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by monson 2637 days ago
Securely signing a cryptographic message with a provable timestamp still requires a trusted third party, as far as I know. A trusted third party can be corrupted.[1]

Writing data on a decentralized blockchain inherently provides a secure timestamp that cannot be modified without being noticed. Not to mention the extreme costs involved with trying to rewrite a blockchain's history. [2]

I disagree with the parent comment on one thing-- I would much rather trust a public blockchain with a respectable hashrate over a private blockchain. You could simply store a salted hash of the data on the public blockchain, and still keep the actual evidence private.

[1] https://en.wikipedia.org/wiki/Trusted_third_party [2] https://en.wikipedia.org/wiki/Trusted_timestamping
1 comments
peteretep 2637 days ago
> still requires a trusted third party

That would be the judiciary. If they -- the people with the guns and the resources of the state -- become corrupted, you'd be unwise to think that your cryptographic signatures are going to help much.

In the example given, having lodged the evidence with the court would have prevented the abuse.

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monson 2637 days ago
> you'd be unwise to think that your cryptographic signatures are going to help much

It was you who suggested simple cryptographic signatures in your initial reply to the parent comment. I was only pointing out that securely signing a message with a timestamp requires a cryptographic entity known as a "Trusted Third Party". Please see the first link in my original comment.

> That would be the judiciary. If they -- the people with the guns and the resources of the state -- become corrupted, you'd be unwise to think that your cryptographic signatures are going to help much.

If there was verifiable proof on a globally distributed blockchain that evidence had been tampered with by a judiciary member of a democratic country, I find it very hard to believe they would get away with it in the long term.

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peteretep 2637 days ago
> I was only pointing out that

No, you were pointing it out and then saying that the flaw of this system was that the judiciary could be corrupted.

> If there was verifiable proof on a globally distributed blockchain that evidence had been tampered with by a judiciary member of a democratic country

Putting aside the many many political and practical ways in which this fantasy will stay firmly a fantasy, why does this need a blockchain instead of simply a published list of documents, if this is globally distributed?

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