8 ms·

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 i

by ddalex 9y ago

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. Accordingly a determined actor with enough resources (e.g. a nation-state) can render the bitcoin value-less and use-less at will....

phkahler 9y ago
In addition to illegal content, one could just put a huge amount of data in there to accelerate what seems to be a built in problem of ever increasing storage requirements.
- paulgb 9y ago
  The size of each block is fixed, and the transaction fee is proportional to the number of bytes in the transaction, so you could block people from making transactions (if you were willing to outbid them) but couldn't make the chain grow faster.
  - gcb0 9y ago
    hence you can only do that if you have enough money. and that is exactly what visa is doing.
    - redblacktree 9y ago
      What visa is doing? Can you elaborate?
- icelancer 9y ago
  >> one could just put a huge amount of data in there That, ah, isn't how that works. You can't just dump terabytes into the blockchain for BTC, LTC, or really any blockchain I can think of that has any sort of adoption.
  - dharma1 9y ago
    Always wondered how IPFS deals with this
    - setra 9y ago
      IPFS is not an automatically distributed file store. Just like torrents if someone wants to host a petabyte they can. That does not mean anyone else will be mirroring it.
    - robto 9y ago
      IPFS isn't a blockchain, and you only receive data you request - it's pull instead of push oriented. So I don't believe it has any problem with this.
    - insanity54 9y ago
      +1 to Setra's comment. Regarding illegal content, IPFS gateways have a blacklist https://github.com/ipfs/infrastructure/blob/master/ipfs/gateway/denylist.conf https://github.com/ipfs/infrastructure/blob/master/ipfs/gate...
- TazeTSchnitzel 9y ago
  There's a 1MB cap on block size and it's already being met.
chaz6 9y ago
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.
- jwilk 9y ago
  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 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 out their email address and name paired into a key and then get upset because it's out there; we're one illicit-material-in-photo-uid incident away from global shutdown.
  - Moodles 9y ago
    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.
- simias 9y ago
  Keyservers are convenient but they're not critical to PGP's functionality. There are other ways to distribute public keys. Actually in general public key servers are only mildly useful because you can't really trust anything you get from them, you have to use your web of trust of some other way to validate that the key is valid. On the other hand if you wipe (even partially) Bitcoin's blockchain your basically destroy the currency.
VMG 9y ago
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.
- zaarn 9y ago
  If the extraction tools do not exceed the cryptographic complexity of a OTP cipher, I doubt that any court will accept that excuse. It's the difference between taking random bits of your computer to assemble illegal content vs taking one specific set of bits and applying mere transforms to then to retrieve illegal content.
- arcticfox 9y ago
  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."
  - VMG 9y ago
    You can make a browser extension extracting illegal data from innocuous images on twitter
    - OscarCunningham 9y ago
      Only by using your own stock of illegal data.
      - otherwiseguy 9y ago
        Bingo.
      - VMG 9y ago
jmcqk6 9y ago
Especially if you consider the possibility of someone loading state secrets onto the chain. It wouldn't take a state actor to initiate that action, but that state actor could render the chain worthless.
- otherwiseguy 9y ago
  That isn't as much of an issue. Once a secret is out, it is out. Something like child porn would be permanently illegal and permanently stored in the chain. Imagine hiding it there, letting a year or two of transactions build upon it before letting people know it was there. You can't remove it. The blockchain is now technically illegal. I was just thinking about this a lot this week, actually. The really crazy thing is that, due to the PROTECT Act, a person in Japan could legally upload certain manga that the US would consider CP. So one wouldn't even have to risk jail to poison the blockchain.
  - lopmotr 9y ago
    I think child porn laws are too one-size-fits-all. It's supposed to be to be a disincentive to abusing children to produce the images for profit. Once it's well and truly public so the profit motive is gone, it should become legal. Or at least at the same status as revenge porn if the subjects are identifiable. Unfortunately, most people are too puritanical to even dare to think about the topic, let alone opens debate it or soften the law.
    - sgt101 9y ago
      Every time one of those images is viewed it's an attack on the person in it, the person who could not, and never can give their consent. Also the normalisation of the behavior in the images enables abusers. The law is there to protect children, profit doesn't feature in the calculations.
      - lopmotr 9y ago
        Viewing an image obviously doesn't harm anyone directly. What's the chain of causation between that act and the harm, assuming no payment. Normalization of behavior is a worry that always comes up with "immoral" information. Violent movies, violent video games, adult porn, strip clubs, prostitution, open homosexuality, etc. You'd need actual evidence to support the claim that it makes things worse not better or neutral.
jasode 9y ago
>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 https://news.ycombinator.com/item?id=14434786
- deleted 9y ago
  [deleted]
elmar 9y ago
and the developers of the software what would be the legal standing if they are residents of countries like the USA? could they be persecuted as facilitators of the ilegal distribution?

by ddalex 9y ago

phkahler 9y ago

In addition to illegal content, one could just put a huge amount of data in there to accelerate what seems to be a built in problem of ever increasing storage requirements.

paulgb 9y ago
The size of each block is fixed, and the transaction fee is proportional to the number of bytes in the transaction, so you could block people from making transactions (if you were willing to outbid them) but couldn't make the chain grow faster.
- gcb0 9y ago
  hence you can only do that if you have enough money. and that is exactly what visa is doing.
  - redblacktree 9y ago
    What visa is doing? Can you elaborate?
icelancer 9y ago
>> one could just put a huge amount of data in there That, ah, isn't how that works. You can't just dump terabytes into the blockchain for BTC, LTC, or really any blockchain I can think of that has any sort of adoption.
- dharma1 9y ago
  Always wondered how IPFS deals with this
  - setra 9y ago
    IPFS is not an automatically distributed file store. Just like torrents if someone wants to host a petabyte they can. That does not mean anyone else will be mirroring it.
  - robto 9y ago
    IPFS isn't a blockchain, and you only receive data you request - it's pull instead of push oriented. So I don't believe it has any problem with this.
  - insanity54 9y ago
    +1 to Setra's comment. Regarding illegal content, IPFS gateways have a blacklist https://github.com/ipfs/infrastructure/blob/master/ipfs/gateway/denylist.conf https://github.com/ipfs/infrastructure/blob/master/ipfs/gate...
TazeTSchnitzel 9y ago
There's a 1MB cap on block size and it's already being met.

chaz6 9y ago

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.

jwilk 9y ago
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 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 out their email address and name paired into a key and then get upset because it's out there; we're one illicit-material-in-photo-uid incident away from global shutdown.
- Moodles 9y ago
  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.
simias 9y ago
Keyservers are convenient but they're not critical to PGP's functionality. There are other ways to distribute public keys. Actually in general public key servers are only mildly useful because you can't really trust anything you get from them, you have to use your web of trust of some other way to validate that the key is valid. On the other hand if you wipe (even partially) Bitcoin's blockchain your basically destroy the currency.

VMG 9y ago

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.

zaarn 9y ago
If the extraction tools do not exceed the cryptographic complexity of a OTP cipher, I doubt that any court will accept that excuse. It's the difference between taking random bits of your computer to assemble illegal content vs taking one specific set of bits and applying mere transforms to then to retrieve illegal content.
arcticfox 9y ago
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."
- VMG 9y ago
  You can make a browser extension extracting illegal data from innocuous images on twitter
  - OscarCunningham 9y ago
    Only by using your own stock of illegal data.
    - otherwiseguy 9y ago
      Bingo.
    - VMG 9y ago

jmcqk6 9y ago

Especially if you consider the possibility of someone loading state secrets onto the chain. It wouldn't take a state actor to initiate that action, but that state actor could render the chain worthless.

otherwiseguy 9y ago
That isn't as much of an issue. Once a secret is out, it is out. Something like child porn would be permanently illegal and permanently stored in the chain. Imagine hiding it there, letting a year or two of transactions build upon it before letting people know it was there. You can't remove it. The blockchain is now technically illegal. I was just thinking about this a lot this week, actually. The really crazy thing is that, due to the PROTECT Act, a person in Japan could legally upload certain manga that the US would consider CP. So one wouldn't even have to risk jail to poison the blockchain.
- lopmotr 9y ago
  I think child porn laws are too one-size-fits-all. It's supposed to be to be a disincentive to abusing children to produce the images for profit. Once it's well and truly public so the profit motive is gone, it should become legal. Or at least at the same status as revenge porn if the subjects are identifiable. Unfortunately, most people are too puritanical to even dare to think about the topic, let alone opens debate it or soften the law.
  - sgt101 9y ago
    Every time one of those images is viewed it's an attack on the person in it, the person who could not, and never can give their consent. Also the normalisation of the behavior in the images enables abusers. The law is there to protect children, profit doesn't feature in the calculations.
    - lopmotr 9y ago
      Viewing an image obviously doesn't harm anyone directly. What's the chain of causation between that act and the harm, assuming no payment. Normalization of behavior is a worry that always comes up with "immoral" information. Violent movies, violent video games, adult porn, strip clubs, prostitution, open homosexuality, etc. You'd need actual evidence to support the claim that it makes things worse not better or neutral.

jasode 9y ago

>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 https://news.ycombinator.com/item?id=14434786

deleted 9y ago
[deleted]

elmar 9y ago

and the developers of the software what would be the legal standing if they are residents of countries like the USA? could they be persecuted as facilitators of the ilegal distribution?