Hello,

I was wondering if anyone was familiar with any examples / literature of the purposeful insertion of errors into an audio / video stream as a form of DRM (digital rights management)?

If so, would you be able to provide me links to such examples / literature?

For example, let's say that rather than encrypt a video stream, we instead inserted visual artifacts into the video stream (or pops / clicks into an audio stream), thereby making the stream practically unwatchable (or audio unlistenable).

The purpose of doing this would be to ensure that if a user wanted to watch the video stream (or listen to the audio stream), that they'd need to do so using an "authorized" decoder / player.

The difference with this approach, compared to using a hardware decoder that merely decrypts encrypted video / audio packets using a decryption key (usually stored in hardware), is that it frees rights holders from having to worry about a decryption key being leaked to the public. Whereby a leaked decryption key may result in a complete breakdown of most, if not all DRM safeguards.

With inserted errors on the other hand, a would-be content "pirate" would need to reverse engineer the process / algorithm of fixing the purposefully inserted errors (assuming that the inserted errors aren't easy / trivial to fix), in order to properly watch the video stream (or listen to the audio stream).

The assumption is that reverse engineering a complicated video / audio repairing process / algorithm is more difficult / complicated than determining what an decryption key happens to be. That said, I'm in no way insinuating that it's easier to determine what an decryption key is via a brute force attack, but rather, through the use of more sophisticated methods (ex. system memory / core dump analysis).

Note: For this to work, we assume that we have some sort of safeguard against video / audio capture cards / software.

Any help / insight would be greatly appreciated.

Thank you,
Nelson

What you're describing sounds like the scheme cable TV used in the 80s to 'block' movie and porn channels. The (analog) waveform was 'distorted' (sync pulse messed with) in a way that caused TVs to not be able to show a good picture. It didn't work then and a digital version of it won't work now.

Oh, and you have the acronym wrong. DRM is Digital Restrictions Management, as it's not about rights but about preventing paying customers from using the content in an easy, convenient fashion. 

Anyone who has watched their TV flail helplessly flashing snow every 2 seconds instead of the movie you paid for due to that abmoniation called HDCP will know exactly what I mean.

Hello LamaBrew,

Thank you for the reply.

I assumed that this type of DRM had some serious limitations (especially back in the day), but thought that maybe nowadays things had gotten more sophisticated.

It looks like that's not the case (which is good to know).

Thank you,
Nelson

Nelson,

Pay TV is much more sophisticated now than back in the days of "scrambling" of analog video.  For that matter, analog video is almost non-existent now.  Digital video signals are protected by encryption, which is an important area of communications theory.

regards,

Neil