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Of 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
by qsort 6y ago
Of 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.