Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

proofofexistence.com

Post reply on HN
Print view View original

21–30 of 44 posts

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#21

Post by socrates1024 »

notacoward wrote: post #11

I'm not exactly a big Bitcoin booster, but I love the way techniques and structures developed for it are being adapted to uses like this. Given that this seems very similar to el33th4xor's Virtual Notary, how would one distinguish between the strengths or use cases of the two? http://hackingdistributed.com/2013/06/20/virtual-notary-intr...

Technical differences aside, proofofexistence.com predates the Cornell team's blogpost by a couple of months.[2] I am not surprised that the Cornell team did not cite the bitcointalk forum post (given the recent frenzy of their Selfish Mining paper, where they neglected to cite a fairly closely related forum post from two years earlier). However, a published paper, CommitCoin,[1] predates both of these by about a year.

I don't believe there is any meaningful technical difference among these.

[1] Clark, Jeremy, and Aleksander Essex. "CommitCoin: Carbon dating commitments with bitcoin." Financial Cryptography and Data Security. Springer Berlin Heidelberg, 2012. 390-398.

[2] www.proofofexistence.com - Upload a document and have it certified by the Bitcoin blockchain bitcointalk user: maraoz https://bitcointalk.org/index.php?topic=212701.0

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#22

Post by cuu508 »

AlexSolution wrote: post #12
Patient0 wrote: post #5

"This is why the bitcoins sent in this special transaction are unspendable, as the addresses are being generated from the document's hash fragments instead of from a private ECDSA key." I hadn't realised before that this means that you can provably "destroy" bitcoins. That is, you can "prove" that a certain bitcoin amount will never be spent again by anyone including yourself...

Could you please elaborate on this? I understand neither your comment, nor the part that you quoted from the site.

To spend coins from given address, you need its corresponding private key. They can demonstrate that, the way they generate these addresses, they can't know the private keys. Or possibly matching private keys might not exist at all. In that case, as an analogy, think of unix account with disabled password, the password hash in /etc/shadow is "!". There is no password which has a hash "!". So effectively it is impossible to log in with password.

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#23

Post by runn1ng »

rdtsc wrote: post #4

This makes me think of another thing I was wondering about -- can some entity that doesn't like having Bitcoin around for whatever reason, DDoS it by filling it with meaningless transactions. Maybe just setting up 100 addresses and constantly transferring small payments between them, filling the transaction history with garbage. Is that possible, and is there any protection against that?

Some people say that is exactly what SatoshiDICE is doing :)

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#24

Post by gwern »

JulianMorrison wrote: post #20

Bitcoin would be an awesome "dead drop" for untraceable communication of small data.

Actually, we already have such things like alt.anonymous and they work well in practice; see my just submitted https://news.ycombinator.com/item?id=6819799

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#26

Post by emin-gun-sirer »

notacoward wrote: post #11

I'm not exactly a big Bitcoin booster, but I love the way techniques and structures developed for it are being adapted to uses like this. Given that this seems very similar to el33th4xor's Virtual Notary, how would one distinguish between the strengths or use cases of the two? http://hackingdistributed.com/2013/06/20/virtual-notary-intr...

Virtual Notary offers a superset of the document verification service offered by proofofexistence.com.

It's best to think of Virtual Notary as a impartial online witness to factoids that can be checked online. Besides documents, it can attest to the content of web pages, tweets, weather conditions, stock prices, exchange rates, employment status (for those institutions where we know how to check employment status), house features and prices, etc.

It can also issue official, certified random numbers.

Virtual Notary also allows the users to download an independently-verifiable X509 certificate of attestation.

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#27

Post by alexwright »

jawr wrote: post #9
Patient0 wrote: post #5

"This is why the bitcoins sent in this special transaction are unspendable, as the addresses are being generated from the document's hash fragments instead of from a private ECDSA key." I hadn't realised before that this means that you can provably "destroy" bitcoins. That is, you can "prove" that a certain bitcoin amount will never be spent again by anyone including yourself...

Yeah, the fact that bitcoins can be permanently destroyed is a little bit worrying, one of BTC's benefits is it's cap. What's the economical consequences of these coins being destroyed?

You can burn fiat cash, and fire gold bars into space. What are the consequences of those actions? Other coins are presumably worth more because there are now fewer of them.

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#29

Post by icebraining »

drakaal wrote: post #25
JulianMorrison wrote: post #20

Bitcoin would be an awesome "dead drop" for untraceable communication of small data.

Except you'd have to spend some money, so the origin would always be known.

There are still some Bitcoin Faucets open, such as FreeCoins[1]. They give out almost nothing, but it's enough to make transactions just for the registration, and you don't need to provide any information.

[1] http://freecoins.herokuapp.com/

Re: Proof of Existence: Storing Hashed Files in the Bitcoin Block Chain

#30

Post by emin-gun-sirer »

socrates1024 wrote: post #21
notacoward wrote: post #11

I'm not exactly a big Bitcoin booster, but I love the way techniques and structures developed for it are being adapted to uses like this. Given that this seems very similar to el33th4xor's Virtual Notary, how would one distinguish between the strengths or use cases of the two? http://hackingdistributed.com/2013/06/20/virtual-notary-intr...

Technical differences aside, proofofexistence.com predates the Cornell team's blogpost by a couple of months.[2] I am not surprised that the Cornell team did not cite the bitcointalk forum post (given the recent frenzy of their Selfish Mining paper, where they neglected to cite a fairly closely related forum post from two years earlier). However, a published paper, CommitCoin,[1] predates both of these by about a yea…

Timestamping services are not novel and date way back before 2012. The earliest work I know of is from AT&T back in the 80's, where they proposed to publish the hash in the NYT. The idea was so well established that there is even an RFC [1] from 2001. And by the way, virtual-notary.org was online for several months or perhaps even a year before the blog post.

But the important differences are actually technical. Virtual Notary is a much more general service, offering to attest to any kind of online factoid. Let's elevate the discussion here -- it doesn't matter who was there first (because the AT&T folks were there two decades before both services), what matters is who offers the most useful service [3].

As for the previous work on selfish mining, see here [2].

[1] http://www.ietf.org/rfc/rfc3161.txt

[2] http://hackingdistributed.com/2013/11/09/no-you-dint/

[3] https://news.ycombinator.com/item?id=6819835

Post reply on HN