10 ms·

Store the proof of a webpage saved with SingleFile in Bitcoin

107 points by gildas 7y ago

dqv 7y ago
Nice. I'll give it a try when I get to my primary PC. Journalists have a bad habit of linking to tweets which are often ephemeral because accounts are deleted, tweets are deleted, or accounts go private. Another problem is where publishers themselves change the open graph meta (or whatever it's called) after a tweet has been published. One memorable example (for me) is where Washington Post changed the image on an article about Alexandria Ocasio Cortez's Jewish heritage depicting her with her hands clasped similar to the Happy Merchant meme[0]. Obviously they realized the resemblance enough to change the image, but didn't comment on it. If you look at the original tweet[1] now, you can see the replies look completely out of context because they changed it. [0]:https://knowyourmeme.com/memes/happy-merchant https://knowyourmeme.com/memes/happy-merchant [1]:https://twitter.com/washingtonpost/status/1072124545560182784?lang=en https://twitter.com/washingtonpost/status/107212454556018278...
deleted 7y ago
[deleted]
sareum 7y ago
neat, this is really handy1
gill3s 7y ago
I use it every day to track bad takes / scams and prove them later just in case authors deny theirs words afterwards. Internet has good memory, Bitcoin make it immutable :)
verdverm 7y ago
Suspicious new accounts commenting
- kick 7y ago
  Interestingly, at least one deleted their comment after it was flagged, just in case any reader sees this and thinks "Wait, there's only two suspicious new accounts commenting!"
  - verdverm 7y ago
    HN will delete them too, I think. Both are now gone
    - kick 7y ago
      No, only one is. Turn showdead on.
kwantam 7y ago
Since there's little technical detail it's hard to be certain, but I doubt this is useful as a proof in the way one might wish (that is, proving that a web server delivered content X at date Y). The reason is, it does not appear that anything prevents the user from modifying the web page and then generating a "proof" about the modified version. TLSNotary (tlsnotary.org) is an example of a project that attempts to use a (modified) TLS connection for non-repudiation (which is roughly the property that we would want here), but it requires a trusted third party to act as the notary. It's possible this project is taking a similar approach (which would be fine, for those who trust the trusted third party). But given the lack of technical detail, and reading between the lines, I don't see a reason to believe this is the case. (Happy to be wrong, though! Maybe a more detailed description would help us understand what's going on.)
- gill3s 7y ago
  hi, I'm woleet's ceo. I can give you all the details you want. To explain it simply, for each signleFile export we "anchor" the hash in Bitcoin. It means each hash is link to one particular bitcoin transaction. Feel free to ask any question I'll be happy to answer
  - la_fayette 7y ago
    Actually, I also cannot find any information how this is actually achieved by your service. As OP mentioned, if "just" a browser extension is used to create a hash of the html page, one could use dev tools to modify the dom inside the browser and then create the hash...
  - mpeg 7y ago
    I think kwantam's point is that you are merely storing a hash of the resulting file, it proves it existed at a certain datetime, but it doesn't guarantee it wasn't modified (which TLSNotary does, albeit with a trusted third party required) This wasn't clear from the link, as there was very little technical information provided.
    - gill3s 7y ago
RileyJames 7y ago
Great solution. The previous blockchain enabled solution for this problem that I’d found was https://tlsnotary.org/ https://tlsnotary.org/. A few questions, how does notarising the tls handshake vs the entire document differ in terms of “proof”. Is one form of proof better than the other? Or do they prove something different?
deleted 7y ago
[deleted]
fiatjaf 7y ago
Why not use opentimestamps.org for this extension instead?
- maxfan8 7y ago
  Yeah, having an open, easy to verify standard is part of what makes a “proof” a good proof. No need to reinvent the wheel here.
  - gill3s 7y ago
    we do not reinvent the wheel here the proof generated is downloadable in the chainpoint format (https://w3id.org/chainpoint/v2 https://w3id.org/chainpoint/v2) and we also support Opentimstamps format. The verification tool allows you to download the chainpoint V2 format only though
onyb 7y ago
At my previous job, in a legal-tech company, we used Woleet to build a copyright protection product for intellectual property. However, I believe IPFS [1] is a superior solution for proof-of-existence, compared to timestamping on Bitcoin. With Woleet, you must keep the original payload (file + personal identification) that was timestamped, for eternity. In the event of a copyright violation, you must be able to prove in front of a judge that hash of the file in your possession is indeed what exists on the Bitcoin blockchain. With IPFS, you only need to save the hash of the payload (or a human-readable name, with IPNS [2]), to convince the judge that you authored the original file at a certain point in time. Additionally, IPFS has version control. This means that if you want to prove to a court that some revision to the T&Cs of your product were made before a certain date, it makes more sense to use IPFS. [1] https://ipfs.io https://ipfs.io [2] https://docs.ipfs.io/guides/concepts/ipns https://docs.ipfs.io/guides/concepts/ipns
- jmeyer2k 7y ago
  You can't prove a file existed before a certain date with IPFS like you can with Bitcoin.
  - capableweb 7y ago
    Yes, if I understand IPFS correctly, you can. Since IPFS works as a content addressed system, if you embed the date, send the document to the judge (the hash which is based on the content), don't show it until a later point, you can prove the document is the same as you sent, even without revealing the content until later. IPFS doesn't seem to have anything about "version control" as onyb mentioned.
    - tingletech 7y ago
      what prevents me from pre-dating a document on IPFS?
    - bluesign 7y ago
      how you will embed the date?
kichik 7y ago
Why not just timestamp it with RFC 3161 timestamp server? BitCoin sounds like a bit of an overkill here.
- eli 7y ago
  Or, for most people, just tweet a hash
  - gjs278 7y ago
    twitter can delete it
- XnoiVeX 7y ago
  Or a combined hash with the NIST randomness beacon. https://beacon.nist.gov/home https://beacon.nist.gov/home
  - maxfan8 7y ago
    Actually, uploading to Bitcoin is tantamount to using the NIST randomness beacon since the NIST randomness beacon is injected into Bitcoin: https://github.com/opentimestamps/nist-inject https://github.com/opentimestamps/nist-inject
joshspankit 7y ago
I believe this technique of storing hashes on a blockchain is how public figures should be inoculating against the upcoming risk posed by deepfakes. If a video surfaces that’s faked from an existing hashed one, that’s a very easy proof.
- exdsq 7y ago
  Solid idea actually! Can you think of a way to wrap this as a product?
  - joshspankit 7y ago
    Fun challenge. As a product it could be an independent video verification service. On-demand: A client wants to release a video and make sure that it’s trusted. They contact the company first, some process is done to make sure that they represent who they say they represent, and the content is hashed and added to the blockchain prior to release. Ongoing: when a client uploaded a video to the web, the system would automatically grab it, generate the hash, and add it to the blockchain along with the metadata of where it was found and who the client was. For large clients, it could even include video cold storage. For marketing/promotion, the company could automatically process public media from well-established social media feeds.
- maxfan8 7y ago
  How would this work? We’d still need something that can detect similar/probably deepfaked content (a good cryptographic hash has random distribution).
  - RobLach 7y ago
    Furthermore common actions such as re-encoding a video for streaming will generate a copy of the content that's identical but a completely different hash which will generate an ecosystem of real and deepfaked content with a similar amount of noise that deepfaked content thrives in.
  - gjs278 7y ago
mathiasrw 7y ago
A more complete way is to put all of the website data on the blockchain including metadata like https://etched.page https://etched.page does. Other files are added in a way that you can see how the page looked at the time. The user selects what files from the document is kept (.css is normally a good idea). The website, and the metadata about when it was stored including a signature from etched.page can be unpacked directly from chain.
- maxfan8 7y ago
  What’s wrong with just a hash of all the relevant files? You can then store the actual files conventionally and provide them upon request. The security guarantees are still there (you implicitly trust SHA256’s resistance against collision attacks if you use Bitcoin).
drdeca 7y ago
If webpages supported tls-N, then this seems like it could be cool, but as is, I don’t see what this does beyond what originstamp (and similar services) provide . The tls notary thing others have mentioned here sounds cool, and I hadn’t heard of it. The interactivity allowing for a proof even without the server supporting like tls-n is impressive, if I am understanding correctly!
realty_geek 7y ago
Is there a simple solution to allow people to timestamp a static webpage like Patrick McKenzie does here: https://twitter.com/patio11/status/958494488061595649 https://twitter.com/patio11/status/958494488061595649
zemnmez 7y ago
this is a proof that a user viewed a webpage rather than a proof that a webpage existed with given contents, which would need many users to find consensus on the content of a webpage. as a result of this model, there's no way to verify the content is 'correct', since the user can arbitrarily modify it before submitting so my understanding of this is that cryptographically it can be used to say that a user submitted some content at a given time. what's the use case for this?
- maxfan8 7y ago
  Prior art in patent, trademark, or copyright cases.
m-p-3 7y ago
Can we alternatively get the ability to upload that to IPFS?
crazypython 7y ago
I use DEVONThink, and it saves stuff in Web Archive (WARC) format when I want it to. Like Evernote clipper, but better. I also use httrack to download files offline, which I can then have DEVONThink index. Bam, offline search engine!
- solarkraft 7y ago
  While I'm intrigued and the personal version at 100$ looks okay, the server version (which is the only one I could use, as I have no device running an Apple OS) costs 500 fucking $! Does it even run on a Linux server? The website is super low on information.
marcinjachymiak 7y ago
There's already a better service that timestamps files in Bitcoin. It also uses blockchain space efficiently using servers that aggregate data that must be timestamped into a single Bitcoin transaction. You just need to publish a Merkle root and hold onto your Merkle proof. https://opentimestamps.org/ https://opentimestamps.org/ https://petertodd.org/2016/opentimestamps-announcement https://petertodd.org/2016/opentimestamps-announcement
aazaa 7y ago
The article is light on technical detail, but I presume this works by generating a hash value from the page of interest. Then a service such as opentimestamps (https://opentimestamps.org https://opentimestamps.org) gathers a bunch of these hashes together, publishing the Merkel root as data in an OP_RETURN transaction output. If so, one should be aware of a kinda sneaky attack that might be feasible. Let's say I want to prove my clairvoyance by predicting the winner of the 2020 presidential election. I generate a text file containing the name of my pick. Then I hash the result. Next, I publish the hash value to the block chain using an OP_RETURN output. On November 4, 2020, I publish the transaction ID containing the hash of my predicted winner. I also publish the text file used to generate the hash value. Clearly, I must have known that hash value when the transaction was confirmed, implying that I knew the winner of the election at that time as well. Except I cheated. Instead of making just one transaction, I made two. The second one contained an OP_RETURN output with the hash value of a document containing the name of the opponent. On the day after Election Day, I simply publish the transaction ID I know to contain the winner, and never mention the existence of the other transaction. Depending on how SingleFile works, it may be possible to do a similar attack. Also, you don't exactly get a proof that pinpoints the date. Rather, you get proof that the hash value existed as of the date the Bitcoin transaction gets its first confirmation.
- solotronics 7y ago
  I don't see this as a real issue because of course this protocol can only prove that a certain website existed as represented at that time. It's impossible to prove something didn't exist anyways. Can you prove I'm not wearing 8 different hats stacked on top of each other right now? No, impossible without a video recording and method of biometric verification both time-stamped showing I wasn't wearing the hats. This only works because there is arguably only one me at a time.
- msgilligan 7y ago
  This analysis is correct and it looks like SingleFile doesn't provide protection from this class of attack. However, there are solutions that can protect against this type of attack. The attack you describe above is similar to what is known as a "double-spend" attack. Using a digital signature you can prove that a particular key (and therefore user) signed a particular transaction, but cryptography alone cannot prove that there was not another competing transaction that spends the same funds. Prior to Bitcoin, digital currencies required a central database to prevent these double-spends. With Bitcoin and subsequent cryptocurrencies this attack is prevented via a distributed database with a consensus algorithm. Peter Todd (and others) have generalized prevention of double-spends to the idea of a "single-use seal" which can be implemented using the Bitcoin blockchain as an implementing decentralized service. [1] The idea is that there is some kind of formal protocol used (a higher layer in the protocol stack) and in the example above, the political prognosticator ties the hash of their single prediction of the winner of the presidential election to a particular Bitcoin UTXO (unspent transaction output) which serves a "single-use seal". The combination of the higher-layer messaging protocol and the "lock" to a single commitment tied to the UTXO limits the prognosticator to a single prediction. They don't have to reveal their prediction at the time it is made, but they do have to publicly (or privately) commit via a higher-level protocol to the single prediction. [1] https://petertodd.org/2016/commitments-and-single-use-seals https://petertodd.org/2016/commitments-and-single-use-seals Update: For the content hash of the (SingleFile) web page, you could have a sequence of these single-use seals each creating a new, linked transaction (UTXO) every time the website content is changed. This would allow users to verify the current content or what the content was at a particular time in history. As long as the root of this chain was somehow published (uniquely) at some start time in the past (in OpenSeals Terminology [2] this is called a "Root Proof". [2] https://github.com/rgb-org/spec/blob/develop/01-OpenSeals.md#definitions https://github.com/rgb-org/spec/blob/develop/01-OpenSeals.md...
stretchwithme 7y ago
This sort of thing is going to become very important for photos and videos. Being able to prove that an original earlier unaltered version of a video exists will allow us to reject AI-altered fake videos. Indeed, once it becomes commonplace, videos that do not have a blockchain record recorded close to creation time will be suspect. The less time an AI has to alter a video, the less likely alteration is.
Kinnard 7y ago
B:// Bitcoin Simple Storage Protocol https://b.bitdb.network https://b.bitdb.network C:// Content Addressable Files over Bitcoin https://c.bitdb.network https://c.bitdb.network
jonnydubowsky 7y ago
The Rebooting The Web of Trust workshops and conference represents an interesting intersection between self-sovereign identity authentication & verification, certificate validation, and reputation assessment. The website proof on btc blockchain seems to touch on these concepts. The W3C Digital Verification Community Group is working on a number of interesting solutions for digital verification as well. https://www.w3.org/community/digital-verification/ https://www.w3.org/community/digital-verification/ https://w3c-dvcg.github.io/http-signatures/ https://w3c-dvcg.github.io/http-signatures/ Does anyone have any experience working with the w3 digital verification stuff to help inform us on how this is progressing in the wild?
WhiteOwlLion 7y ago
You could use Bitcoin SV to store the actual file on the blockchain, but SingleFile creates an enormous HTML file. So, you're better off printing the page as a PDF, encode in the blockchain, and only spend 10% of what you would have spent (250kb SingleFile vs 25kb PDF).
- gildas 7y ago
  I can understand you prefer the PDF format for saving HTML webpages even though the PDF format is not adapted for this use-case. But do all the pages on the Internet saved with SingleFile weight 250KB and all the pages saved in PDF weight 25KB? I did a quick test by saving https://github.com/gildas-lormeau/SingleFile/issues?q=is%3Aissue+is%3Aclosed https://github.com/gildas-lormeau/SingleFile/issues?q=is%3Ai... and the HTML file generated by SingleFile is almost 3 times smaller than the PDF file. FYI, the SHA256 of the page is stored in Bitcoin, not the full page.

107 points by gildas 7y ago

dqv 7y ago

Nice. I'll give it a try when I get to my primary PC. Journalists have a bad habit of linking to tweets which are often ephemeral because accounts are deleted, tweets are deleted, or accounts go private. Another problem is where publishers themselves change the open graph meta (or whatever it's called) after a tweet has been published. One memorable example (for me) is where Washington Post changed the image on an article about Alexandria Ocasio Cortez's Jewish heritage depicting her with her hands clasped similar to the Happy Merchant meme[0]. Obviously they realized the resemblance enough to change the image, but didn't comment on it. If you look at the original tweet[1] now, you can see the replies look completely out of context because they changed it. [0]:https://knowyourmeme.com/memes/happy-merchant https://knowyourmeme.com/memes/happy-merchant [1]:https://twitter.com/washingtonpost/status/1072124545560182784?lang=en https://twitter.com/washingtonpost/status/107212454556018278...

deleted 7y ago

[deleted]

sareum 7y ago

neat, this is really handy1

gill3s 7y ago

I use it every day to track bad takes / scams and prove them later just in case authors deny theirs words afterwards. Internet has good memory, Bitcoin make it immutable :)

verdverm 7y ago

Suspicious new accounts commenting

kick 7y ago
Interestingly, at least one deleted their comment after it was flagged, just in case any reader sees this and thinks "Wait, there's only two suspicious new accounts commenting!"
- verdverm 7y ago
  HN will delete them too, I think. Both are now gone
  - kick 7y ago
    No, only one is. Turn showdead on.

kwantam 7y ago

Since there's little technical detail it's hard to be certain, but I doubt this is useful as a proof in the way one might wish (that is, proving that a web server delivered content X at date Y). The reason is, it does not appear that anything prevents the user from modifying the web page and then generating a "proof" about the modified version. TLSNotary (tlsnotary.org) is an example of a project that attempts to use a (modified) TLS connection for non-repudiation (which is roughly the property that we would want here), but it requires a trusted third party to act as the notary. It's possible this project is taking a similar approach (which would be fine, for those who trust the trusted third party). But given the lack of technical detail, and reading between the lines, I don't see a reason to believe this is the case. (Happy to be wrong, though! Maybe a more detailed description would help us understand what's going on.)

gill3s 7y ago
hi, I'm woleet's ceo. I can give you all the details you want. To explain it simply, for each signleFile export we "anchor" the hash in Bitcoin. It means each hash is link to one particular bitcoin transaction. Feel free to ask any question I'll be happy to answer
- la_fayette 7y ago
  Actually, I also cannot find any information how this is actually achieved by your service. As OP mentioned, if "just" a browser extension is used to create a hash of the html page, one could use dev tools to modify the dom inside the browser and then create the hash...
- mpeg 7y ago
  I think kwantam's point is that you are merely storing a hash of the resulting file, it proves it existed at a certain datetime, but it doesn't guarantee it wasn't modified (which TLSNotary does, albeit with a trusted third party required) This wasn't clear from the link, as there was very little technical information provided.
  - gill3s 7y ago

RileyJames 7y ago

Great solution. The previous blockchain enabled solution for this problem that I’d found was https://tlsnotary.org/ https://tlsnotary.org/. A few questions, how does notarising the tls handshake vs the entire document differ in terms of “proof”. Is one form of proof better than the other? Or do they prove something different?

deleted 7y ago

[deleted]

fiatjaf 7y ago

Why not use opentimestamps.org for this extension instead?

maxfan8 7y ago
Yeah, having an open, easy to verify standard is part of what makes a “proof” a good proof. No need to reinvent the wheel here.
- gill3s 7y ago
  we do not reinvent the wheel here the proof generated is downloadable in the chainpoint format (https://w3id.org/chainpoint/v2 https://w3id.org/chainpoint/v2) and we also support Opentimstamps format. The verification tool allows you to download the chainpoint V2 format only though

onyb 7y ago

At my previous job, in a legal-tech company, we used Woleet to build a copyright protection product for intellectual property. However, I believe IPFS [1] is a superior solution for proof-of-existence, compared to timestamping on Bitcoin. With Woleet, you must keep the original payload (file + personal identification) that was timestamped, for eternity. In the event of a copyright violation, you must be able to prove in front of a judge that hash of the file in your possession is indeed what exists on the Bitcoin blockchain. With IPFS, you only need to save the hash of the payload (or a human-readable name, with IPNS [2]), to convince the judge that you authored the original file at a certain point in time. Additionally, IPFS has version control. This means that if you want to prove to a court that some revision to the T&Cs of your product were made before a certain date, it makes more sense to use IPFS. [1] https://ipfs.io https://ipfs.io [2] https://docs.ipfs.io/guides/concepts/ipns https://docs.ipfs.io/guides/concepts/ipns

jmeyer2k 7y ago
You can't prove a file existed before a certain date with IPFS like you can with Bitcoin.
- capableweb 7y ago
  Yes, if I understand IPFS correctly, you can. Since IPFS works as a content addressed system, if you embed the date, send the document to the judge (the hash which is based on the content), don't show it until a later point, you can prove the document is the same as you sent, even without revealing the content until later. IPFS doesn't seem to have anything about "version control" as onyb mentioned.
  - tingletech 7y ago
    what prevents me from pre-dating a document on IPFS?
  - bluesign 7y ago
    how you will embed the date?

kichik 7y ago

Why not just timestamp it with RFC 3161 timestamp server? BitCoin sounds like a bit of an overkill here.

eli 7y ago
Or, for most people, just tweet a hash
- gjs278 7y ago
  twitter can delete it
XnoiVeX 7y ago
Or a combined hash with the NIST randomness beacon. https://beacon.nist.gov/home https://beacon.nist.gov/home
- maxfan8 7y ago
  Actually, uploading to Bitcoin is tantamount to using the NIST randomness beacon since the NIST randomness beacon is injected into Bitcoin: https://github.com/opentimestamps/nist-inject https://github.com/opentimestamps/nist-inject

joshspankit 7y ago

I believe this technique of storing hashes on a blockchain is how public figures should be inoculating against the upcoming risk posed by deepfakes. If a video surfaces that’s faked from an existing hashed one, that’s a very easy proof.

exdsq 7y ago
Solid idea actually! Can you think of a way to wrap this as a product?
- joshspankit 7y ago
  Fun challenge. As a product it could be an independent video verification service. On-demand: A client wants to release a video and make sure that it’s trusted. They contact the company first, some process is done to make sure that they represent who they say they represent, and the content is hashed and added to the blockchain prior to release. Ongoing: when a client uploaded a video to the web, the system would automatically grab it, generate the hash, and add it to the blockchain along with the metadata of where it was found and who the client was. For large clients, it could even include video cold storage. For marketing/promotion, the company could automatically process public media from well-established social media feeds.
maxfan8 7y ago
How would this work? We’d still need something that can detect similar/probably deepfaked content (a good cryptographic hash has random distribution).
- RobLach 7y ago
  Furthermore common actions such as re-encoding a video for streaming will generate a copy of the content that's identical but a completely different hash which will generate an ecosystem of real and deepfaked content with a similar amount of noise that deepfaked content thrives in.
- gjs278 7y ago

mathiasrw 7y ago

A more complete way is to put all of the website data on the blockchain including metadata like https://etched.page https://etched.page does. Other files are added in a way that you can see how the page looked at the time. The user selects what files from the document is kept (.css is normally a good idea). The website, and the metadata about when it was stored including a signature from etched.page can be unpacked directly from chain.

maxfan8 7y ago
What’s wrong with just a hash of all the relevant files? You can then store the actual files conventionally and provide them upon request. The security guarantees are still there (you implicitly trust SHA256’s resistance against collision attacks if you use Bitcoin).

drdeca 7y ago

If webpages supported tls-N, then this seems like it could be cool, but as is, I don’t see what this does beyond what originstamp (and similar services) provide . The tls notary thing others have mentioned here sounds cool, and I hadn’t heard of it. The interactivity allowing for a proof even without the server supporting like tls-n is impressive, if I am understanding correctly!

realty_geek 7y ago

Is there a simple solution to allow people to timestamp a static webpage like Patrick McKenzie does here: https://twitter.com/patio11/status/958494488061595649 https://twitter.com/patio11/status/958494488061595649

zemnmez 7y ago

this is a proof that a user viewed a webpage rather than a proof that a webpage existed with given contents, which would need many users to find consensus on the content of a webpage. as a result of this model, there's no way to verify the content is 'correct', since the user can arbitrarily modify it before submitting so my understanding of this is that cryptographically it can be used to say that a user submitted some content at a given time. what's the use case for this?

maxfan8 7y ago
Prior art in patent, trademark, or copyright cases.

m-p-3 7y ago

Can we alternatively get the ability to upload that to IPFS?

crazypython 7y ago

I use DEVONThink, and it saves stuff in Web Archive (WARC) format when I want it to. Like Evernote clipper, but better. I also use httrack to download files offline, which I can then have DEVONThink index. Bam, offline search engine!

solarkraft 7y ago
While I'm intrigued and the personal version at 100$ looks okay, the server version (which is the only one I could use, as I have no device running an Apple OS) costs 500 fucking $! Does it even run on a Linux server? The website is super low on information.

marcinjachymiak 7y ago

There's already a better service that timestamps files in Bitcoin. It also uses blockchain space efficiently using servers that aggregate data that must be timestamped into a single Bitcoin transaction. You just need to publish a Merkle root and hold onto your Merkle proof. https://opentimestamps.org/ https://opentimestamps.org/ https://petertodd.org/2016/opentimestamps-announcement https://petertodd.org/2016/opentimestamps-announcement

aazaa 7y ago

The article is light on technical detail, but I presume this works by generating a hash value from the page of interest. Then a service such as opentimestamps (https://opentimestamps.org https://opentimestamps.org) gathers a bunch of these hashes together, publishing the Merkel root as data in an OP_RETURN transaction output. If so, one should be aware of a kinda sneaky attack that might be feasible. Let's say I want to prove my clairvoyance by predicting the winner of the 2020 presidential election. I generate a text file containing the name of my pick. Then I hash the result. Next, I publish the hash value to the block chain using an OP_RETURN output. On November 4, 2020, I publish the transaction ID containing the hash of my predicted winner. I also publish the text file used to generate the hash value. Clearly, I must have known that hash value when the transaction was confirmed, implying that I knew the winner of the election at that time as well. Except I cheated. Instead of making just one transaction, I made two. The second one contained an OP_RETURN output with the hash value of a document containing the name of the opponent. On the day after Election Day, I simply publish the transaction ID I know to contain the winner, and never mention the existence of the other transaction. Depending on how SingleFile works, it may be possible to do a similar attack. Also, you don't exactly get a proof that pinpoints the date. Rather, you get proof that the hash value existed as of the date the Bitcoin transaction gets its first confirmation.

solotronics 7y ago
I don't see this as a real issue because of course this protocol can only prove that a certain website existed as represented at that time. It's impossible to prove something didn't exist anyways. Can you prove I'm not wearing 8 different hats stacked on top of each other right now? No, impossible without a video recording and method of biometric verification both time-stamped showing I wasn't wearing the hats. This only works because there is arguably only one me at a time.
msgilligan 7y ago
This analysis is correct and it looks like SingleFile doesn't provide protection from this class of attack. However, there are solutions that can protect against this type of attack. The attack you describe above is similar to what is known as a "double-spend" attack. Using a digital signature you can prove that a particular key (and therefore user) signed a particular transaction, but cryptography alone cannot prove that there was not another competing transaction that spends the same funds. Prior to Bitcoin, digital currencies required a central database to prevent these double-spends. With Bitcoin and subsequent cryptocurrencies this attack is prevented via a distributed database with a consensus algorithm. Peter Todd (and others) have generalized prevention of double-spends to the idea of a "single-use seal" which can be implemented using the Bitcoin blockchain as an implementing decentralized service. [1] The idea is that there is some kind of formal protocol used (a higher layer in the protocol stack) and in the example above, the political prognosticator ties the hash of their single prediction of the winner of the presidential election to a particular Bitcoin UTXO (unspent transaction output) which serves a "single-use seal". The combination of the higher-layer messaging protocol and the "lock" to a single commitment tied to the UTXO limits the prognosticator to a single prediction. They don't have to reveal their prediction at the time it is made, but they do have to publicly (or privately) commit via a higher-level protocol to the single prediction. [1] https://petertodd.org/2016/commitments-and-single-use-seals https://petertodd.org/2016/commitments-and-single-use-seals Update: For the content hash of the (SingleFile) web page, you could have a sequence of these single-use seals each creating a new, linked transaction (UTXO) every time the website content is changed. This would allow users to verify the current content or what the content was at a particular time in history. As long as the root of this chain was somehow published (uniquely) at some start time in the past (in OpenSeals Terminology [2] this is called a "Root Proof". [2] https://github.com/rgb-org/spec/blob/develop/01-OpenSeals.md#definitions https://github.com/rgb-org/spec/blob/develop/01-OpenSeals.md...

stretchwithme 7y ago

This sort of thing is going to become very important for photos and videos. Being able to prove that an original earlier unaltered version of a video exists will allow us to reject AI-altered fake videos. Indeed, once it becomes commonplace, videos that do not have a blockchain record recorded close to creation time will be suspect. The less time an AI has to alter a video, the less likely alteration is.

Kinnard 7y ago

B:// Bitcoin Simple Storage Protocol https://b.bitdb.network https://b.bitdb.network C:// Content Addressable Files over Bitcoin https://c.bitdb.network https://c.bitdb.network

jonnydubowsky 7y ago

The Rebooting The Web of Trust workshops and conference represents an interesting intersection between self-sovereign identity authentication & verification, certificate validation, and reputation assessment. The website proof on btc blockchain seems to touch on these concepts. The W3C Digital Verification Community Group is working on a number of interesting solutions for digital verification as well. https://www.w3.org/community/digital-verification/ https://www.w3.org/community/digital-verification/ https://w3c-dvcg.github.io/http-signatures/ https://w3c-dvcg.github.io/http-signatures/ Does anyone have any experience working with the w3 digital verification stuff to help inform us on how this is progressing in the wild?

WhiteOwlLion 7y ago

You could use Bitcoin SV to store the actual file on the blockchain, but SingleFile creates an enormous HTML file. So, you're better off printing the page as a PDF, encode in the blockchain, and only spend 10% of what you would have spent (250kb SingleFile vs 25kb PDF).

gildas 7y ago
I can understand you prefer the PDF format for saving HTML webpages even though the PDF format is not adapted for this use-case. But do all the pages on the Internet saved with SingleFile weight 250KB and all the pages saved in PDF weight 25KB? I did a quick test by saving https://github.com/gildas-lormeau/SingleFile/issues?q=is%3Aissue+is%3Aclosed https://github.com/gildas-lormeau/SingleFile/issues?q=is%3Ai... and the HTML file generated by SingleFile is almost 3 times smaller than the PDF file. FYI, the SHA256 of the page is stored in Bitcoin, not the full page.