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That just restricts the circle of people who can doctor these signed videos, it does nothing to solve the underlying issue. State actors would love to be able

That just restricts the circle of people who can doctor these signed videos, it does nothing to solve the underlying issue. State actors would love to be able to deepfake someone into a crime scene and then say 'hey look this is signed so it's totally legit'.

tartrate 7y ago
And since it's not much different than planting evidence we know for certain that it's going to happen.
swalsh 7y ago
Trust is a part of nearly every system. At some point you're just going to have to trust a person or company to get some value in a practical way.
- stult 7y ago
  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.
ThePhysicist 7y ago
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.
- PeterisP 7y ago
  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.
- joncrane 7y ago
  Can't state level actors take over 50.1% of the computing pool and achieve the same result?
  - ThePhysicist 7y ago
    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.
    - vlovich123 7y ago
      You can detect a 50.1% attack but how do you reconcile which fork is legit?
      - ThePhysicist 7y ago
        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.
        vlovich123 7y ago
        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".

tartrate 7y ago

And since it's not much different than planting evidence we know for certain that it's going to happen.

swalsh 7y ago

Trust is a part of nearly every system. At some point you're just going to have to trust a person or company to get some value in a practical way.

stult 7y ago
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.

ThePhysicist 7y ago

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.

PeterisP 7y ago
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.
joncrane 7y ago
Can't state level actors take over 50.1% of the computing pool and achieve the same result?
- ThePhysicist 7y ago
  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.
  - vlovich123 7y ago
    You can detect a 50.1% attack but how do you reconcile which fork is legit?
    - ThePhysicist 7y ago
      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.
      - vlovich123 7y ago
        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".