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> But in the age of deep fakes, what does any of this actually prove? [...] a video deepfaked, etc. Can't you combine this with a basic public-key crypto schem
by qsort 6y ago
> But in the age of deep fakes, what does any of this actually prove? [...] a video deepfaked, etc.
Can't you combine this with a basic public-key crypto scheme if you're worried about fakes? You could extend the same scheme to multiple people if needed; obviously you can't prove a certain picture definitely wasn't faked, but in most cases a semantics like "X, Y, Z agree this is real" is sufficient.
- CGamesPlay 6y agoThe concern is first-party fakes, so I don't think public-key crypto helps anything. For example, in the "launching a cryptocurrency" case, you want everyone to believe you just launched the cryptocurrency, so that it's not possible for you to have done a bunch of advance work on hashing to create an unfair advantage for yourself.
- qsort 6y agoOf course my suggestion does nothing to solve the 'first party fake' problem, but that's kind of an unsolvable problem when taken in full generality, because it essentially amounts to 'how do you prove X is not lying". You don't; this is where reputation/trust comes into the equation.
- systoll 6y agoThe OP's problem of proving when a message is encoded is a tractable subset of 'prove X is not lying'. If you're not concerned about the actual author of a message faking its timestamp, you can just do public-key encryption, and write the date in the message.
- qsort 6y agoIf you combine public key crypto with parent's suggestion, you get a claim of the kind: "I can prove the timestamp is correct, and you'll have to trust me that the content is what I claim it to be", which is stronger than just doing public-key crypto. It's not a solution of the full problem, but it's something that should cover most common use cases, unless you have pretty weird requirements.