[AnthonyMouse]

The usual chain of custody goes something like: The store has a video surveillance system which the police collect the footage from, so the chain of custody goes through the store and the police which implies that nobody other than those two have tampered with it.

But then you have an inside job where the perpetrators work for the store and have doctored the footage before the police come to pick it up, or a corrupt cop who wants to convict someone without proving their case or is accepting bribes to convict the wrong person and now has easy access to forgeries. Chain of custody can't help you in either of these cases, and both of those things definitely happen in real life, so how do you determine when they happen or don't?

[iamacyborg]

Surely chain of custody applies if the accused has access to the evidence? Perhaps I’m missing your point or I’m overly optimistic about the legal system.

[AnthonyMouse]

Suppose the store manager is having a dispute with a kid who keeps skateboarding in the parking lot, so the store manager decides to commit insurance fraud by robbing the store herself and then submits forged video of the kid doing it to the police.

The store manager is in the chain of custody but isn't a suspect, the accused is the kid. The kid doesn't even know who actually committed the crime. How is the kid supposed to prove this?

[condiment]

In this case, chain of custody needs to extend to the capture device itself, and to any software that exists in the supply chain for the video content.

There are some experimental specifications that exist to provide attestation as to the authenticity of media. But most of what I’ve seen so far is a “perjury based” approach that just requires a human to say that something is authentic.

[_DeadFred_]

Chain of custody isn't real as long as the judiciary gives the government a 'good faith' pass when chain of custody isn't maintained/documentable in court. Go into Lexus Nexus and look up 'good faith' related to 'chain of custody'. Any 'protections' that can be waived away at the judges whim when the standard isn't met by the government are not actually real but pure theater to lend legitimacy to the American judicial system that it doesn't deserve.

[AnthonyMouse]

> In this case, chain of custody needs to extend to the capture device itself, and to any software that exists in the supply chain for the video content.

There are two major problems with this.

First, is all footage from existing surveillance systems going to be thrown out because it doesn't use this technology? Answer: No, because it would be impractical. But then nobody cares to adopt the technology because using it isn't required. How's that IPv6 transition going?

Second, that sort of thing doesn't actually work anyway. Surveillance cameras are made by the lowest bidder. Their security record is appalling. They're going to publish their private keys on github and expose buffer overflows to the public internet and leave a telnet server running on the camera that gives you a root shell with no password. Does it sound like hyperbole? Those are all things that have actually happened.

There is only one known way to prevent this from happening: Do not allow the hardware vendor to write the software. Any of the software. Instead, demand hardware documentation so that the firmware can be written by open source software people instead of lowest bidder hardware companies. This is incompatible with using the hardware vendor as the root of trust, which is a natural consequence because the hardware vendors are completely untrustworthy.

But let's suppose we find some way to do it. We'll pass a law imposing a $100 fine on any company that has a security vulnerability. Then there will never be a security vulnerability again because security vulnerabilities will be illegal; I'm assured this is how laws work. At that point the forger takes the camera and points it a a high resolution playback of the forgery, and the camera records and signs the forgery.

I kind of wish people would stop suggesting this. It's completely useless but it creates the false impression that it can be solved this way and then people stop trying to find a real solution.