Pretty soon I think there will be a market for CCTV cameras that use a tamper-proof module to sign the video output, with a unique key and a key chain back to the manufacturer. Video evidence simply won't be admissible unless it's signed, and you can present the undamaged camera in court.
> Video evidence simply won't be admissible unless it's signed
Courts today readily admit the testimony of eye-witnesses, which ware notoriously fallible. It is a common misconception among tech people that all systems operate in rational ways, but this is only really the case for machines.
> It is a common misconception among tech people that all systems operate in rational ways, but this is only really the case for machines.
Very elegant and concise. I would say this extends to all deeply complex fields: engineering, physicists, quant, etc. They all have a mindset of "I can understand the whole system because they have logical components that build on top of one another" and so therefore expect and demand that all other fields do the same.
Eye-witnesses can at least be prosecuted for perjury if they're found to be deliberately lying. It's hard to apply the same threat to a CCTV camera.
Honest mistakes are obviously a separate issue, but the parallel there would be bad lighting or a corrupted recording, neither of which are new issues.
This is maybe one of the few relevant use cases of Blockchain technology: Cameras can add video checksums to a public audit log secured e.g. by proof of work or another trust mechanism. If enough parties archive this log it will be very difficult to forge videos without tampering with the actual recording device, because duplicates as well as tampered videos created at a later time would be easy to detect in the data, and the replication as well as proof of work would make it very difficult to forge the entire audit log.
You don't need a blockchain or proof of work for that, timestamped digital signatures are a thing that's being used already, you just need a proper trust infrastructure.
A blockchain with proof of work solves the problem of decentralization and absence of trust; however, for legal matters, having a centralized root of trust is the simpler way to go and requires much less resources.
However, tampering with the actual recording device is a very relevant risk - I struggle to imagine an attacker who has the desire and capability to make some serious crime, and convincingly fake a video as part of it, but would be foiled because they can't figure out a way to upload it properly in the exact manner as a real camera would.
In my understanding 50.1 % attacks are less of an issue here as they would be easy to spot since individual parties still have the old blockchain when the adversary publishes the new one, so by comparing them the forgery could always be reconstructed (if not averted).
As far as I understand this is a problem for Bitcoin because even temporary forging of the chain allows the adversary to double-spend funds, and once they are exchanged for real-world money/services they're gone. For an audit chain this shouldn't be a problem as it's only for logging and there is no monetary value tied to the chain. Also, the chain could be anchored with a traditional trust model and wouldn't need to be completely trustless like Bitcoin.
You cannot, but with the two forks you can see that someone tried to tamper with the signature of a given video as there will be conflicting signatures. That alone can make tampering unattractive for an adversary.
How so? What if all I want to do is cast doubt on a legitimate video? The point of the video manipulation is to manipulate the human response and casting doubt is just as effective. Moreso since the average person is not familiar with the technology & thus defaults to "eh - it's all fake" because there's no way they can distinguish the likely real from likely fake from "too hard to tell".
Yeah this is just another chain of evidence problem. We trust cops not to plant evidence, so long as they follow strict chain of evidence procedures. It’s an imperfect system but it’s largely effective.
The damage will really lie where it already does today, where people consume info without any filters in whatsapp groups within their bubbles. If they can believe a photoshopped image with a caption, they will be much more inclined to believe video "evidence", and no explaining of deep fakes will convince them otherwise.
Any tamper proofing process may be viable for news outlets and courts, but if the technology is easy enough to use there will be no escaping spreading of fabricated facts.
There will probably be an intermediary step: in the same way that one can try to find evidence that a picture was "photoshopped" or an audio recording was tampered with, there are probably hints (for experts) that a video was edited.
Commercial DVRs already sign video as its recorded and have for years.
It's more about chain of custody/location and time verification. Video authentication can't be used to tell if a video is real because it may just be a "real" recording of faked content. But you can say with some certainty that a video came from DVR X at Y time.
