like the name implies, it was not really an encryption, but signal scrambling. Which means, the signal that you got from your TV line was just somehow altered (e.g. frequencies/phases of the signal shifted) such that displaying it on a TV directly was not possible anymore. Such scrambling is of course not very secure and often possible to reverse engineer in contrast to modern digital encryption.
> And secondly, how did it even allow for on-demand decryption? I mean, they couldn’t just – I don’t know – just tell me a password to unlock some encrypted channel could they? Were they mailing/selling some analog decrypting cards weeks before event or something?
Yes, this is one possible way. The technique how the signal was scrambled could be changed for each TV event and they would send out descrambler cards for that exact event via mail.
More sophisticated descramblers later in time could also be activated/deactivated remotely via the TV signal (they would send digital, encrypted commands for this in addition to the analog, scrambled TV signal)
Analog-only cable television systems relied on set-top boxes to control access to programming
Everything has been converted to digital and your cable provider can turn it on and off with a click.
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Seeing some good discussion around the old analog scrambling tech. You also had filters that would be placed on your cable connection that would filter out analog channels that you didn’t have access too, Such as premium channels or packages. (I remember the huge lift auditing and removing all those old filters when systems went 100% digital around a decade ago)
With digital cable, which came into play during the late 90’s and early 2000’s, things got a lot more interesting, and interactive. There were 2 major players in the digital cable space (in the US at least), and they did things a little differently, but at a high level the concepts where the same. I’m most familiar with the backend on the SciAtl systems, so most of this will reference their approach.
With Digital cable systems, The video signals were now digitally encrypted. The SetTop boxes were also able to speak “digital, and you ended up with 2 way communication in many cable systems. Some systems utilized a phone line to call out for the return path, but often there was a frequency that the boxes could talk back on. For communication from the cable system to the box, you also now had a dedicated “out of band” downstream communication path. The meant that you could receive information from the cable system without needing to be actively tuned to a specific channel (in-band), and that this OoB downstream path could send a lot of data down to the boxes.
Your cable system would often be broken up into chunks, similar to how the nodes for cable internet are done, and the return path would be broken up into even smaller groupings. This helped to ensure that the limited bandwidth wasn’t overwhelmed with too many clients.
The cable boxes were addressable. In the SA systems, they actually got assigned an IP address by the controller when it signed in (sorta like dhcp, but not). The boxes also used a sort of public/private key for encryption and identification. IOW’s, the box’s info had to be loaded into the controller so it knew how to talk to the box and could give it the decryption instructions for services.
Among the data sent out of band to the cable box (along with the guide data), was information on the pay per view events. This included an event ID, the times for the event, and the costs. It also included information like the buy window to specify when you were allowed to purchase the event.
You could do the traditional “call to buy the event”, which would have the cable rep authorize your account for the event, which would the. Be sent to the box to tell it it was authorized to tune to and decrypt the Ppv event.
But you could also now just buy it from your box. When you did this the box would basically store the event purchased and deduct the cost from its internal available credit. Then every so often the controller would poll the boxes and ask for all the Ppv purchases made since the last poll. It would then confirm the data sent, and authorize the box to clear the purchase and reset the internal available credits to purchase events.
What the internal credit counter did, was it prevented someone from making hundreds of dollars in PPV purchases without sending it upstream to the billing system, which may or may not allow that large of purchases on an account depending on their credit policies. It also prevented someone from placing a return filter on their side that prevented the box from reporting the Purchaed PPV events, So they could buy all the Ppv they wanted without the box ever being able to report those purchases to the billing system.
One thing the interactive vs call in purchase also allowed was for the differences in event pricing. Interactive was generally only authorized on residential accounts, while bars/clubs/etc could purchase Ppv events by calling in to buy them. That is in large part because often PPV events were a LOT more expensive for a bar or public location to purchase than a home, due to the event promoters figuring homes had a few eyeballs, while public venues could have dozens/hundreds, and charge accordingly.
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