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Reading the https://proofofexistence.com/about https://proofofexistence.com/about is really helpful, because I really didn't understand this at all. While this

Reading the https://proofofexistence.com/about https://proofofexistence.com/about is really helpful, because I really didn't understand this at all. While this is interesting, is there any concern about over use of the bitcoin blockchain? It's currently 65GB in size[0], which means it's fairly usable, and with a big enough system you could still store the entire thing in memory. What happens when it's 65TB? 65PB? Won't using it for lots and lots of things cause issues long term? Or am I missing something here? [0] https://blockchain.info/charts/blocks-size?timespan=all https://blockchain.info/charts/blocks-size?timespan=all

ikeboy 11y ago
Eventually you'll be able to trim some parts, and only full nodes will need to store everything. The code is not quite ready yet, though. I believe there were plans to include a hash of the unspent transactions set in each block, so you could have effectively the same security by only verifying the block headers up to the latest block, and the unspent transactions set. Not sure if they ended up including that, though. There were a couple other interesting proposals along the same lines as well.
- thescriptkiddie 11y ago
  You can already tell the bitcoin client to prune old blocks, because theoretically you don't need to keep any blocks more than a few hours old as long as you maintain a database with the last known ownership of every coin. In the future you could expect a setting to have the client ignore coins you don't control and crunch the entire db down to less than 1 GiB.
  - ikeboy 11y ago
    Yeah, but you still need to download all of them at least once to ensure there aren't missing transactions. The proposal with the UTXO set would allow you to only download headers+UTXO.
    - thescriptkiddie 11y ago
      Yes, you do currently have to download the whole blockchain at least once. I can't remember if you have to save the whole thing before pruning begins or if it can prune as it goes along. Hopefully the headers+UTXO proposal will be implemented soon, as the total size of the headers is only 32 MiB (80 bytes per block) and the total size of the UTXO set is only 1.2 GiB. We've already dramatically reduced the bandwidth requirements with Xtreme Thinblocks, so storage cost is the major limiting factor for running a node.
  - TylerE 11y ago
    Of every address. There is no such thing as a bitcoin.
    - thescriptkiddie 11y ago
      Sorry, I have a bad habit of using "coin" to mean UTXO. You actually don't care about every address, only the ones with balance.
vesinisa 11y ago
This service only stores the hash of the document in the blockchain, so it only increases the size of the DB marginally. The tendency for the blockchain DB to grow is in part limited by that storing anything in the blockchain requires a transaction, and transactions cost money, which goes to the miners, who in turn bear the expenses of storing the DB as part of their mining equipment.
- cloudjacker 11y ago
  two years ago I tried to store the hashes of everyone's unique DNA in the blockchain in a parseable format even compressed it was completely untenable space-wise due to the amount of people this would need to support and secondly the amount of transactions the network supports so........ you're wrong. I think proofofexistence.com existed at that time as well so why is this even news? bitcoin's been around for a whiiiiiiile
- retube 11y ago
  Yes but the bitcoin blockchain isn't just used for storing doc hashes
enraged_camel 11y ago
That "About" page was frustrating to read. It talks about "common uses" without talking about actual use cases. Like, no realistic scenarios where this thing would come in handy. What industries would it be particularly useful in? Legal? Real estate? Logistics? The press releases at the bottom talk about it having potential to be used as a notary service, but even those are lacking detail. edit: getting downvoted by bitcoin fanboys. should have seen that coming!
- niij 11y ago
  The only obvious use I could think of is proof of invention of some idea. Like the old "Mail a letter to your self and don't open it proof".
  - bobwaycott 11y ago
    Exactly the same as my first thought.
- detaro 11y ago
  Funny, for me the page actually mentions two applications. (But without any evidence that it would actually hold up in court, which tends to be the thing that matters in such cases)
  - teawrecks 11y ago
    Well, it's mathematically provable, so...Just need a judge who permits logic in court. Good luck with that.
- bobwaycott 11y ago
  Did you really have no ideas of your own of realistic scenarios after reading that page? I find that not entirely surprising, I guess, but your tone certainly is.
- alasano 11y ago
  I'm building a fun little service based on storing the hash of a document created by user input. I think it can be very useful and even fun if presented the right way.

ikeboy 11y ago

Eventually you'll be able to trim some parts, and only full nodes will need to store everything. The code is not quite ready yet, though. I believe there were plans to include a hash of the unspent transactions set in each block, so you could have effectively the same security by only verifying the block headers up to the latest block, and the unspent transactions set. Not sure if they ended up including that, though. There were a couple other interesting proposals along the same lines as well.

thescriptkiddie 11y ago
You can already tell the bitcoin client to prune old blocks, because theoretically you don't need to keep any blocks more than a few hours old as long as you maintain a database with the last known ownership of every coin. In the future you could expect a setting to have the client ignore coins you don't control and crunch the entire db down to less than 1 GiB.
- ikeboy 11y ago
  Yeah, but you still need to download all of them at least once to ensure there aren't missing transactions. The proposal with the UTXO set would allow you to only download headers+UTXO.
  - thescriptkiddie 11y ago
    Yes, you do currently have to download the whole blockchain at least once. I can't remember if you have to save the whole thing before pruning begins or if it can prune as it goes along. Hopefully the headers+UTXO proposal will be implemented soon, as the total size of the headers is only 32 MiB (80 bytes per block) and the total size of the UTXO set is only 1.2 GiB. We've already dramatically reduced the bandwidth requirements with Xtreme Thinblocks, so storage cost is the major limiting factor for running a node.
- TylerE 11y ago
  Of every address. There is no such thing as a bitcoin.
  - thescriptkiddie 11y ago
    Sorry, I have a bad habit of using "coin" to mean UTXO. You actually don't care about every address, only the ones with balance.

vesinisa 11y ago

This service only stores the hash of the document in the blockchain, so it only increases the size of the DB marginally. The tendency for the blockchain DB to grow is in part limited by that storing anything in the blockchain requires a transaction, and transactions cost money, which goes to the miners, who in turn bear the expenses of storing the DB as part of their mining equipment.

cloudjacker 11y ago
two years ago I tried to store the hashes of everyone's unique DNA in the blockchain in a parseable format even compressed it was completely untenable space-wise due to the amount of people this would need to support and secondly the amount of transactions the network supports so........ you're wrong. I think proofofexistence.com existed at that time as well so why is this even news? bitcoin's been around for a whiiiiiiile
retube 11y ago
Yes but the bitcoin blockchain isn't just used for storing doc hashes

enraged_camel 11y ago

That "About" page was frustrating to read. It talks about "common uses" without talking about actual use cases. Like, no realistic scenarios where this thing would come in handy. What industries would it be particularly useful in? Legal? Real estate? Logistics? The press releases at the bottom talk about it having potential to be used as a notary service, but even those are lacking detail. edit: getting downvoted by bitcoin fanboys. should have seen that coming!

niij 11y ago
The only obvious use I could think of is proof of invention of some idea. Like the old "Mail a letter to your self and don't open it proof".
- bobwaycott 11y ago
  Exactly the same as my first thought.
detaro 11y ago
Funny, for me the page actually mentions two applications. (But without any evidence that it would actually hold up in court, which tends to be the thing that matters in such cases)
- teawrecks 11y ago
  Well, it's mathematically provable, so...Just need a judge who permits logic in court. Good luck with that.
bobwaycott 11y ago
Did you really have no ideas of your own of realistic scenarios after reading that page? I find that not entirely surprising, I guess, but your tone certainly is.
alasano 11y ago
I'm building a fun little service based on storing the hash of a document created by user input. I think it can be very useful and even fun if presented the right way.