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You could create a QR based on the last block of BITCOIN blockchain. These way you do not rely on a private key and onyone can check and trust it.

by fbn79 5y ago

can16358p 5y ago
Remimds me of Vitalik Buterin holding a paper with a new block's hash and posting his photo when there were rumors about him being dead a few years ago.
- deleted 5y ago
  [deleted]
- thamer 5y ago
  I hadn't heard of this, this is a pretty cool way to provide this proof. Back story: https://www.coindesk.com/markets/2017/06/26/proof-of-life-vitalik-buterin-uses-ethereum-to-disprove-death-hoax/ https://www.coindesk.com/markets/2017/06/26/proof-of-life-vi... The block in question (open "Click to see more" and look for the "Hash" field): https://etherscan.io/block/3930000 https://etherscan.io/block/3930000
avnigo 5y ago
That reminds me something like the OpenTimestamps project: https://opentimestamps.org/ https://opentimestamps.org/
- amelius 5y ago
  Have these stamps already been tested in a court of law?
  - rosndo 5y ago
    This question doesn’t make any sense, there’s nothing to “test”. An irrefutable cryptographic timestamp is just that, irrefutable. Sometimes courts make mistakes, but you can’t expect any useful precedent over something like this.
    - amelius 5y ago
      Most of cryptography can in theory always be brute-forced or simply guessed. There is no absolute guarantee, though you can get very very close. And there are other ways around it, such as keys getting leaked. Also, because of lack of expertise courts may simply not want to deal with this kind of proof and thus not acknowledge it.
      - rosndo 5y ago
        > Also, because of lack of expertise courts may simply not want to deal with this kind of proof and thus not acknowledge it. Courts lack expertise on almost every subject, I don’t think this logic can actually hold up.
        amelius 5y ago
        Perhaps, but the other points I brought up might.
        rosndo 5y ago
        No, not really. Opentimestamps addresses all of them. Opentimestamps cannot be bruteforced, and there are no keys that could leak. Bruteforcing would require for you to permanently take over the entire bitcoin network.
      - miunau 5y ago
        I believe at that point it's up to the lawyers to argue. It's up to persons with people skills to convince other people that something is not fake, using tools like these as assistance, not as clinchers.
      - slaymaker1907 5y ago
        You could probably make it work, but it would likely involve some expensive expert witnesses.
    - ohyeshedid 5y ago
      > An irrefutable cryptographic timestamp is just that, irrefutable. In math, sure, but he specifically asked about a court of law. Irrefutable in math doesn't mean admissible in court. Then there's the 1, 6, 12, or however many random people that decide the case; they likely need the math explained to them, and two sides get turns convincing them the other is wrong.
miunau 5y ago
This is certainly a possible implementation and good if you would want to base it on the chain, doable via a minimal node. It would not work offline though, which would make it harder to use in frontline reporting, so I think the spec itself should not specify such a requirement.
- 3np 5y ago
  Qrdate involves server-side signing and does not work offline either? If the signature involves a hash of a bitcoin block we don't have to trust the site owner to not sign future timestamps.
  - miunau 5y ago
    There's two proposed ways specified. The web way (called "Dynamic") and a fingerprint-based implementation that can work offline ("Static"), for example in approved apps for some organisations: https://github.com/qrdate/qrdate#static-qr-date-v1-spec https://github.com/qrdate/qrdate#static-qr-date-v1-spec It is still a concept as there's no implementation of it besides the tests in the repo, so it would require further refining for production apps. For example with specifying key exchange formats, which we are looking at right now. Anyone with expertise in this field wanting to contribute is welcome!
jeroenhd 5y ago
But what would that solve? The blocks on the blockchain are public, so anyone can fake a timestamp by grabbing an old block and generating a QR code. The point of this website is that the server signs the timestamp. It's more than just a QR code with a time and date, it has some actual verification code.
- itake 5y ago
  you wouldn't need to use their website and the service would be completely decentralized. the website has the exact same problem that you pointed out for the blockchain: you can screen capture a QR code and re-use it later.
  - ricardobeat 5y ago
    No, you can’t. It’s one of the main features, explained right there in the page.
    - itake 5y ago
      > It does not work against the past (taking snapshots of the code and using them later) Right on the page, it says this. Maybe I am not understanding your point. Both the website and the blockchain strategy make it impossible for you to record video content and claim it happened in the future, but neither of them defend against recording after the timestamp happened. The blockchain strategy does not require a centralized service, while the QR code requires the website to be up forever.
      - miunau 5y ago
        You can always use the published public key to verify the signature. There's also a way to generate the codes offline using a certificate chain and a fingerprint (https://github.com/qrdate/qrdate#static-qr-date-v1-spec https://github.com/qrdate/qrdate#static-qr-date-v1-spec) which does not require a website, just a key store. It needs more specifying to be viable for real world use but it should be possible. Help is very welcome.

You could create a QR based on the last block of BITCOIN blockchain. These way you do not rely on a private key and onyone can check and trust it.

by fbn79 5y ago

You could create a QR based on the last block of BITCOIN blockchain. These way you do not rely on a private key and onyone can check and trust it.

can16358p 5y ago

Remimds me of Vitalik Buterin holding a paper with a new block's hash and posting his photo when there were rumors about him being dead a few years ago.

deleted 5y ago
[deleted]
thamer 5y ago
I hadn't heard of this, this is a pretty cool way to provide this proof. Back story: https://www.coindesk.com/markets/2017/06/26/proof-of-life-vitalik-buterin-uses-ethereum-to-disprove-death-hoax/ https://www.coindesk.com/markets/2017/06/26/proof-of-life-vi... The block in question (open "Click to see more" and look for the "Hash" field): https://etherscan.io/block/3930000 https://etherscan.io/block/3930000

avnigo 5y ago

That reminds me something like the OpenTimestamps project: https://opentimestamps.org/ https://opentimestamps.org/

amelius 5y ago
Have these stamps already been tested in a court of law?
- rosndo 5y ago
  This question doesn’t make any sense, there’s nothing to “test”. An irrefutable cryptographic timestamp is just that, irrefutable. Sometimes courts make mistakes, but you can’t expect any useful precedent over something like this.
  - amelius 5y ago
    Most of cryptography can in theory always be brute-forced or simply guessed. There is no absolute guarantee, though you can get very very close. And there are other ways around it, such as keys getting leaked. Also, because of lack of expertise courts may simply not want to deal with this kind of proof and thus not acknowledge it.
    - rosndo 5y ago
      > Also, because of lack of expertise courts may simply not want to deal with this kind of proof and thus not acknowledge it. Courts lack expertise on almost every subject, I don’t think this logic can actually hold up.
      - amelius 5y ago
        Perhaps, but the other points I brought up might.
        rosndo 5y ago
        No, not really. Opentimestamps addresses all of them. Opentimestamps cannot be bruteforced, and there are no keys that could leak. Bruteforcing would require for you to permanently take over the entire bitcoin network.
    - miunau 5y ago
      I believe at that point it's up to the lawyers to argue. It's up to persons with people skills to convince other people that something is not fake, using tools like these as assistance, not as clinchers.
    - slaymaker1907 5y ago
      You could probably make it work, but it would likely involve some expensive expert witnesses.
  - ohyeshedid 5y ago
    > An irrefutable cryptographic timestamp is just that, irrefutable. In math, sure, but he specifically asked about a court of law. Irrefutable in math doesn't mean admissible in court. Then there's the 1, 6, 12, or however many random people that decide the case; they likely need the math explained to them, and two sides get turns convincing them the other is wrong.

miunau 5y ago

This is certainly a possible implementation and good if you would want to base it on the chain, doable via a minimal node. It would not work offline though, which would make it harder to use in frontline reporting, so I think the spec itself should not specify such a requirement.

3np 5y ago
Qrdate involves server-side signing and does not work offline either? If the signature involves a hash of a bitcoin block we don't have to trust the site owner to not sign future timestamps.
- miunau 5y ago
  There's two proposed ways specified. The web way (called "Dynamic") and a fingerprint-based implementation that can work offline ("Static"), for example in approved apps for some organisations: https://github.com/qrdate/qrdate#static-qr-date-v1-spec https://github.com/qrdate/qrdate#static-qr-date-v1-spec It is still a concept as there's no implementation of it besides the tests in the repo, so it would require further refining for production apps. For example with specifying key exchange formats, which we are looking at right now. Anyone with expertise in this field wanting to contribute is welcome!

jeroenhd 5y ago

But what would that solve? The blocks on the blockchain are public, so anyone can fake a timestamp by grabbing an old block and generating a QR code. The point of this website is that the server signs the timestamp. It's more than just a QR code with a time and date, it has some actual verification code.

itake 5y ago
you wouldn't need to use their website and the service would be completely decentralized. the website has the exact same problem that you pointed out for the blockchain: you can screen capture a QR code and re-use it later.
- ricardobeat 5y ago
  No, you can’t. It’s one of the main features, explained right there in the page.
  - itake 5y ago
    > It does not work against the past (taking snapshots of the code and using them later) Right on the page, it says this. Maybe I am not understanding your point. Both the website and the blockchain strategy make it impossible for you to record video content and claim it happened in the future, but neither of them defend against recording after the timestamp happened. The blockchain strategy does not require a centralized service, while the QR code requires the website to be up forever.
    - miunau 5y ago
      You can always use the published public key to verify the signature. There's also a way to generate the codes offline using a certificate chain and a fingerprint (https://github.com/qrdate/qrdate#static-qr-date-v1-spec https://github.com/qrdate/qrdate#static-qr-date-v1-spec) which does not require a website, just a key store. It needs more specifying to be viable for real world use but it should be possible. Help is very welcome.