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An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

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Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#81

Post by Moodles »

jwilk wrote: post #62
chaz6 wrote: post #55

Earlier quoted context omitted.

I thought the same thing about PGP/GPG keyservers. They are supposed to be immutable so if someone uploaded a key containing a jpeg attachment depicting illegal content, the only course of action would be to wipe every server in the network.

Keys aren't immutable. You can remove UIDs you don't like. Even if they were immutable, at least in theory, a keyserver could censor whole keys. But apparently this is a practical problem. Phil Pennock wrote on oss-security ( http://seclists.org/oss-sec/2017/q4/375 ): [...] we've had keyservers in Europe shut down because of privacy demands because an append-only mesh-fill datastore can't remove keys and people send…

Indeed I was about to write as you have that key servers, or CT logs etc could arbitrarily decide not to include whatever keys they wanted -- although once included, it would be a pain to get rid of them because I think they're built on a Merkle tree structure which is routinely audited: I believe revoking a key doesn't actually delete a key from the database, but rather adds the statement "this key is now revoked", as it's an append-only ledger.

In theory the miners of a public blockchain could also do such auditing, to simply decide to ignore anything containing child pornography, just as they could arbitrarily decide to ignore any transactions. Of course, it's probably expensive to actually check all possible transaction in this way, and they most likely don't have a big enough incentive to. And of course for other sometimes illegal content (e.g. a picture of Mohammed or a particular nation's state secrets) some group of miners would censor while some wouldn't, and it would only take the miners who don't censor to win once for it to forever fork the blockchain.

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#82

Post by nradov »

mcny wrote: post #29
gambiting wrote: post #24

Earlier quoted context omitted.

I know it's controversial, but I think simply having any information should never be illegal - be it a manual on building bombs, detailed plans of the white house or yes, child porn. Obviously production of such material should be completely 10000% illegal, but we already have laws that cover this extensively. But simply having a written text, drawn picture, photograph or a video should never be illegal in itself.

> But simply having a written text, drawn picture, photograph or a video should never be illegal in itself. Exactly! However, reality is very sad. A map could potentially get you in prison in India https://archive.fo/nLtJX > The draft bill says: “No person shall depict, disseminate, publish or distribute any wrong or false topographic information of India including international boundaries through internet platforms…

India has active border disputes with both Pakistan and China. The concern is that if an Indian publisher produces maps which don't show the disputed areas as part of India then that would hurt their legal case in international tribunals and hand a propaganda victory to the other side. Land is the foundation of the state so it's not surprising that some governments react harshly to something their leaders perceive as an existential threat.

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#83

Post by simias »

VMG wrote: post #66
ddalex wrote: post #35

So the obvious bit here is that an adversarial actor can poison the blockchain with bits that make downloading, storing and processing the blockchain a highly illegal act. This may have a chilling effect on participating in the network, thus reducing the number of nodes, and undermining the trust on the blockchain and in the coin because the reduced requirement of computing power needed to mutate the blockchain. Acco…

The data embedded in the blockchain can only be extracted using custom tools. Custom tools can be used to extract any data from almost any other kind of other data, using steganography. You can extract illegal data from innocuous looking tweets, using the right tools.

If said tweets were reported they would (probably?) be deleted. I'm not sure the "custom tool" defense would really work, you could say the same thing for warez on usenet or even simple jpegs and videos, you need special codecs to view them. Furthermore even plain text embedded in the chain might be enough to get you in trouble in some jurisdiction if it contains hate speech, personal info or harassment material for instance.

The problem with the blockchain is actually its greatest strength: it's immutable. If somebody reports a block containing child porn there's no way to remove it without compromising the blockchain's integrity.

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#84

Post by jasode »

ddalex wrote: post #35

So the obvious bit here is that an adversarial actor can poison the blockchain with bits that make downloading, storing and processing the blockchain a highly illegal act. This may have a chilling effect on participating in the network, thus reducing the number of nodes, and undermining the trust on the blockchain and in the coin because the reduced requirement of computing power needed to mutate the blockchain. Acco…

>an adversarial actor can poison the blockchain with bits that make downloading, storing and processing the blockchain a highly illegal act.

Exactly. I brought up the same scenario recently.[1]

The top 2 replies to my comment was basically, "unless you're looking for illegal data, it's not a problem."

That head-in-the-sand ignorance completely misses the point. It's not about how _you_ specifically ignore illegal data and therefore, you have absolution of guilt. It's about the whole world's response to bad data in the blockchain.

[1] https://news.ycombinator.com/item?id=14434786

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#85

Post by zeth___ »

zaarn wrote: post #76
zeth___ wrote: post #67

Earlier quoted context omitted.

Slander and cyberbullying are civil law, not criminal law.

But it's just digital information, as you mentioned. It never enters flesh space as real.

Civil law is again very different to criminal law.

You can obviously have a contract between two people for sending digital information between them.

That this only happens in digital space does not mean the contract can't or shouldn't be enforced.

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#86

Post by VMG »

arcticfox wrote: post #79
VMG wrote: post #66

Earlier quoted context omitted.

The data embedded in the blockchain can only be extracted using custom tools. Custom tools can be used to extract any data from almost any other kind of other data, using steganography. You can extract illegal data from innocuous looking tweets, using the right tools.

That's a bit of a stretch. There's no reason to obfuscate anything (unless miners are actively and intentionally censoring content) and it'd be straightforward to make a browser. For example, I don't think it's a defense for the owner of a website to say "this horrible illegal content I'm sharing is only accessible via a custom tool that downloads and decodes image data from me...such as a web browser."

You can make a browser extension extracting illegal data from innocuous images on twitter

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#87

Post by alphydan »

Tepix wrote: post #53
bb88 wrote: post #8

Earlier quoted context omitted.

> What will a country do if someone embeds child pornography or a picture of Mohammed or something in the blockchain? In the US at least, I'd hope that we probably wouldn't criminalize 1M people for the actions of 1. Hopefully in other countries they wouldn't do that either.

There is a possibility of a technical solution: - You create a special rule for a block known to contain illegal data. - The illegal data in the block gets NULLed. The other transactions are left untouched. - The checksum for the next block is no longer calculated, instead it is hardcoded. This means there is no way of verifying the transactions in that block. Perhaps you add a new signature for the block with the NU…

Wouldn't that allow a 'denial-of-service' like attack? You keep sending illegal content over and over and the next block is never attained.

Maybe I am misunderstanding the process.

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#88

Post by pjc50 »

ckastner wrote: post #61
oasisbob wrote: post #52

This gets close to something else I've been pondering lately - how to deal with immutable data structures in the realm of GDPR. Recitations in GDPR require systems to be designed with privacy in mind. Immutable structures like the Bitcoin blockchain or Merkle trees in other applications would seem to be fundamentally incompatible with some GDPR privacy requirements. Let's say Google receives a valid right to be forgo…

> Recitations in GDPR require systems to be designed with privacy in mind. Immutable structures like the Bitcoin blockchain or Merkle trees in other applications would seem to be fundamentally incompatible with some GDPR privacy requirements. And against whom would I claim my rights, for example: my right to be forgotten ( Article 17: The data subject shall have the right to obtain from the controller the erasure of…

Every person running a full node would theoretically be a controller in that case. But as you say, you could probably make a "business requirements" case if it's just a certificate. Right to be forgotten does not include the right to demand people forget that you owe them money, for example.

What gets more complex is if you put non-business-related "sensitive" personal data in an immutable system, e.g. if you're building an illegal blacklist of union organisers.

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#89

Post by Moodles »

gsich wrote: post #10
Moodles wrote: post #6

Some interesting graffiti on the bitcoin blockchain: http://www.righto.com/2014/02/ascii-bernanke-wikileaks-photo... I have always wondered this. What will a country do if someone embeds child pornography or a picture of Mohammed or something in the blockchain? Will it then be illegal to store the blockchain in that country? Is a link to such an image much different to an actual image? It seems hard to ever stop this…

The first one would be horrible. The second one, eeh who cares. Not much you can do about it anyway.

Just to be clear: I'm not suggesting we should implement blasphemy laws :-)

Re: An Analysis of the Impact of Arbitrary Blockchain Content on Bitcoin [pdf]

#90

Post by zone411 »

Not too long ago, I checked the number of images that were posted on the Ethereum blockchain and I also posted a test image (https://etherscan.io/tx/0x3ee5575306ddc235b0586984172888b47e...). There were 74 images with headers that appeared as jpg, gif, or png already posted before my test image. It's very easy to post to the Ethereum blockchain: just convert back and forth from file to hex using a site like http://tomeko.net/online_tools/hex_to_file.php?lang=en. You might also have to calculate how much gas will be used. I opened a few images and I saw a couple selfies but the oldest jpeg is a certain infamous image from 1999 that I don't think anybody cares to see. I anticipated the chance of illegal images (though it's not exactly a novel idea so I figured somebody would notice it has happened by now if an illegal image has been on the blockchain for a while), so I haven't opened others.
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