6 ms·

The Flaw that May Bring Down Bitcoin or Change it Forever

75 points by thetabyte 13y ago

frisco 13y ago
There's already a proposal floating around on the dev list to introduce a new address type, P2SH^2, which would allow the relevant data fields currently being used to stuff the info discussed in the article to become hashes. This would have the effect that if you wanted to stuff arbitrary data, you'd be limited to finding hash collisions. See the thread here: http://sourceforge.net/mailarchive/message.php?msg_id=30705609 http://sourceforge.net/mailarchive/message.php?msg_id=307056... I've been lurking on the bitcoin-dev list for a while to observe how they handle issues just like this. I'm confident that these problems will be transient.
- daveasdf 13y ago
  While such a scheme might solve this particular method of storing data, it won't make the general problem go away. For instance, if I want to publish an 'n' byte message, I could generate 'n' wallets, each having as their final byte of their fingerprint the n'th byte of my message. Constructing 'n' such wallets will require on average "256*n/2" units of work---quite small, all things considered. I can then transfer a single bitcoin to each wallet in turn, forming a linked list of the bytes in my message. Even better, I also get my coin back at the end.
  - Groxx 13y ago
    Minus transaction fees, yes.
- gizmo686 13y ago
  It doesn't seem like hashing the data fields reduces the problem to finding collisions. Say I hash 2 values. I can distribute these and say H1 corresponds to a '1', and H2 corresponds to '0'. Now, I can store 1 bit of arbitrary data per transaction. Of course, I can increase the amount of data per transaction by exponentially increasing my initial work (and the size of the lookup table). But given that transactions are cheep, I would not need to compute the complete rainbow table to make this practical, and you only need to do the hashing once.
- sneak 13y ago
  Entirely unnecessary. Transaction fees address the crapflooding issue, and the fact that you can embed only a very small amount of arbitrary data in each transaction means that you're unlikely to be able to harm someone else by forcing them to "possess" your various short byte sequences (which will, on disk, of course be interspersed with the rest of the transaction data). This is to say nothing about the fact that everyone else running bitcoin will also possess these bytes in their blockchains, making the possession of them rather unextraordinary. This whole article is just the latest in "Bitcoin doomed to fail, and here's why!" bullshit that's been going on for what feels like a decade but is really only 3 years or so.
  - new299 13y ago
    This is actually a big issue for bitcoin, I don't think we should avoid it by saying it's the "standard bullshit". We also not really talking about small amounts of data (at least at the moment) a few megabytes is relatively significant... I think the fact that it's "unextraordinary" to possess this data is the interesting thing. That may force a legal distinction which in itself pushes us toward a different understanding of "illegal data" and that perhaps the legal system has to give up on that and move towards accessing or "distributing with intent" being the illegal rather than just possession.
Xcelerate 13y ago
I would think the solution to this problem is to somehow prove to the blockchain that the address was indeed produced by the SHA256 RIPEMD160 process. I would think mathematically there is some way to do this without revealing what it was you hashed. I mean, you can verify that you are who you say you are simply by using your private key to sign a message; I would think a comparable process would work for this. EDIT: Facepalm; you're hashing the public key. You don't need to hide that. See my comment below.
- gizmo686 13y ago
  Two points. First, crypto is hard. Unless a system is proven to have a certain property, assume the worst case scenario for your system. Second, SHA256, RIPEMD160 are hashes. By definition (of an ideal hashing algorithm), every output can be generated with the same probability, and changing a single bit of the input will have a 50% chance of changing a given output bit.
  - Xcelerate 13y ago
    I am familiar with how hashes work (I've written a Bitcoin address generator myself). To illustrate what I mean: The Bitcoin address is just some chain of hashes (and a checksum) applied to the public key. To prove that the address IS actually output from the hash functions [and not spam], simply provide the public key along with it. Of course, you might say that is way too much data for the blockchain to handle. So you only limit the requirement of providing the public key to "suspicious" transactions. What constitutes a suspicious transaction could be a matter of debate, but I imagine it could be done, and it would avoid the problem of a Bitcoin's value depending on its ancestry.
    - drivebyacct2 13y ago
      Yeah, I think there is actually WIP to do something along the lines of what you worked out. However, I'm not sure what good identifying "suspicious transactions" is going to do. They're not reversible. You can't really make any attempt to "blacklist" them - you'll almost surely lose.
rockyleal 13y ago
I think there is a lot of sensationalism in the way this issue has been aproached. To inject data into the blockchain in this way is comparable (although not identical) to writing the same 'evil urls' in a dollar bill with a pen, and then passing it around. It is a problem that exists in a different layer than the currency, even if it is to some degree 'passed on' through the currency. Likewise, the solution (imho) lies in a different layer: detect a cp link in the blockchain? Great, take down the link, problem solved. Just as it is not the fault of TCP/IP, or its 'downfall', that it is able to transmit 'evil data', it is not Bitcoin's fault what vandals sometimes write on it.
- daveasdf 13y ago
  While you likely have a point that this is being sensationalised, the money analogy isn't quite accurate. The problem is that such "evil" messages can be broadcast globally without the ability to remove them. A dollar bill with a message on it can be taken out of circulation; the bitcoin blockchain can't be reset without major chaos ensuing.
  - new299 13y ago
    Interesting the act of marking coins with messages is not new. In Ireland coins used to get marked with political messages from the UVF and others, I believe it was quite common for a time. http://www.cointalk.com/t195082/ http://www.cointalk.com/t195082/
- aneth4 13y ago
  This is wrong on all points. A dollar bill is seen by an infitesimally small number of users as opposed to 100% of full bitcoin nodes. Dollar bills are also transient and easy to destroy, whereas the blockchain is permanent and forever. Finally, there is no entity that could determine unacceptable content or delete it, and if there were it would carry the standard abuse problems of any censorship program. So while the issue may or may not be sensationalized, writing ignorant and wholly incorrect commentary is not the antidote.
  - 13y ago
tyre 13y ago
This will neither bring bitcoin down or change it forever. Any information contained in those bytes is just that: information. What can you say in 20 bytes that can have permanent, material damage to human beings? A wonderfully sensationalist title, but really nothing to back it up.
- jerf 13y ago
  "What can you say in 20 bytes that can have permanent, material damage to human beings?" The AACS encryption key was 16 bytes: http://en.wikipedia.org/wiki/AACS_encryption_key_controversy http://en.wikipedia.org/wiki/AACS_encryption_key_controversy In general, private keys are in that range of byte size.
  - sneak 13y ago
    They were, indirectly, drawing attention the non-import of that particular byte sequence - it literally does not matter, and the whole thing was to illustrate that a) you can't censor tiny speech effectively and b) DRM is doomed and the keys will always be reverse-engineered. Saying something meaningful enough to get someone jailed for possessing a drive with the string on it (the criteria for this to be actually harmful to bitcoin) is nearly impossible in 20 bytes in most parts of the developed world. The article is sensationalist bullshit.
    - jerf 13y ago
      "Saying something meaningful enough to get someone jailed for possessing a drive with the string on it (the criteria for this to be actually harmful to bitcoin) is nearly impossible in 20 bytes in most parts of the developed world." In a sensible legal regime, sure. In a legal regime looking for an excuse to shut down BitCoin? Easily done. Technically the AACS key is still illegal. I think the latter rather than the former is more accurately the threat. But then, if a legal regime is looking to shut down BitCoin they already have plenty of avenues. It already looks an awful lot like money laundering, for instance. So this line of thought is garbage... but only because there's no way any legal system would have to stretch this far to attack BitCoin, because they've got a wide variety of far more plausible attacks. It's not exactly the BitCoin-friendly line of argument you might be hoping for.
scottmcleod 13y ago
Title seems irrelevant. My prediction is we will see coins dedicated to just this purpose.
- abrkn 13y ago
  https://bitmessage.org/ https://bitmessage.org/
ck2 13y ago
I guess they should have disallowed vowels eh? Has spam appeared yet? Because you know that is next.
- spullara 13y ago
  Without anyone actively looking at it, addressee spam probably won't matter. If you could send from a chosen address you might have a point though as it would show up in people's wallets.
LAMike 13y ago
What's the worst thing you can transmit with 20 bytes? A link to a website? A couple of the 7 words? A "yo mama" joke? C'mon this is a BS linkbait article
- ceejayoz 13y ago
  A link to child pornography, perhaps, with which law enforcement would have an excuse to make any selected bitcoin user's life a living hell.
  - hobs 13y ago
    or... take down the link.
    - ceejayoz 13y ago
      Isn't the point of the article that the link is in the block chain itself?
  - jasonzemos 13y ago
    A link to something isn't possession of something. Any URL might become worthless anyway once the real offending source material is removed.
    - ceejayoz 13y ago
      We live in a world where folks like Aaron Swartz get driven to suicide by overzealous prosecutors, and you don't think law enforcement could use that sort of thing as an excuse to harass you?
  - sneak 13y ago
    A link to insert boogeyman here which is also on the hard disks of a few hundred thousand other people, downloaded automatically, and stored in a file with a dozen other gigs of bitcoin transaction data. Sounds like an airtight case.
moxie 13y ago
Travis Goodspeed and Dan Kaminksy demonstrated this in 2011 by embedding a tribute to the late Len Sassaman in the blockchain: http://pastebin.com/raw.php?i=BUB3dygQ http://pastebin.com/raw.php?i=BUB3dygQ
eurleif 13y ago
Kind of like how somewhere, within the digits of pi, there's all sorts of criminal data. http://everything2.com/title/Converting+Pi+to+binary%253A+Don%2527t+do+it%2521 http://everything2.com/title/Converting+Pi+to+binary%253A+Do...
tlrobinson 13y ago
This brings up some interesting questions. One could also XOR some illegal data with the text of the US Constitution, then claim that the Constitution "contains" that data, you just need to XOR it with this particular key. Obviously that's absurd, but where do you draw the line? You need specialized software and the 32 byte transaction ID in order to extract the data. What other permanent public records could be manipulated like this?
- batgaijin 13y ago
  That's the principle behind the OFF P2P system: http://en.wikipedia.org/wiki/Owner_free_filing_system http://en.wikipedia.org/wiki/Owner_free_filing_system US legal system is based on intent so it's kind of pointless.
AnthonyMouse 13y ago
The flaw in all of this is that you're embedding 20 bytes in the blockchain. In order to do that, you have to choose an encoding method. In order to get the embedded data back out, you have to convey the encoding method and which block is encoded with it to the recipient. Which is totally pointless because if you can convey that to the recipient then you might as well just use the same communications method to convey the original message. The only plausible reason not to would be if the law prohibits the message but not the information about how to construct the message from the blockchain (and even that is not guaranteed). Even then all you would accomplish is to cause the government to pass a new law that prohibits you from telling anyone that a prohibited link is encoded in the block in the same way that you're currently prohibited from telling anyone the link itself. The real problem here is not that child pornographers would actually use bitcoin to distribute links, it's that assholes who want to damage bitcoin would put contraband in the blockchain in order to cause legal trouble for innocent users. But I think that's a broader problem than just bitcoin. You can encode anything into anything. Take anything anyone else has posted and xor it with something you want to encode. The output will resemble garbage rather than either input. But now you can post the "garbage" and instructions on what to xor it with to allow anyone to recover your encoded message, and the poster of the other message becomes an unwilling participant in your encoding scheme. It clearly makes no sense to punish distributors of the original message just because the encoded message is contraband. Which doesn't mean there won't be laws that will punish it anyway, but that is the fight that needs to be won -- to not allow stupid laws that would punish innocent people.
- new299 13y ago
  The "encoding method" is ASCII text. The data can be extracted by running "strings *.dat" on the block chain on any UNIX system. After that you can grep through the output. This is not like XORing data, or as some people have said "everything occurs somewhere in the digits of pi". The blockchain in no sense encodes all possible values, or a fraction thereof, the data is trivial to extract. This is much more like, it's sitting on the webserver, but not indexed by google. It's actually even worse than that because you can still just grep through the blockchain and find what your interested in. This may or may not be a problem for bitcoin, but I think it is legally problematic at the moment. This may move us toward a world where it's not illegal to store any particular data or even distribute it. The illegal act might be the viewing or "distribution with intent" or the data. I think that would be an interesting development. Personally as a user of Bitcoin I've deleted the standard qt client, I personally don't want that data on my computer. I now use a blockchainless client (Electrum).
siculars 13y ago
Of all the things threatening bitcoin this is by far the least worrisome. What if people start writing links to censored/illegal content on circulating dollar bills? Nothing, that's what.
- ema 13y ago
  You can just throw away a dollar bill with illegal stuff on it. You can not throw away the data of a bitcoin transaction without throwing away all transaction which occurred later on the block chain.
- hackerboos 13y ago
  Bad analogy. There aren't copies of said dollar bill in the wallet/purse of everyone that uses dollar bills.
drivebyacct2 13y ago
Am I wrong in thinking that this is some sort of "freedom of speech" and that it isn't necessarily wholly different than Bitcoin's sense of "hands off, let it be, decentralization, no one can control/stifle/limit/etc"?
dasil003 13y ago
How is this any different than a government declaring bitcoin illegal for whatever legal reasoning they can come up with? It's not practical to shut down everyone with a bitcoin database any more than it's practical to raid every server with wikileaks data. If they're going to declare this nuclear war on bitcoin it's not going to be on the basis of some piece of data which by the point it's in the blockchain is out of the bag anyway.
TheEskimo 13y ago
I believe that there is an even more important practical issue. What if someone manages to embed something very much like the EICER string[0] in it? How many people do you think would use the bitcoin client on windows if their AV automatically deleted the blockchain as it downloaded in a misguided attempt to protect them? Of course, first we have to know if this is possible at all. Does anyone know if there's either a) 20 bytes with a very high AV detection rate or b) some way to embed more than 20 bytes in a row in the block chain? [0]: http://en.wikipedia.org/wiki/EICAR_test_file http://en.wikipedia.org/wiki/EICAR_test_file
- oleganza 13y ago
  After a couple of times when AV deletes the blockchain, it will either be uninstalled by the user, or fixed by its developer. Not a big deal.
andr3w321 13y ago
Can someone post the command to create these messages or at least tell me what portion of the transaction this is being stored under? I am curious. My chain is a bit out of date, but I was able to generate the messages http://pastebin.com/wdpF4L4k http://pastebin.com/wdpF4L4k ~/.bitcoin/blocks $ ls | xargs strings -n 20 | tee ~/Downloads/hiddenblockchain.txt https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_Calls_list https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_Calls... Are they just sending coins to an invalid address (their string)?

75 points by thetabyte 13y ago

There's already a proposal floating around on the dev list to introduce a new address type, P2SH^2, which would allow the relevant data fields currently being used to stuff the info discussed in the article to become hashes. This would have the effect that if you wanted to stuff arbitrary data, you'd be limited to finding hash collisions. See the thread here: http://sourceforge.net/mailarchive/message.php?msg_id=30705609 http://sourceforge.net/mailarchive/message.php?msg_id=307056... I've been lurking on the bitcoin-dev list for a while to observe how they handle issues just like this. I'm confident that these problems will be transient.

daveasdf 13y ago
While such a scheme might solve this particular method of storing data, it won't make the general problem go away. For instance, if I want to publish an 'n' byte message, I could generate 'n' wallets, each having as their final byte of their fingerprint the n'th byte of my message. Constructing 'n' such wallets will require on average "256*n/2" units of work---quite small, all things considered. I can then transfer a single bitcoin to each wallet in turn, forming a linked list of the bytes in my message. Even better, I also get my coin back at the end.
- Groxx 13y ago
  Minus transaction fees, yes.
gizmo686 13y ago
It doesn't seem like hashing the data fields reduces the problem to finding collisions. Say I hash 2 values. I can distribute these and say H1 corresponds to a '1', and H2 corresponds to '0'. Now, I can store 1 bit of arbitrary data per transaction. Of course, I can increase the amount of data per transaction by exponentially increasing my initial work (and the size of the lookup table). But given that transactions are cheep, I would not need to compute the complete rainbow table to make this practical, and you only need to do the hashing once.
sneak 13y ago
Entirely unnecessary. Transaction fees address the crapflooding issue, and the fact that you can embed only a very small amount of arbitrary data in each transaction means that you're unlikely to be able to harm someone else by forcing them to "possess" your various short byte sequences (which will, on disk, of course be interspersed with the rest of the transaction data). This is to say nothing about the fact that everyone else running bitcoin will also possess these bytes in their blockchains, making the possession of them rather unextraordinary. This whole article is just the latest in "Bitcoin doomed to fail, and here's why!" bullshit that's been going on for what feels like a decade but is really only 3 years or so.
- new299 13y ago
  This is actually a big issue for bitcoin, I don't think we should avoid it by saying it's the "standard bullshit". We also not really talking about small amounts of data (at least at the moment) a few megabytes is relatively significant... I think the fact that it's "unextraordinary" to possess this data is the interesting thing. That may force a legal distinction which in itself pushes us toward a different understanding of "illegal data" and that perhaps the legal system has to give up on that and move towards accessing or "distributing with intent" being the illegal rather than just possession.

Xcelerate 13y ago

I would think the solution to this problem is to somehow prove to the blockchain that the address was indeed produced by the SHA256 RIPEMD160 process. I would think mathematically there is some way to do this without revealing what it was you hashed. I mean, you can verify that you are who you say you are simply by using your private key to sign a message; I would think a comparable process would work for this. EDIT: Facepalm; you're hashing the public key. You don't need to hide that. See my comment below.

gizmo686 13y ago
Two points. First, crypto is hard. Unless a system is proven to have a certain property, assume the worst case scenario for your system. Second, SHA256, RIPEMD160 are hashes. By definition (of an ideal hashing algorithm), every output can be generated with the same probability, and changing a single bit of the input will have a 50% chance of changing a given output bit.
- Xcelerate 13y ago
  I am familiar with how hashes work (I've written a Bitcoin address generator myself). To illustrate what I mean: The Bitcoin address is just some chain of hashes (and a checksum) applied to the public key. To prove that the address IS actually output from the hash functions [and not spam], simply provide the public key along with it. Of course, you might say that is way too much data for the blockchain to handle. So you only limit the requirement of providing the public key to "suspicious" transactions. What constitutes a suspicious transaction could be a matter of debate, but I imagine it could be done, and it would avoid the problem of a Bitcoin's value depending on its ancestry.
  - drivebyacct2 13y ago
    Yeah, I think there is actually WIP to do something along the lines of what you worked out. However, I'm not sure what good identifying "suspicious transactions" is going to do. They're not reversible. You can't really make any attempt to "blacklist" them - you'll almost surely lose.

rockyleal 13y ago

I think there is a lot of sensationalism in the way this issue has been aproached. To inject data into the blockchain in this way is comparable (although not identical) to writing the same 'evil urls' in a dollar bill with a pen, and then passing it around. It is a problem that exists in a different layer than the currency, even if it is to some degree 'passed on' through the currency. Likewise, the solution (imho) lies in a different layer: detect a cp link in the blockchain? Great, take down the link, problem solved. Just as it is not the fault of TCP/IP, or its 'downfall', that it is able to transmit 'evil data', it is not Bitcoin's fault what vandals sometimes write on it.

daveasdf 13y ago
While you likely have a point that this is being sensationalised, the money analogy isn't quite accurate. The problem is that such "evil" messages can be broadcast globally without the ability to remove them. A dollar bill with a message on it can be taken out of circulation; the bitcoin blockchain can't be reset without major chaos ensuing.
- new299 13y ago
  Interesting the act of marking coins with messages is not new. In Ireland coins used to get marked with political messages from the UVF and others, I believe it was quite common for a time. http://www.cointalk.com/t195082/ http://www.cointalk.com/t195082/
aneth4 13y ago
This is wrong on all points. A dollar bill is seen by an infitesimally small number of users as opposed to 100% of full bitcoin nodes. Dollar bills are also transient and easy to destroy, whereas the blockchain is permanent and forever. Finally, there is no entity that could determine unacceptable content or delete it, and if there were it would carry the standard abuse problems of any censorship program. So while the issue may or may not be sensationalized, writing ignorant and wholly incorrect commentary is not the antidote.
- 13y ago

tyre 13y ago

This will neither bring bitcoin down or change it forever. Any information contained in those bytes is just that: information. What can you say in 20 bytes that can have permanent, material damage to human beings? A wonderfully sensationalist title, but really nothing to back it up.

jerf 13y ago
"What can you say in 20 bytes that can have permanent, material damage to human beings?" The AACS encryption key was 16 bytes: http://en.wikipedia.org/wiki/AACS_encryption_key_controversy http://en.wikipedia.org/wiki/AACS_encryption_key_controversy In general, private keys are in that range of byte size.
- sneak 13y ago
  They were, indirectly, drawing attention the non-import of that particular byte sequence - it literally does not matter, and the whole thing was to illustrate that a) you can't censor tiny speech effectively and b) DRM is doomed and the keys will always be reverse-engineered. Saying something meaningful enough to get someone jailed for possessing a drive with the string on it (the criteria for this to be actually harmful to bitcoin) is nearly impossible in 20 bytes in most parts of the developed world. The article is sensationalist bullshit.
  - jerf 13y ago
    "Saying something meaningful enough to get someone jailed for possessing a drive with the string on it (the criteria for this to be actually harmful to bitcoin) is nearly impossible in 20 bytes in most parts of the developed world." In a sensible legal regime, sure. In a legal regime looking for an excuse to shut down BitCoin? Easily done. Technically the AACS key is still illegal. I think the latter rather than the former is more accurately the threat. But then, if a legal regime is looking to shut down BitCoin they already have plenty of avenues. It already looks an awful lot like money laundering, for instance. So this line of thought is garbage... but only because there's no way any legal system would have to stretch this far to attack BitCoin, because they've got a wide variety of far more plausible attacks. It's not exactly the BitCoin-friendly line of argument you might be hoping for.

scottmcleod 13y ago

Title seems irrelevant. My prediction is we will see coins dedicated to just this purpose.

abrkn 13y ago
https://bitmessage.org/ https://bitmessage.org/

ck2 13y ago

I guess they should have disallowed vowels eh? Has spam appeared yet? Because you know that is next.

spullara 13y ago
Without anyone actively looking at it, addressee spam probably won't matter. If you could send from a chosen address you might have a point though as it would show up in people's wallets.

LAMike 13y ago

What's the worst thing you can transmit with 20 bytes? A link to a website? A couple of the 7 words? A "yo mama" joke? C'mon this is a BS linkbait article

ceejayoz 13y ago
A link to child pornography, perhaps, with which law enforcement would have an excuse to make any selected bitcoin user's life a living hell.
- hobs 13y ago
  or... take down the link.
  - ceejayoz 13y ago
    Isn't the point of the article that the link is in the block chain itself?
- jasonzemos 13y ago
  A link to something isn't possession of something. Any URL might become worthless anyway once the real offending source material is removed.
  - ceejayoz 13y ago
    We live in a world where folks like Aaron Swartz get driven to suicide by overzealous prosecutors, and you don't think law enforcement could use that sort of thing as an excuse to harass you?
- sneak 13y ago
  A link to insert boogeyman here which is also on the hard disks of a few hundred thousand other people, downloaded automatically, and stored in a file with a dozen other gigs of bitcoin transaction data. Sounds like an airtight case.

moxie 13y ago

Travis Goodspeed and Dan Kaminksy demonstrated this in 2011 by embedding a tribute to the late Len Sassaman in the blockchain: http://pastebin.com/raw.php?i=BUB3dygQ http://pastebin.com/raw.php?i=BUB3dygQ

eurleif 13y ago

Kind of like how somewhere, within the digits of pi, there's all sorts of criminal data. http://everything2.com/title/Converting+Pi+to+binary%253A+Don%2527t+do+it%2521 http://everything2.com/title/Converting+Pi+to+binary%253A+Do...

tlrobinson 13y ago

This brings up some interesting questions. One could also XOR some illegal data with the text of the US Constitution, then claim that the Constitution "contains" that data, you just need to XOR it with this particular key. Obviously that's absurd, but where do you draw the line? You need specialized software and the 32 byte transaction ID in order to extract the data. What other permanent public records could be manipulated like this?

batgaijin 13y ago
That's the principle behind the OFF P2P system: http://en.wikipedia.org/wiki/Owner_free_filing_system http://en.wikipedia.org/wiki/Owner_free_filing_system US legal system is based on intent so it's kind of pointless.

AnthonyMouse 13y ago

The flaw in all of this is that you're embedding 20 bytes in the blockchain. In order to do that, you have to choose an encoding method. In order to get the embedded data back out, you have to convey the encoding method and which block is encoded with it to the recipient. Which is totally pointless because if you can convey that to the recipient then you might as well just use the same communications method to convey the original message. The only plausible reason not to would be if the law prohibits the message but not the information about how to construct the message from the blockchain (and even that is not guaranteed). Even then all you would accomplish is to cause the government to pass a new law that prohibits you from telling anyone that a prohibited link is encoded in the block in the same way that you're currently prohibited from telling anyone the link itself. The real problem here is not that child pornographers would actually use bitcoin to distribute links, it's that assholes who want to damage bitcoin would put contraband in the blockchain in order to cause legal trouble for innocent users. But I think that's a broader problem than just bitcoin. You can encode anything into anything. Take anything anyone else has posted and xor it with something you want to encode. The output will resemble garbage rather than either input. But now you can post the "garbage" and instructions on what to xor it with to allow anyone to recover your encoded message, and the poster of the other message becomes an unwilling participant in your encoding scheme. It clearly makes no sense to punish distributors of the original message just because the encoded message is contraband. Which doesn't mean there won't be laws that will punish it anyway, but that is the fight that needs to be won -- to not allow stupid laws that would punish innocent people.

new299 13y ago
The "encoding method" is ASCII text. The data can be extracted by running "strings *.dat" on the block chain on any UNIX system. After that you can grep through the output. This is not like XORing data, or as some people have said "everything occurs somewhere in the digits of pi". The blockchain in no sense encodes all possible values, or a fraction thereof, the data is trivial to extract. This is much more like, it's sitting on the webserver, but not indexed by google. It's actually even worse than that because you can still just grep through the blockchain and find what your interested in. This may or may not be a problem for bitcoin, but I think it is legally problematic at the moment. This may move us toward a world where it's not illegal to store any particular data or even distribute it. The illegal act might be the viewing or "distribution with intent" or the data. I think that would be an interesting development. Personally as a user of Bitcoin I've deleted the standard qt client, I personally don't want that data on my computer. I now use a blockchainless client (Electrum).

siculars 13y ago

Of all the things threatening bitcoin this is by far the least worrisome. What if people start writing links to censored/illegal content on circulating dollar bills? Nothing, that's what.

ema 13y ago
You can just throw away a dollar bill with illegal stuff on it. You can not throw away the data of a bitcoin transaction without throwing away all transaction which occurred later on the block chain.
hackerboos 13y ago
Bad analogy. There aren't copies of said dollar bill in the wallet/purse of everyone that uses dollar bills.

drivebyacct2 13y ago

Am I wrong in thinking that this is some sort of "freedom of speech" and that it isn't necessarily wholly different than Bitcoin's sense of "hands off, let it be, decentralization, no one can control/stifle/limit/etc"?

dasil003 13y ago

How is this any different than a government declaring bitcoin illegal for whatever legal reasoning they can come up with? It's not practical to shut down everyone with a bitcoin database any more than it's practical to raid every server with wikileaks data. If they're going to declare this nuclear war on bitcoin it's not going to be on the basis of some piece of data which by the point it's in the blockchain is out of the bag anyway.

TheEskimo 13y ago

I believe that there is an even more important practical issue. What if someone manages to embed something very much like the EICER string[0] in it? How many people do you think would use the bitcoin client on windows if their AV automatically deleted the blockchain as it downloaded in a misguided attempt to protect them? Of course, first we have to know if this is possible at all. Does anyone know if there's either a) 20 bytes with a very high AV detection rate or b) some way to embed more than 20 bytes in a row in the block chain? [0]: http://en.wikipedia.org/wiki/EICAR_test_file http://en.wikipedia.org/wiki/EICAR_test_file

oleganza 13y ago
After a couple of times when AV deletes the blockchain, it will either be uninstalled by the user, or fixed by its developer. Not a big deal.

andr3w321 13y ago

Can someone post the command to create these messages or at least tell me what portion of the transaction this is being stored under? I am curious. My chain is a bit out of date, but I was able to generate the messages http://pastebin.com/wdpF4L4k http://pastebin.com/wdpF4L4k ~/.bitcoin/blocks $ ls | xargs strings -n 20 | tee ~/Downloads/hiddenblockchain.txt https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_Calls_list https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_Calls... Are they just sending coins to an invalid address (their string)?