Comment by NoImmatureAdHom | Hacker News Reader

Comment by NoImmatureAdHom | Hacker News Reader

NoImmatureAdHom

If you want to prove provenance without centralization of power like certificate authorities, you could do it with a blockchain. I'm sure someone has implemented this.

Alice wants to prove to everyone that she took a photo. Or, at least, she wants to attest that it is hers from a given time on.

1) Alice takes photo at t=0

2) Hash is calculated of photo

3) Hash is signed with Alice's private key

4) Signed hash is uploaded to Ethereum blockchain (probably bundled with thousands of others to save money, or on some other cheaper/faster blockchain)

5) Bob can verify that Alice had this photo starting at t=0

Combined with other information (like "This is a photo of events that happened on Tuesday starting around 11AM"), this could be useful in the context of journalism or whatever's replacing it on the web.

It doesn't help with determining how Alice took the photo - with her camera or with her version of Stable Diffusion. Only that at t=0 Alice uploaded the hash of the photo she had before it.

Exactly.

What your parent described is a type of trusted timestamping and one doesn't need blockchain to implement it.

[0]: https://en.wikipedia.org/wiki/Trusted_timestamping

Thanks--I didn't know the generic term.

Yep, true. I can imagine cases where it is relevant, though. Like...something happens in the past, and people only become interested in it at some point in the future.

For instance, Alice is accused of a crime that happened a month ago. There exists photo / video of Alice that is attested this way proving she hasn't committed the crime, and this is taken by Bob who seems to be an uninterested third party.

It doesn't preclude criminal Alice from setting up this situation in advance given her intent to commit a crime, but it does seem to make it way harder.

While any kind of "digital notary" service would be enough to prove the minimum age of the data, but that's all it proves.

Consider a scenario where I generate a bajillion "predictions" of different winning lottery numbers, and I only unveil the one matching prediction--with provable age--while keeping all the non-matching ones hidden.

All good points, thank you

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