5 ms·

Why police (and media) cameras aren‘t forced to use camera hardware signing, aka content credentials, is beyond me.

by sveme 3mo ago

Iolaum 3mo ago
it's a feature, not a bug
AnthonyMouse 3mo ago
It's because they're a scam. Point the camera at a forged image with a higher resolution than the camera sensor and it will make a signed copy of the unsigned forgery. That's before getting into the practical problems with securing the keys. Every camera by every manufacturer has keys in it and the attacker only needs one key from one camera, and they get to choose the model? Creating something premised on needing to trust something with such a high probability of being compromised is worse than nothing, because it allows the ensuing forgeries a mechanism to pass themselves off as "signed" "real" images.
- sveme 3mo ago
  Really good points, thank you for pointing this out. What I'm mostly thinking of is the usage in e.g., social media. There will be efforts to do what you suggest, but for your typical facebook user and scammers, this might help with the more common situations where people use GenAI.
- gorgoiler 3mo ago
  But what about if: …the signature included the depth measured by the autofocus system across the image? …or a tiny stereo image was included to capture depth? …or a mini video in the ten seconds before and after the photo was taken? …and the key is in a tamper proof HSM? …and the key is deleted the moment the camera detects the case being taken apart? I know that it is a losing battle to try to build such hardware when offline attackers have essentially infinite time to dismantle even the most elaborate systems — no such thing as an un breakable safe, only how long it takes to break into it, etc — but I feel these are valid counter measures, are they not?
  - jappgar 3mo ago
    The more guarantees you put in place the more people believe the system is infallible and the more valuable the exploit becomes. If "signed" photos were treated as incontrovertible truth, then you'll just have people 3d printing hyper realistic masks or something.
  - AnthonyMouse 3mo ago
    > the signature included the depth measured by the autofocus system across the image? > or a tiny stereo image was included to capture depth? These systems work by having multiple sensors to use for depth perception, so enterprising hackers write software to create two images, one for each sensor, and put some kind of lens or mirror in front of the camera to direct a different image/screen to each sensor. The problem is fundamentally that the device is taking unsigned analog attacker-controlled input and then signing it, and is being mass produced. So whatever you're having it do, they put something that generates the same photon pattern in front of the device and you can't fix that with cryptography. You can probably make it so that a cheap camera needs a few hundred dollars in optical glass or similar, and expensive camera needs a few thousand dollars worth, but it's hard to see how you could make it infeasible to anyone with non-trivial resources and it's also easy to mess up even worse and make it practical even for anyone with a computer and a high resolution screen or two. > or a mini video in the ten seconds before and after the photo was taken? Which does what if nothing in the image is expected to be moving, or the thing you're pointing the camera at is a screen rather than a piece of paper? Also, now to verify the signature on your 50kB image you need a 2MB video? Then by default people won't distribute images that have the ability to be verified. > and the key is in a tamper proof HSM? Someone figures out a timing attack on the HSM or similar and now you can extract the keys from every device of that model. Happens over and over, the chances of every device getting this right are essentially zero. > and the key is deleted the moment the camera detects the case being taken apart? They get multiple cameras of the same model, take one apart to see how the detection works, then having figured out how it works, take the other one apart without triggering it. Or they extract the key without ever removing the case. Also, now your phone is going to delete its keys when you remove the case to replace the battery or a cracked screen etc., or if the detection system has a false positive? Then you need some way to transfer new keys to a thing that hasn't got any, which is an even worse attack vector than not deleting the keys to begin with.
notyourwork 3mo ago
The general population does not understand technology sufficiently well to set it up correctly, regulate it or use it correctly. Until we educate our population more on technology we will always be in this state.

Why police (and media) cameras aren‘t forced to use camera hardware signing, aka content credentials, is beyond me.

by sveme 3mo ago

Why police (and media) cameras aren‘t forced to use camera hardware signing, aka content credentials, is beyond me.

Iolaum 3mo ago

it's a feature, not a bug

AnthonyMouse 3mo ago

It's because they're a scam. Point the camera at a forged image with a higher resolution than the camera sensor and it will make a signed copy of the unsigned forgery. That's before getting into the practical problems with securing the keys. Every camera by every manufacturer has keys in it and the attacker only needs one key from one camera, and they get to choose the model? Creating something premised on needing to trust something with such a high probability of being compromised is worse than nothing, because it allows the ensuing forgeries a mechanism to pass themselves off as "signed" "real" images.

sveme 3mo ago
Really good points, thank you for pointing this out. What I'm mostly thinking of is the usage in e.g., social media. There will be efforts to do what you suggest, but for your typical facebook user and scammers, this might help with the more common situations where people use GenAI.
gorgoiler 3mo ago
But what about if: …the signature included the depth measured by the autofocus system across the image? …or a tiny stereo image was included to capture depth? …or a mini video in the ten seconds before and after the photo was taken? …and the key is in a tamper proof HSM? …and the key is deleted the moment the camera detects the case being taken apart? I know that it is a losing battle to try to build such hardware when offline attackers have essentially infinite time to dismantle even the most elaborate systems — no such thing as an un breakable safe, only how long it takes to break into it, etc — but I feel these are valid counter measures, are they not?
- jappgar 3mo ago
  The more guarantees you put in place the more people believe the system is infallible and the more valuable the exploit becomes. If "signed" photos were treated as incontrovertible truth, then you'll just have people 3d printing hyper realistic masks or something.
- AnthonyMouse 3mo ago
  > the signature included the depth measured by the autofocus system across the image? > or a tiny stereo image was included to capture depth? These systems work by having multiple sensors to use for depth perception, so enterprising hackers write software to create two images, one for each sensor, and put some kind of lens or mirror in front of the camera to direct a different image/screen to each sensor. The problem is fundamentally that the device is taking unsigned analog attacker-controlled input and then signing it, and is being mass produced. So whatever you're having it do, they put something that generates the same photon pattern in front of the device and you can't fix that with cryptography. You can probably make it so that a cheap camera needs a few hundred dollars in optical glass or similar, and expensive camera needs a few thousand dollars worth, but it's hard to see how you could make it infeasible to anyone with non-trivial resources and it's also easy to mess up even worse and make it practical even for anyone with a computer and a high resolution screen or two. > or a mini video in the ten seconds before and after the photo was taken? Which does what if nothing in the image is expected to be moving, or the thing you're pointing the camera at is a screen rather than a piece of paper? Also, now to verify the signature on your 50kB image you need a 2MB video? Then by default people won't distribute images that have the ability to be verified. > and the key is in a tamper proof HSM? Someone figures out a timing attack on the HSM or similar and now you can extract the keys from every device of that model. Happens over and over, the chances of every device getting this right are essentially zero. > and the key is deleted the moment the camera detects the case being taken apart? They get multiple cameras of the same model, take one apart to see how the detection works, then having figured out how it works, take the other one apart without triggering it. Or they extract the key without ever removing the case. Also, now your phone is going to delete its keys when you remove the case to replace the battery or a cracked screen etc., or if the detection system has a false positive? Then you need some way to transfer new keys to a thing that hasn't got any, which is an even worse attack vector than not deleting the keys to begin with.

notyourwork 3mo ago

The general population does not understand technology sufficiently well to set it up correctly, regulate it or use it correctly. Until we educate our population more on technology we will always be in this state.