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> The hard part is actually proving a message existed after some point in time. It's interesting that we think about this exactly opposite! It has been possib

by lucb1e 6y ago

> The hard part is actually proving a message existed after some point in time. It's interesting that we think about this exactly opposite! It has been possible since a long time (relative to the existence of the internet) to prove something existed after some point in time by cryptographically tying a news headline to your message. That's what Satoshi used if I'm not mistaken[1], or at least I remember this being used before blockchain. If you want to do it the other way around, you needed a trusted third party up until Bitcoin came around and there was a method that did not rely on a single third party. One issue I see with blockchains is that they require a running and ongoing service to prevent backdating. A witness also works, but is just moving the problem (it can be a solution, but it's not a general solution that works in every situation). To me it still seems that the easy way around is the one that is solvable with an ordinary newspaper. Edit: I see in your GitHub bio (sorry for the stalking, I was curious about your age since you seem to consider blockchain to be the more generally available than newspapers, whereas to (perhaps older) me, newspapers are the generally available method and blockchain novel) that you describe yourself as a "Applied Cryptography Consultant (what the cool kids call 'blockchain tech')". I suppose that explains why we see this as opposite. [1] Also looked up the newspaper that Satoshi used. Wikipedia says: `Embedded in the coinbase transaction of [the genesis] block was the text: "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"` https://en.wikipedia.org/wiki/Satoshi_Nakamoto https://en.wikipedia.org/wiki/Satoshi_Nakamoto

petertodd 6y ago
Yes, I'm well aware of what Satoshi used. The thing is, the famous "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks" quote that's in the genesis block only proves that the genesis block hash was created after Jan 3rd, 2009. The quote does not prove that the rest of the genesis block was created after that date. That distinction is why random beacons are tricky to use. Sometimes that distinction doesn't matter, sometimes it does. It depends on what exactly you are trying to accomplish. With the Bitcoin genesis block this isn't a problem, as the purpose of the genesis block quote is to show that blocks after the genesis block weren't generated in advance. But in other use-cases - eg the "proof of life via newspaper" example - deep fakes make the security of a random beacon much more dubious. > I was curious about your age since you seem to consider blockchain to be the more generally available than newspapers, whereas to (perhaps older) me, newspapers are the generally available method and blockchain novel I'm wasn't trying to make that claim one way or another. Regardless of what exact type of random beacon you use, the problem I describe above still exists. Now, if you actually do have one of the rare use-cases where random beacons work, these days using Bitcoin as your random beacon is certainly better suited to automation. But whether or not that's relevant depends on what exactly you're trying to achieve.

by lucb1e 6y ago

petertodd 6y ago

Yes, I'm well aware of what Satoshi used. The thing is, the famous "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks" quote that's in the genesis block only proves that the genesis block hash was created after Jan 3rd, 2009. The quote does not prove that the rest of the genesis block was created after that date. That distinction is why random beacons are tricky to use. Sometimes that distinction doesn't matter, sometimes it does. It depends on what exactly you are trying to accomplish. With the Bitcoin genesis block this isn't a problem, as the purpose of the genesis block quote is to show that blocks after the genesis block weren't generated in advance. But in other use-cases - eg the "proof of life via newspaper" example - deep fakes make the security of a random beacon much more dubious. > I was curious about your age since you seem to consider blockchain to be the more generally available than newspapers, whereas to (perhaps older) me, newspapers are the generally available method and blockchain novel I'm wasn't trying to make that claim one way or another. Regardless of what exact type of random beacon you use, the problem I describe above still exists. Now, if you actually do have one of the rare use-cases where random beacons work, these days using Bitcoin as your random beacon is certainly better suited to automation. But whether or not that's relevant depends on what exactly you're trying to achieve.