4 ms·

How does that help? It’s like identifying in which continent a picture was taken.

by cm2187 4y ago

kortex 4y ago
Hardly. There's 7 continents (~3 bits of entropy), but dozens/hundreds of camera models this technique (6-8 bits). And it's hardly the only media forensic technique out there. There's ways of extracting the time of day without metadata, manipulation software chain, the lens used (sometimes down to make and model), and tons more. Before you know it, you've put a big dent in the ~33 bits needed to pinpoint a specific person.
semi-extrinsic 4y ago
I'm sure it will be useful for law enforcement or a defense attorney, if someone is on the record saying "I took this image with my Model Z camera" and they can prove that's a lie, it brings the rest of that persons testimony into doubt.
runlevel1 4y ago
I expect it's similar to knowing the make and model of a car that was used in a crime. Police aren't going to go around pulling over every one of those cars. However, if a suspect is captured, it can be a datapoint to help make the case.
- bad416f1f5a2 4y ago
  > However, if a suspect is captured, it can be a datapoint to help make the case. The paper talks about using this to go after people who are creating CSAM. That's a federal crime, which means an investigation will be conducted by federal agents. USAs have a 93% conviction rate – they'll case build like crazy to ensure they get a conviction. Any data point helps. Plus, they might ask you if you took a photo with your phone – say "no" and they prove you did, and you're also lying to the feds, which is a felony itself.
aeturnum 4y ago
There are no single perfect solutions. Being able to identify which continent a photo was taken in would often be useful. Geolocation, even inexact geolocation, is an essential part of intelligence work.
- cm2187 4y ago
  my point is that there are hundred of millions of users using the same iphone camera. That looks like a very minor datapoint to me.
  - anigbrowl 4y ago
    It's a point of correlation. Suppose you know person X in your area has a tattoo of a skull on their right arm, smokes Marlboro red cigarettes, is left-handed, and uses an iPhone, and all this information is fairly recent. You notice someone with a skull tattoo and decide to observe them, the three minor details take the id from a possible to a probable.
  - Ancapistani 4y ago
    True - but I might be the only person in my county using a Fuji X-Pro3.

How does that help? It’s like identifying in which continent a picture was taken.

by cm2187 4y ago

How does that help? It’s like identifying in which continent a picture was taken.

Hardly. There's 7 continents (~3 bits of entropy), but dozens/hundreds of camera models this technique (6-8 bits). And it's hardly the only media forensic technique out there. There's ways of extracting the time of day without metadata, manipulation software chain, the lens used (sometimes down to make and model), and tons more. Before you know it, you've put a big dent in the ~33 bits needed to pinpoint a specific person.

semi-extrinsic 4y ago

I'm sure it will be useful for law enforcement or a defense attorney, if someone is on the record saying "I took this image with my Model Z camera" and they can prove that's a lie, it brings the rest of that persons testimony into doubt.

runlevel1 4y ago

I expect it's similar to knowing the make and model of a car that was used in a crime. Police aren't going to go around pulling over every one of those cars. However, if a suspect is captured, it can be a datapoint to help make the case.

bad416f1f5a2 4y ago
> However, if a suspect is captured, it can be a datapoint to help make the case. The paper talks about using this to go after people who are creating CSAM. That's a federal crime, which means an investigation will be conducted by federal agents. USAs have a 93% conviction rate – they'll case build like crazy to ensure they get a conviction. Any data point helps. Plus, they might ask you if you took a photo with your phone – say "no" and they prove you did, and you're also lying to the feds, which is a felony itself.

aeturnum 4y ago

There are no single perfect solutions. Being able to identify which continent a photo was taken in would often be useful. Geolocation, even inexact geolocation, is an essential part of intelligence work.

cm2187 4y ago
my point is that there are hundred of millions of users using the same iphone camera. That looks like a very minor datapoint to me.
- anigbrowl 4y ago
  It's a point of correlation. Suppose you know person X in your area has a tattoo of a skull on their right arm, smokes Marlboro red cigarettes, is left-handed, and uses an iPhone, and all this information is fairly recent. You notice someone with a skull tattoo and decide to observe them, the three minor details take the id from a possible to a probable.
- Ancapistani 4y ago
  True - but I might be the only person in my county using a Fuji X-Pro3.