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Isn't the point to prove physical access to the camera. As in, this stream originated at this TPM which was sold as part of this camera. So, the best you get i

Isn't the point to prove physical access to the camera. As in, this stream originated at this TPM which was sold as part of this camera. So, the best you get is that the stream shows it wasn't produced with access to a particular camera. Then impersonating a YouTuber, say, requires access to their physical camera.

jacquesm 4y ago
> Isn't the point to prove physical access to the camera. Yes. But since you can't really prove who had and who did not have physical access to the camera (what are you going to use, video evidence ;) ) that carries little weight. Let's say we're talking about a death penalty or a multi billion $ lawsuit, the stakes would be so high that to rely on something as trivial as a signature on a video stream would be way too risky because of the consequences. Which expert would sign on the dotted line to the statement that 'the equipment has not been accessed by someone who wasn't authorized to do so'? And that's before we get into the question of whether this camera really is the only way that this particular video could be generated (can duplicates of the TPM be made by the manufacturer?), you'd have to do a lot of work to make guarantees that would stand the test of time. All it takes is one 'DVD Jon' and you can kiss your carefully constructed scheme goodbye. Finally, the whole chain of that video would have to preserve the signatures, which in a world that tries to balance privacy with other concerns may not be feasible and in fact could well have downsides all its own. Personally I would much rather see the level of skepticism against all kinds of digital evidence go up than to see the trust go up due to supposedly magic signatures and other tricks to pretend that we have a perfect lock on this stuff. Every time we believe we do someone comes along that proves us wrong, usually after the damage is done. See also: fingerprints, face recognition, DNA evidence, lie detectors, bomb detectors and so on.
- alach11 4y ago
  > Which expert would sign on the dotted line to the statement that 'the equipment has not been accessed by someone who wasn't authorized to do so'? You have a lot more trust in the ethics of expert witnesses than I do.
  - jacquesm 4y ago
    Well, expert witnesses that give false testimony are a lot more rare than expert witnesses that are going to go on the record for things that they know to be false. Expert witnesses and liability are a very interesting area of the legal system. There are all kinds of variations on this theme ranging from blanket immunity to various forms of liability. Knowingly giving false testimony would likely lead to problems, especially if say a panel of experts would in turn testify that said expert should have known and could have known that what they testified was wrong. I'm not aware of a case that went that far, but I would love to read more about such conflicts between expert witnesses on two sides of a lawsuit, usually the experts agree in broad terms on their testimony, and may differ in the details. Maybe some who have served in such a capacity can chime in here?
- pbhjpbhj 4y ago
  TPM is supposed to be a secure enclave that's resistant to electronic access, so non-duplicable (in theory). So as much as anything, you're pricing access by the signing of a file with the TPM. That means continuity of 'proof' -- perhaps we'll get to the point where famous people perpetually film themselves using a third-part verifiable module to sign the data, just so they can show "that wasn't me" (ie technological deniability). I don't think you can show the reverse (it was you), nor can you make a 'proof' without an established chain (you're only proving that you verified something with the same equipment you previously used). Reputation seems like it could become much more a part of social media, like, this video was signed by all these witnesses to endorse it as a true account.
Workaccount2 4y ago
Just like this post about making a software bypass to a security check, there are hardware guys making bypasses to security checks. Now you create a situation where hardware bypassed cameras have immense value to bad actors.

jacquesm 4y ago

> Isn't the point to prove physical access to the camera. Yes. But since you can't really prove who had and who did not have physical access to the camera (what are you going to use, video evidence ;) ) that carries little weight. Let's say we're talking about a death penalty or a multi billion $ lawsuit, the stakes would be so high that to rely on something as trivial as a signature on a video stream would be way too risky because of the consequences. Which expert would sign on the dotted line to the statement that 'the equipment has not been accessed by someone who wasn't authorized to do so'? And that's before we get into the question of whether this camera really is the only way that this particular video could be generated (can duplicates of the TPM be made by the manufacturer?), you'd have to do a lot of work to make guarantees that would stand the test of time. All it takes is one 'DVD Jon' and you can kiss your carefully constructed scheme goodbye. Finally, the whole chain of that video would have to preserve the signatures, which in a world that tries to balance privacy with other concerns may not be feasible and in fact could well have downsides all its own. Personally I would much rather see the level of skepticism against all kinds of digital evidence go up than to see the trust go up due to supposedly magic signatures and other tricks to pretend that we have a perfect lock on this stuff. Every time we believe we do someone comes along that proves us wrong, usually after the damage is done. See also: fingerprints, face recognition, DNA evidence, lie detectors, bomb detectors and so on.

alach11 4y ago
> Which expert would sign on the dotted line to the statement that 'the equipment has not been accessed by someone who wasn't authorized to do so'? You have a lot more trust in the ethics of expert witnesses than I do.
- jacquesm 4y ago
  Well, expert witnesses that give false testimony are a lot more rare than expert witnesses that are going to go on the record for things that they know to be false. Expert witnesses and liability are a very interesting area of the legal system. There are all kinds of variations on this theme ranging from blanket immunity to various forms of liability. Knowingly giving false testimony would likely lead to problems, especially if say a panel of experts would in turn testify that said expert should have known and could have known that what they testified was wrong. I'm not aware of a case that went that far, but I would love to read more about such conflicts between expert witnesses on two sides of a lawsuit, usually the experts agree in broad terms on their testimony, and may differ in the details. Maybe some who have served in such a capacity can chime in here?
pbhjpbhj 4y ago
TPM is supposed to be a secure enclave that's resistant to electronic access, so non-duplicable (in theory). So as much as anything, you're pricing access by the signing of a file with the TPM. That means continuity of 'proof' -- perhaps we'll get to the point where famous people perpetually film themselves using a third-part verifiable module to sign the data, just so they can show "that wasn't me" (ie technological deniability). I don't think you can show the reverse (it was you), nor can you make a 'proof' without an established chain (you're only proving that you verified something with the same equipment you previously used). Reputation seems like it could become much more a part of social media, like, this video was signed by all these witnesses to endorse it as a true account.

Workaccount2 4y ago

Just like this post about making a software bypass to a security check, there are hardware guys making bypasses to security checks. Now you create a situation where hardware bypassed cameras have immense value to bad actors.