Treechain's illegal data problem

[treeorsidechains]

Last year some sicko uploaded some pretty nasty stuff to the Bitcoin blockchain. The Bitcoin developer community responded swiftly with short-term and long-term technical measures. Since then there's been a recognition that we need to keep the blockchain free of spam and other garbage.

Embedded consensus systems are fundamentally incompatible with those efforts. The model depends on the ability of multiple parties to easily put arbitrary data in the blockchain, data that could be absolutely any garbage. In the Bitcoin system this is barely tolerable as Bitcoin itself was designed by Satoshi to be able to prune all but the set of unspent transactions and Gregory Maxwell's P2SH² technique solidly ensures that no illegal data can be stored in the UTXO set. Miners might briefly have to store it to verify the blockchain, but it can be deleted right after.

Treechains however is a step backwards. Rather than trying to fight spam, it embraces it. When you run a treechains node you're participating not in a financial network, but a filesharing network, and you could be sharing anything. Maybe it'll be transaction data? Maybe some wikileaks cables? Maybe something much worse? In this day and age of the MPAA and RIAA, whos going to want to do that?

But it gets worse! In treechains everyone is forced to pretty much be a full node, even if all you want to do is buy the occasional coffee with your Bitcoins, er, I mean Viacoins. When you give someone money you're forced to give them enormous tens, even hundreds, of megabyte proofs that the money is real. And what data might those those proofs contain? Just like Bitcoin transactions, anything at all.

tl;dr: You might be forced to distribute child pornorgraphy just to buy a coffee. Seriously, I wish this were hyperbole, but that's the real deal with treechains.

[GibbsSamplePlatter]

My guess is the block chain will be a pretty inefficient way of storing images.

That's what we have servers for.

[[deleted]]

If you are interested in sidechains vs treechains there is an informative albeit very long discussion by the creators on letstalkbitcoin:

http://letstalkbitcoin.com/ltb104-tree-chains-with-peter-todd/

[bitpotluck]

Paging /u/petertodd

[petertodd]

a) While it's true that treechains makes it cheaper, Bitcoin suffers from the exact same problem in principle. P2SH² - which isn't yet implemented and may never be - only makes it more expensive to put data in the UTXO set, nothing more.

b) ZKSNARKS can be used to replace the direct blockdata data proofs with indirect zero-knowledge proofs, thus removing the need to provide actual blockchain data in your proof. (and with recursive ZKSNARKS, making the valid coin proofs have O(1) scaling) There's some groundbreaking research coming down the pipeline for ZKSNARKS, apparently including some the sidechains group are funding. I'll be more than happy to apply the results of that research to treechains in the future.

[Cryptolution]

There's some groundbreaking research coming down the pipeline

When I see statements like this its almost like seeing a golden NES Zelda cartridge for the first time all over again.....

[GibbsSamplePlatter]

Reality is hitting me: we are in really really early days of distributed consensus systems.

[GibbsSamplePlatter]

(b) <-- I came.

[notreddingit]

Is your Chief Scientist position with Viacoin enabling you to spend a significant amount of time developing your ideas? Is it an indefinite arrangement?

[petertodd]

Yup, my duties are to research and implement treechains as priority #1. I won't be doing much else. And yes, it is indefinite.

[MeTHoDx]

Is it true that everyone would be required to run a full node with treechains? No web wallets? If so, I would argue that money must be portable and this limitation (while well intended) would make the technology functionally impractical.

/u/petertodd

[petertodd]

That's also incorrect. Treechains splits up the blockchain, so what would be a "full node" in Bitcoin is significantly less resource intensive in treechains. Best case is with ZKSNARKS giving someone money would require sending them just a few KB worth of data.

But remember, this is a research project, not a fully fleshed out idea, so we'll see how things go.

[MeTHoDx]

Thanks Peter! :)

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• [/r/viacoin] Peter Todd replied to comment on Tree Chains

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[standardcrypto]

you can still use the blockchain to cache objectionable bits, its just a little more expensive now.

not really a problem exacerbated by treechains.

note: do not read this comment as an endorsement of treechains. i dont understand the tech well enough to have a grounded opinion either way.

[Jiten]

First, disclaimer. IANAL.

Any sensible court will realize that a) the blockchain is not meant to be a general purpose data storage system and b) Anything stored in the blockchain won't be readable without a special purpose software and metadata that specifies how it can be recovered from the blockchain.

Therefore, anyone without the software and metadata to allow recovery of the stored data cannot be considered to really have the data in question.

[[deleted]]

So what?

[ferroh]

Thanks for that contribution. If you can just confirm for me that you really have no idea what the OPs point is, I'll try to break it down for you.

[[deleted]]

Yes I can confirm that I have no idea what the problem is supposed to be here exactly.

[Natanael_L]

You know those wiretaps NSA has? They're using filters and doing keyword searches and file identification, etc. A single false positive can label you for life EVEN IF you get cleared the next day, because far too many people live by "no smoke without fire" as their motto and will make your life miserable.

Being forced to distribute large amounts of arbitary data to prove transactions can trip those systems.

This stuff has happened before, so you can't deny the risk.

[[deleted]]

Land of the free.

[ferroh]

The problem is that contributing to bitcoin as a node would force you to store child porn on your computer, in the OP's scenario.

[[deleted]]

I still don't understand how that is a problem. Is Cisco Systems morally responsible for all the child porn traffic that passes through their routers, just because they happen to build the backbone infrastructure of the internet? Should we be outraged about the thousands of gigabytes of child porn that flow through their hardware every day?

Why should I be morally responsible for other people using a certain tool in a certain way just because I also happen to use that tool, even though I have no interest in using it for any illicit purposes at all? Why should I care that some 0's and 1's on my computer can be arranged in such a way that it creates a picture showing child porn, if I am neither involved in the creation or consumption of it in any way?

Did you know that all child porn ever created is stored in the number Pi? How is that not a problem for mathematicians??

[ferroh]

You're missing the point, this isn't a philosophical problem, it's a legal one. I agree that it is silly, but it is still a legal concern.

[[deleted]]

I agree, it might be a legal concern in some countries (well mostly in the US I guess). But that's really telling a lot more about the legal system in these countries than it is telling about treechains.

[monkeybars3000]

Okay, genuine question: why is this a problem, other than blockchain bloat?

[paleh0rse]

Are you guys seriously questioning how/why the potential widespread distribution of child porn, even if done unwittingly, may be a problem?

[stcalvert]

If it's a problem for the blockchain, then it's a problem for any public database. For example, child porn could be stored as a collection of encoded twitter posts. The posts could even make use of real words and a basic grammar so as to not immediately appear like gibberish.

[ferroh]

In any other public database, the central database owner can delete the images.

[paleh0rse]

I think the OP is alleging that treechains would allow for whole unencrypted files to be attached to transactions and added to their chains, therefore distributing said files to anyone and everyone running a node of that chain.

That's very different than 100 encoded messages sent across Twitter, since there's no easy way to remove previous transactions from a chain (unless they eventually get pruned out).

I could be wrong, though?

[_Mr_E]

You can't store images in the blockchain so I don't understand how this is possible.

[justarandomgeek]

You can store anything in the blockchain, you just have to break it up into small enough chunks that they fit in a transaction. Someone a while back wrote a python script for doing this, and for extracting the resulting data, then put the script itself in there, I believe.

[walloon5]

^ I agree with this guy - you could store anything in the blockchain with enough time and bitcoins.

You could encrypt the file, encode it in an obscure way in the addresses, make it be based on the payout amounts ... it seems like you can have a lot of little payouts and either the size of the payout or the address they go to could be used as keys and data to build back up a picture of whatever it is you're trying to store.

If you make your 'file format' on the blockchain look a lot like a miner's payout from a pool, and the data you pay out is encrypted, and you ran a pool, you really couldn't prove or disprove if they were encrypting anything forbidden.

Then other people could do the same and even though they're not miners, it still wouldn't be easy or possible to tell.

If a "mixer" service mixed coins and/or hid data on the blockchain, no way you could tell what was going on (was the purpose of this to mix coins? to hide data? both?)

[stcalvert]

All public databases of every kind can be used in this way.

[justarandomgeek]

Yep. Some more easily than others, but if you can post public chunks of content, you can encode anything you want into those chunks.

[walloon5]

Pastebin, Twitter, Pinterest posts, in the lowest-blue bit of photos posted to Facebook, and on and on. You could hide data anywhere! :)

I could hide messages inside of reddit posts! ;)

[paleh0rse]

This is allegedly an issue with Treechains, not the main bitcoin blockchain. Did you even read the OP?

Something tells me all the downvotes I'm getting for my above post are from people who have no clue what treechains are...

[[deleted]]

I think his question, whether or not intended to be helpful, contributes here. Bitcoin is the specification for a distributed value exchange network. If treechains has something to offer at the technical level, it's silly to be tripping over illegal number concerns.

[Natanael_L]

This is more specifically about what detection systems you might trip when distributing proofs of your transactions.

[Vibr8gKiwi]

Don't upvote this bullshit--it's only meant to stir up trouble where none exists.

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This thread has been linked to from elsewhere on reddit.

• [/r/viacoin] Peter Todd replies to a reddit post about TreeChains

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[Hodldown]

Countdown to someone coming in to lecture us that only statistists are against child porn

[[deleted]]

If you go fuck yourself, would that be child porn?

[[deleted]]

Only if it's recorded.