Bitcoin Forum

Over the last weeks I managed to use steganographic methods to store custom data in the block chain. The only required information to retrieve the data is the starting block number and information about the algorithm that was used to store the data.

This data contains information that is considered illegal in most Western countries. In fact, most countries are likely to send you to jail, if you knowingly spread this data. Which is exactly what you're doing right now - if you're running a Bitcoin client.

Please consider this as a warning. In exactly one week from now I will inform US police departments about the way how the data can be retrieved from the block chain and how IP addresses of nodes distributing this data can be collected. I can't tell you what to do, but by running a Bitcoin client right now you're in legal jeopardy.

Over the last few weeks I managed to use steg-trolling methods to store custom data in the block chain. The only required information to retrieve the data is the starting troll post number and information about the algorithm that was used in my parents basement to store the data.

This data contains information in my diary of trolling. In fact, most countries are likely to do absolutely nothing, as I'm a troll, if you knowingly spread this data. Which is exactly what you're doing right now - reading a parody of a lame troll post.

Please consider this as a warning about the troll's intelligence. In exactly one week from now he'll inform his parents that at the ripe age of 40, he'll finally move out. I can't tell you what to do, but by reading this post at least you'll get a cheap laugh from some silly fool trying to spread fear, uncertainty and doubt.

Choke on my bitcoins, you silly troll.

+1 :p

+2

Funny indeed!

*yawn* printed this information and loaded it onto the wayne train heading to Mt. Whateverest...

Over the last few minutes I managed to use xor substation methods to store custom data in the op post. The only required information to retrieve the data is the accompanying xor data set and information about the algorithm that was used to store the data.

This data contains information that is considered illegal in most Western countries. In fact, most countries are likely to send you to jail, if you knowingly spread this data. Which is exactly what you're doing right now - because you read op's message.

Please consider this as a warning. In exactly one week from now I will inform US police departments about the way how the data can be retrieved from the op's message. I can't tell you what to do, but by reading the op's message you're in legal jeopardy.

So we can all agree that this guy is trollin' hard, but this sort of thing has been discussed a little previously




Are end users, in fact, liable for data they unknowingly transmit?  Discuss.

At least in Germany to charge someone with a felony it requires a premeditation. As I only intent to spread the blockchain in order to transmit BTC there is no crime. Dunno what western countries he is talking about but it is more or less like jailing the house owner after someone painted something illegal onto his frontage. I hope this is impossible in other countries as well. Furthermore the thread owner already made a confession to own and spread illegal content. If he's tellling the truth (and I really doubt it) I hope he is not that dumb to tell the police as it is more likely that they detain him.

I work in a large US software company which deals with UGC (user generated content).

Illegal content is serious shit. We have systems which MOVE the illegal data when we find it to non-production machines. We are also required to notify the authorities. The authorities come and potentially REMOVE THE HARD DRIVES with the illegal data. If we don't move the data off the production machines, they have the authority to shut them down and/or seize them.

Not removing illegal content that you are aware of is very serious.

I this guy thick or what? In one week HE will inform US police departments about illegal data HE put in the block chain? Orly?

In the US you must also have intent when transmitting the data.  The court must show that actions you took had the intent to distribute (transmit) something that is illegal.

I've worked on the forensic legal side of this stuff in the past.

Quite simply any collection of 1's and 0's can be made into something illegal given the correct, "algorithm."  So given the right additional data the bitcoin logo could be a harbinger of illegal content!

The important question to ask is, did the person, knowingly and willing, transmit digital content of an illegal nature.

So far the only person here that is doing theoretical illegal activity is the OP.  Did the admins get his ip addr?


Dear diary, today OP was a massive....

EDIT: This is a reply to gigis post:

You are talking about take down notices. IMHO this is not applicable here as I can not remove the content. You need to balance the legally protected interests. What has more legal worth? Some illegal content or an entire blockchain?

Doing a little more thinking on the nature of a situation like this.

you'd have to isolate the exact segment of data and perform whatever algorithms are needed to view it...in that way, let's say someone made an illegal representation out of lego blocks, then dismantled the representation, and kept the instructions for how to recreate said image, and then sold the kit of legos...by the logic our troll friend used, the recipient of said lego kit would be guilty of sharing illegal content, as the contents could be reconstructed into an illegal image  The end user does not posess the knowledge to recreate the content, and even if they did, it seems like this extra step of obfuscation would be incredibly useful in legal matters. (I don't even know how to y-enc etc etc).  Then again...I don't know shit.

edit* OR

A graffiti artist tags a wall with an illegal representation.  A security camera across the alley is pointed at the wall, and is subsequently transmitting said image.  Surely the users of the security system couldn't be targetted. etc etc

@nodemaster: No, I'm not talking about copyright infringement, but of illegal content (ie: which you are not legally allowed to have possession of).

Situation 1: You are a web-hosting firm. One day, somebody notifies you that one of the files that is hosted on your servers is actually an encrypted file which can be decrypted using BestCrypt with the password "nasty" and if you do that you will get access to illegal content. Are you required to check, notify the authorities and delete the file? The mail in which you were informed is equivalent with clicking Report Abuse on Youtube - you are required to investigate to avoid legal problems.

Situation 2: You are hosting an ISO image of some Linux distribution. Like someone said here, using a large enough XOR key you can make that into anything. The relevant question is where exactly is the illegal content - in the ISO file or in the application with the XOR key? If you can prove that the illegal question is in the ISO file, that ISO file is illegal and must be deleted.

The fact that you have to go through a process to access the content (download Bitcoin blocks, run this software using this password) is not relevant. Think about this: everybody would be doing this if you could get away with this. Illegal content stored on secret Internet sites with complicated access protocols (port knocking) and multiple layers of encryption is still illegal.

To the previous post: no, your code is illegal if contains a XOR pattern (or something else) which is actually an encoded representation of illegal information.

EDIT: Don't forget that forensics/cryptography experts can be brought in to determine exactly where the illegal content is. The judge doesn't need to understand cryptography.

I have created an algorithm that counts by one and hidden it in the block chain. As 4+4 = 8 and 2 + 2 + 2 + 2 = 8 as well, you can see that my algorithm is merely a compression technique equal to all potential numbers. As child pornography and copyright protected data are merely numbers, if you run Bitcoin you have accessed not only all known child porn ever created up to this date, but you have also accessed child porn that has not yet been created making you a futuristic time traveling pedophile as well as a serious pirate. As you also have compressed child porn that will never be created in this universe, you are a wanted pedophile through out the multiverse!!!

This is my favorite one:

Given a large enough computation of pi there is any possible data structure (even illegal content).

Plausible deniability. If you really think illegal content stored in the blockchain is an issue for the network, you should check freenet (http://en.wikipedia.org/wiki/Freenet).
There is illegal content on freenet. After all, it is primarily designed to store content, unlike Bitcoin's blockchain.
Like the blockchain though, this content cannot be removed. It's decentralized, redundant, encrypted… Live with it.

You're also responsible for plagarism, identity theft, credit card fraud, access to state secrets such as nuclear launch codes, reading your neighbors mail, Conspiracy and treasonous plans for mass murder, expressed intent and detailed plans to produce nuclear devices, etc.

Youre reporting bitcoin to the cyber police and the consequences will never be the sane ?

DON'T WORRY GUYS, THE BLOCKCHAIN.  WE CAN BACKTRACE IT!

you do know that you get convicted if some website loads some child porn in some invisible iframe without you knowing if the cops can find it in your browser cache? Or, to take it somewhere offline, that you get convicted if you buy something off ebay and when you try to register it to your name and it happens to come out that it was stolen.

You do know that you're replying to an ancient troll topic right?

You do know that in most jurisdictions, receiving stolen property requires the keyword: "knowingly"?

You do know that if it's hidden in the blockchain with steganography, one would probably have to deliberately possess the keys and tools to extract it in order to be found culpable?

You do know that if you do get arrested for CP in an iframe and you do get convicted of it, it's only because of backwoods prosecutors and judges, and that your defense attorney isn't worth whatever the public is paying him? (I say public, because if you hired some asshole to defend you and he doesn't know enough to get you off, well then I don't know what to tell you)

Finally, you do know that I'm not a lawyer and that legal advice off the internet is worth less than what you pay for it? ;)

- Person A gives Person B AIDS intentionally
- Person B has no idea they have contracted AIDS. Person B goes out for another night of fun and picks up person C while at a bar
- Person B and person C end up having sex at person B's house. Person C and person B now both have AIDS, while person A is laughing (but also crying due to his/her own AIDS)
- Cops arrest and brutally rape person A for being in the wrong.
- Person B and person C get off scott free, minus the AIDS.

I have to say that this topic is FUD at it's finest.  Am I right boys?

Some people....

I guess he was hoping that some news site would catch wind of this topic before we completely borked it.

Troll bumpery :D.

IF YOU'RE DOING ANYTHING ILLEGAL WITH BITCOINS, THESE TRANSACTIONS/UPLOADS CAN BE TRACED BACK TO YOU!

IF YOU'RE NOT DOING ANYTHING ILLEGAL WITH YOUR BITCOINS THEN YOU HAVE NOTHING TO WORRY ABOUT.

OP: Are you the one responsible for these?
http://blockexplorer.com/address/1MaZAHzEFfinRJ2dwK6YtNDfvWMBkiAxDr

I Lol'd  :D

The XOR example makes no sense -- the entire point of a feistel transformation is that the data is now in neither part.  Using your logic, I could put an illegal file in any other file.
1. Let X = illegal file
2. Let Y = linux iso
3. Publish Y and (X xor Y)

Is the illegal content in Y or X xor Y?

To make the example more clear:
1. Let X = illegal file
2. Let Y = completely random bitstring of same length as X
3. Let Z = X xor Y
4. Post Y on one server, say a google blog.  Post Z on another, say a wordpress blog.

Now observe the following: Y is a totally random string, so clearly it contains no information about X.  What about Z?  Well think about it: if I take some fixed string X and XOR it with a totally random string, what do I get?  I get another totally random string.  So Z is also a totally random string, containing no information about X either.

So now we have two servers both storing totally random strings.  Clearly, neither is illegal alone.  But their XOR is illegal.  Who commited a crime, other than the uploader?


(Note I'm going to hope you're somewhat intelligent and can see that Z is in fact no different from Y, and does not contain "more information" about X because I defined Z = X xor Y.  If you can't see this, imagine the police arrested both the server operators holding Y and Z.  The operator holding Y will claim "but I'm just holding a random string Y, the OTHER guy is holding X xor Y".  The operator holding Z will claim "no he's lying! I am actually holding the Y part, and the OTHER guy is holding the Z = X xor Y part!"  Clearly, there is no way to tell who is lying (even the operators themselves do not know who is lying) because in fact the uploader could actually have done things either way: he could have picked Z as his random string Y' and set Z' = X xor Y' = Y)

NEW MEME ALERT, NEW MEME ALERT

SEND IN THE CYBERPOLICE!!

If i'm not mistaken, in England you could be arrested under kiddy porn laws if people other than you on a MMO wearing avatars that could be interpreted as being underage position their avatars in such a way that can be considered "inappropriate" in front of your camera...

OP, so what ! theres nothing which stops you doing exactly that with any part of the internet that allows user submission, like blog comments, forums, pastebins, email servers, and bit-torrent


STFU !!  ::)

It will be fun when there are enough blocks in the block chain for us to be able to just specify a blocknumber and offset to direct people to any "illegal" number we want.

Someone should write a program that interprets random chunks of the blockchain as bitmap data, and see what pops out.


GO!

I put InterPORNS in the Block Chain and I'ma tell yo Momma yous a Pernografer! 

arrest me, bro.

Someone give this man a bitcoin, I would, but I'm a poor student.

Some of the posters on here are dolts. Go look up mens rea then come back and talk about illegal content.

Oh ya ignorance of a foreign law is an excuse as well.

I thought we had a newbie section for newbies... How did this guy get in here?

(.)Y(.)   <----  My password. 

I'm storing pron on every website I log into!

edit: oh dam...now everyone knows my password....

How are you going to prove your own 'ignorance'?  Prove the non-existence of your knowledge.  Good luck with that.

All it takes is some prosecutor who thinks he can convincingly prove that you did 'know' to cause a lot of trouble for you (even if you ultimately win).

In most countries prosecutor must prove that you was acting illegally (i.e. knew that property was stolen). This is almost impossible, so it is very, very rare when reseller of stolen goods get imprisoned.

There is flea market in Riga, anyone knows that vast majority of goods selling there are stolen (auto radios, cell phones, bicycles etc.). But I can't mention even one person who was imprisoned for this activity. Police regularly make raids, but just confiscate items that legitimate owner described or told serial number.

Does either of them have a purpose other than being able to be recombined to reconstruct the original illegal file? If not, what's to stop the courts from ordering both to be removed? (Obviously if one of them does have a purpose other than being able to be used to reconstruct the illegal file, the other one must contain the information about said illegal file; due to the way the two files have to be constructed it's impossible for both of them to have been created for another purpose.)

They could both have another purpose.

Let P = Public domain file 1
Let Q = Public domain file 2
Let R = Y xor P
Let S = Z xor Q

Host R and S on other separate websites.


Now we have the situation where Y and Z have a legitimate purpose, since...

Y xor R produces P
Z xor S produces Q

This sounds like the Bible Code. If you take a large pseudo-random data source, apply thousands of analysis functions over it, and apply a liberal dose of interpretation to the results, you'll undoubtedly end up with "meaningful data". It's like Rorschach blobs.

I suspect if you make images out of the block chain data, you'll probably find at least 4 or 5 vaguely plausible pictures. The problem is finding them amongst the 10 million random noise pictures.

And in the meantime, You get a nice screensaver with random colors and shapes

To OP,
Please remove the word 'Thai' from your name.
It is a disgrace to my country.

Wait a minute man.How can you be so damn sure that blockchains can hold 'illegal' content that can throw me in jail?I don't understand much about cryptography or code cracking but what ind of 'illegal' data are we talking about here.The odd stray bits? or something bigger than that?

I'd love to know how UK law handles this as Im based in UK.If anyone knows please tell me.

I've got these questions for you:
1.how do you find or 'sniff' the 'illegal' data from a block chain?
2.How can running a BTC client (or miner) cause legal issues for me?
3.Is this a big problem?or something I can ignore (for a bit)?
4.What legal issues can this cause me? and can they be serious?
5.How can law enforcement and the like reconstruct the file,trace it back to you and throw u in da slammer?

Thanks

I guess the easiest way is to encode data in the amounts or in the addresses.  The amounts would cost more, but the addresses would cost more cpu.  Either way it is only an intellectual exercise

It can't

It's irrelevant, OP is only a troll, or completely delusional if he actually means this as a threat

None

If they know how data is encoded, it can be decoded. 

You're welcome

Thanx 4 the gr8 reply gnaget.Saved me a lot of worry.and yes I find that trolls are really annoying.They spread crap (info) everywhere and they confuse people (like me as well).Then they wonder why we get so pissed off with them.(Serves them right too)

Only in unsafe sites; sites that do it right don't store your password, they store a salted hash.

They don't wonder why people get pissed at them, they know it; it's because they made them get pissed at them, that is their goal from the start...

Criminal justice: You're doing it wrong.

This thread reminds me of http://www.angio.net/pi/piquery

Consider this situation:
Person A decides to sell off his old hard drive. Before he sells it, he makes some "random" data by making a disk image the size of the drive full of kiddie porn and then encrypts it with 20 minutes of 'cat /dev/urandom'. After this he then uses 'dd' to copy the raw encrypted data to the drive, effectively wiping his data (assuming the new owner knows nothing beyond foremost, but if he didn't feel secure, he could just do this multiple times with different keys) in the process. Lets also say he only had a 10gb collection of kiddie porn, so he just repeated it 8 times (assuming an 80gb drive). Person A then sells this drive to person B. After only putting 15gb or so on the drive, person B, not knowing deleted files can be recovered easily, just reinstalls windows (using quick format to boot!), and sells the drive to person C, unknowingly having distributed 6 good copies of person A's kiddie porn collection. Then, person C having been a friend to person A, and knowing the key, reports person C for possession and distribution of kiddie porn. Do we charge person B with possession and distribution? Probably not, but in the off chance we do we also have to charge person c, it would be like charging some one with dealing because there was cocaine residue on there dollar bill that they exchanged for bitcoins. If they do charge them, will they case get past a jury? Hell no, there is something called a reasonable doubt that he knew that he was selling the kiddie porn with the drive.

It is pretty much the same thing here folks.

You lost me here. Isn't /dev/urandom a one-way function?

I recently bought a 500GB hard-drive used. Spent 25 hours overwriting it with /dev/urandom (CPU bound). I then spent 5 hours overwriting with /dev/zero (I/O Bound).

Without the "Key" you can't prove whether something is data or meaningless noise.

The issue is not just storing it unknowingly; for that, it would seem extremely unlikely one could be prosecuted(but IANAL not legal advice etc).  The problem is if you are told you are storing it, you now know it and must delete it.  But it is completely unreasonable to erase bitcoin history, because it is needed for verification.

In other words, this problem won't arise in other contexts because you either don't know about it, or have deleted it.  But here, even if we are told about it, we can't delete it or the whole network breaks.
 
One solution is txs can be blacklisted as bad: nodes won't store them anymore and just reject all TX spending them.  But this will fork the chain.

It might be worth asking EFF about this.

I agree with hashcoin, this is an incredibly useful thought experiment and a brilliant attack on the Bitcoin system itself.

So let's ignore the trolly context and get down to the technical details of the attack: Is it possible to encode a small, encrypted jpeg thumbnail in the block chain without mining the block yourself? If so Bitcoin is vulnerable to your run-of-the-mill troll and this should be addressed.

If it's not possible to do unless you actually mined the block, what's from stopping some serious adversary from encoding encrypted child porn into blocks and then releasing the key later on?

What should we do if this happens?

This would open the door to double-spend attacks though.  Pay someone in bitcoins, whilist including the transaction in an illegally encoded data stream, then when you release the key to said illegal content, the transaction is reversed, and you get your coins back.

I don't see any solution to this problem, yet.

If someone printed kiddyporn in a 100 dollars bill and you got paid with it, do you need to burn your money?

It's a source of pseudorandom numbers which are a function of the state of your machine. Actually, absolutely everything a deterministic computer does is a function of it's state, hence it don't have much sense to say /dev/urandom is a function.

I meant using a chunk of output from /dev/urandom of the same size as the yet-to-be-encrypted files as the encryption key. And the point is, even if person B checked, it would look like someone used a DBAN disk on it. And the point of the /dev/urandom output as a key is that it would extremely secure, yet person C would presumably have the key, because Person A planed this with malicious intent.

Note: If you put anything on currency and try to use it, then it is defaced. You should not accept his money, because he invalidated it by printing something on it. I know I ruin your point by saying this.


This. And im pretty sure, due to the method it gets the numbers, it is completely random. It does use environmental noise.

how do others handle this? you can always generate illegal content where numbers are involved. a bank would also not rearrange transactions just because they represent evil data although that evil data would end up at the recipient of the payments and stay stored at the bank.

The output of /dev/urandom is typically non-deterministic. It's a function of the entropy pool's state, but that state itself is non-deterministic.

Entropy sources include the clock skew between the CPU's clock source and the network interface's clock source. This is dependent on microscopic zone temperature variations in the quartz crystals which is believed to be truly random. Another source is the timing of data arriving from the hard disk measured by the CPU instruction cycle counter. This is affected by turbulent boundary shear between the hard drive surface and the air around it. This is also believed to be truly random.

Real-world computers are not deterministic computers.

Isn't a note still valid if the defacement compromises less than a certain percentage of the note? I see all sorts of dirty notes in circulation, coffee stains, tears, and even plain aging in general; just print using a UV lasers (accelerating aging selectively) or putting coffee inside the printer's ink cartridge.

I thought that part of HDDs were evacuated to reduce friction...

I think the law says something along the line of if it makes it unfit to reissue. Printing CP on it in any manner would do this.

No, the heads ride on a cushion of air. It it dust that is removed from the cavity. Dust can cause enough turbulence to cause the heads to crash into the disk surface.

These days, hard-drives auto-park the heads when the power is removed. Hard drives I have taken apart also have dust traps with filters near the edge of the platters.

A little off-topic though.

cat /dev/null > thisthread

+1

Try that with a test file. It will exit immediately without writing anything.

So close, and yet... so very, very far away.

Okay, went and tested it: the '>' command overwrites the file; data or not.

You would use the append command ('>>')to avoid overwriting the file.

I was thinking maybe it was a meta suggestion: exit the thread without writing to it :)

Right, I'm about to correct my comment.

However, aren't hard disks sealed to partial vacuum?.

Actually I believe it was a geeky suggestion to blank this entire thread and nothing of value would be lost.

I suppose there may exist some hard disks designed to operate in a partial vacuum, but those would not include cheap consumer disks. The top plate is too thin to hold a substantial vacuum. I have seen some disks with vent holes you are not supposed to cover.

Specifically the Western Digital WD1600AAJB. Maximum operating altitude: 10,000 feet (3,050m) (using WD1600AB specifications)

Aren't the vents for the circuits and perhaps the motor coils?

I'm pretty sure the police are busy with other things..you know like murders and stuff. The police don't even know what Bitcoins is..and they probably don't care.

Hmmm, evil plan fail breakdown:

1. too many miners, MUST LOWER MINER COUNT!

2. think up stupid but seemingly clever plan to get miners to stop

3. implement plan on teh forumz, oh teh horrorz

4. FAIL to realize that most bitcoin miners are extremely smart.

PLAN FAIL!

My guess: Air bearings (http://en.wikipedia.org/wiki/Fluid_bearing#Air_bearings)

I don't recall criminal justice being one of my aims.

Has any of the developers commented on this issue? It sounds like this could potentially be a big problem that could criminalize every bitcoin user.

If I understand it correctly:
1. someone can store some illegal data into bitcoin (copyrighted content, child porn ...)
2. he lets everyone know what they are distributing/storing
3. if you continue to use bitcoin you can be charged for distributing/possessing illegal content

Could someone with more knowledge about this issue please add some info to:
https://en.bitcoin.it/wiki/Weaknesses

I don't agree that it is a weakness.  Webster's English Dictionary could be illegal encrypted content, if you have the right algorithm.  Any string of bits can be re-structured to be something its not by running it through the right hashing algo.   In this case the hashing algorithm itself that turns Webster's Dictionary into something else would be the illegal content, not Webster's Dictionary.


also,

This is not a security weakness so should not be on that page.

I was under impression it is possible to embed completely custom text into the blockchain:
https://en.bitcoin.it/wiki/Incidents#ASCII_embedding_into_blockchain

Is this possible or not?

If it is what prevents someone from embedding illegal content?

Hard drive heads float on an air cushion of laminar boundary flow above the spinning platter. While the drive is assembled in a meticulously clean environment (since the heads float closer to the disk surface than than the size of a smoke particle), there is a filtered vent hole so the drive can equalize pressure with the outside. This is why the drive listed above has a maximum operating altitude - with no air pressure, there is no air cushion, and the heads tear into the disk surface.

Since this isn't a hard drive thread, but rather an undying troll thread, I will point out that I can have a one-time pad that decrypts the block chain into kiddie porn. I suppose it would be up to you to decide if it is the block chain or the one-time pad that is the actual porn.

It happened, so it is definitely possible.

Embedding some really WRONG political, religious, porn etc. content into the blockchain forever might be real problem, IMHO.

This it the kind of "news" all journalist believe to understand and will spread it heavily. Do we need another bad impact on Bitcoin in news?

For most people, if they are told "there is child porn inside Bitcoin blockchain", they will get negative attitude against it. They will not care if the blockchain is normally not viewable nor that that "porn" is funny ASCII art made of dots and stars. Actually, in Canada, they might arrest you immediately ;-)  http://www.comicbookresources.com/?page=article&id=32958 (http://www.comicbookresources.com/?page=article&id=32958).

Nothing (read this thread, it might help)

How large can a continuous custom block of content that can be embedded in to the blockchain be?

Added:
https://en.bitcoin.it/wiki/Weaknesses#Illegal_content_in_the_block_chain

I think it will be a problem in the future, though probably not too severe.

20 bytes, AFAIK (one address). You can embed larger blocks (up to 512?) using OP_NOP but I don't think those are accepted by the standard client at the moment.

See also the Len Sassaman ASCII art, it's width is 20:

http://pastebin.com/raw.php?i=BUB3dygQ

Theymos great entry. Thank you for providing so much useful info.

You can have up to 520 bytes of contiguous data, and you can fill an entire block with data only slightly broken by opcodes. These transactions are accepted if they are received in a block -- they are just not relayed.

you know we could get bitcoin down to 2USD today, if we wanted too. xD

we could use this, and it would stay @ 2 for probably the duration of it's usage and existence.

This has been discussed quite a few times before, which may be why not many developers have commented.

Theymos' entry is incomplete, so I extended it. There's another situation in which it's safe to delete transaction data: if you can prove it'll never be used. The transactions that embedded flags, ASCII Bernanke etc could be deleted without risk because the chances of finding a private key that hashes to a line of English text is extremely remote. What's more, transactions with non-random looking hashes or pubkeys can be automatically identified.

Data can also be included in tx input scripts. However data blocks there don't have any effect on anything, ie, with the right database structure you can record the original hash of the transaction, then delete the unneeded data blocks if they have no effect on the connected output script.

If you encrypt the data before putting it into the block chain, the bad transactions probably can't be reliably identified. However they also shouldn't pose any legal threats to the miners. If the key is publically revealed, the same as above applies - the outputs can be removed without risk.

In short, this "attack" is unlikely to be anything more than an inconvenience. Judges would certainly frown on attempts to game the legal system like this, it'd just be a waste of court time, and might be considered entrapment.

Why is everyone so freaked out about this?

How is it any different than UPS or the post office delivering heroin and cocaine to people through silk road? It's not the deliverer who gets arrested. It's the guy who introduces the shit, or the guy who receives the shit. I've been runnin my client for a few months straight now, and I've never seen a hint of kiddy porn pop-up on my screen from the blockchain and I'm sure as hell not going to look for it. As far as I know, it's not even there rendering me safe from any legal allegations.

OP is trying to overwhelm authorities so that the FBI will get off his ass.

Doesn't changing the block result in invalidating Merkle root of that block, invalidating the block and the rest of block chain?

Or you meant that the miner may choose to skip the bogus transactions prior to mining the hash for given block? How? Setting a strict rules on his bitcoind? Still, some data may escape and become permanent.

True, but it's not too difficult for the attacker to insert arbitrary data with OP_DROP and have Eligius or some other tolerant miner include it into a block. Then the arbitrary data is spendable and can't be forgotten.


I'm not so sure about this. Courts are used to being able to order service providers to remove illegal material, but with Bitcoin this is uniquely a technical impossibility. They might not understand. And it would be easy to get an emotional response out of average people: "Breaking news: Bitcoin banks refuse to delete child porn."

The protocol would need to be changed so a node can provide partial blocks. That's the point of the merkle tree structure, the pruning aspect was just never implemented.

In the case where an output both contains arbitrary data and is also spendable, you do indeed need to get >50% of the mining power to delete the transaction.

I think it'd be easy to make an analogy to a judge. If you publish a full page ad in the New York times containing some obfuscated or encrypted illegal material, that doesn't make the NYT, the printing company or people who bought the paper guilty of a crime. Now, the court of public opinion on the other hand ....

Putting illegal content in the block chain and announcing it as an attempt to undermine Bitcoin seems like a good way to get yourself arrested.  Much better than tweeting about exploits (http://www.zdnet.com/blog/btl/scotland-yard-battles-lulzsec-anonymous-on-twitter/54207).

You'll have both law enforcement and techies trying to track you down, and given that people are already deploying de-anonymizing tools (http://www.slideshare.net/dakami/black-ops-of-tcpip-2011-black-hat-usa-2011) it seems pretty darn likely that you'd get caught.

Gavin I think you're missing the point of this thread: we are certainly not advocating people do this, nor trying to protect people who do.  Rather we are trying to figure out a way to protect innocent users from a bad person who does this while maintaining the integrity of the blockchain/ledger.

I still think it would be nice to know what exactly the protocol would be if this happens.  Again, the semi-unique thing about bitcoin is that the data could be injected in a way that you can't reasonably remove it.  In most other contexts, upon being notified of such data's existence we could just delete it and be on our way.

Mike mentioned one could prune these things if it they were known, but it's conceivable that data could be stored in a way that would still enable coins to be spent (using OP_DROP, or just using low order bits etc).

My concern is that in this instance one could end up knowingly being in possession of bad things.

Just as an observation, OP was 2 June and now it's August - what happened to the police bust after one week?  Are we still waiting, or did the OP get jailed for some attempted framing.

RE: protecting an innocent person:  any lawyers here?

I have trouble believing that you could get into legal trouble for having illegal incidental data from legitimate activities on your computer. If you can, then we're all in trouble, because it is very easy to put illegal data in your web browser's cache (JPEG and other image file formats let you store arbitrary, not-normally-shown metadata, for example). I don't think it would be hard to convince a jury that the block-chain is like your web browser's cache-- full of lots of incidental stuff that is needed for the system to work, but doesn't have anything to do with you.  Now if you happen to have one of the private keys involved in the illegal transactions, THEN you should go directly to jail....

Adding code to "shun" certain spend-able transactions wouldn't be hard, although I think that's a bad idea for the same reason it is a bad idea to respond to trolls on forums-- you'd just encourage the bad guys by drawing attention to their misbehavior.

IF (big if) somebody managed to insert a noticable amount of real child porn in such a way that a simple one line command could extract it, waits for it to be really deep in the chain before announcing it to the public, and if this happened before the filtering and pruning mechanisms are implemented - I'd imagine we could have a problem. Or maybe embed ROT13s of phrases that are highly offensive and inflaming to lots of religious people and would likely prevent them from ever accepting bitcoin as long as they remain in the chain - say "Allah is evil and not a true god" or some such. Again in such a way that anybody could extract them with a simple command.

In such a case what could be done after the fact? Could they still be trimmed out of the chain without invaldiating the block links and the whole transaction history after they were included? Or is that impossible at this point?

I really don't think this is an issue. If Oprah opens some of her fan mail and there is child porn inside, would she get arrested and go to jail for being in possession of child pornography? What if someone turns in a paper to a professor and it has illegal things in it? It would set a dangerous precedent I think.

I don't know the answer to this, but what if someone ran a Tor node and illegal things were sent through it? Same with proxy and VPN services. I'd think that VPNs would be non-existent if this was the case.

The problem isn't that some wrong text will show up in the chain, but the fact we will not be able to remove it.

Its like your house got sprayed with a very wrong graffiti and you (as it may look for others) REFUSE to repaint it.

The generation of vanity address just remind me the possibility of embedding arbitrary file and information into the block chain, particularly, a transaction record. An attack would look like this:

Embedding arbitrary file

• Convert a file (with encryption) into a string of Base58
• Split the string into, say, 4 characters per piece
• Generate vanity addresses with the 4 characters at the beginning
• Order them in a transaction
• Send money to the address and pay some transaction fee

The information will then permanently embedded into the blockchain. The only way to solve this problem is to change the transaction record into a simple account balance periodically. Since now the ordering disappear, so you cannot extract the information anymore.

This is true, but with a major caveat: the only way to prove to someone else that the transaction data is safe to delete is to give them a copy of it, which means you need to have a copy of it. Without the ability to prove this, newcomers have to trust they aren't being lied to. I think this may open up a potential double-spending attack or possibly worse; while the nodes that had a copy of the expunged data at some point can safely mark the correct transaction outputs as spent no-one else can confirm what it spent.

(Also, if someone manages to get non-standard scripts into blocks, they can create transactions that are spendable but require you to keep a copy of arbitrary data in order to be able to validate future transactions that spend them.)

Of course, as I understand it the transaction ID is computed as the hash of the transaction, so you can no longer prove that the transaction in question has the ID you claim it has, that the block that contains it or any blocks building on that block are valid, or even that the block that contains it does actually contain it rather than some other transaction you want to maliciously replace.

Which again pretty much requires some kind of trusted central censorship body, with all the transparency problems that entails. At the very least they could maliciously render particular bitcoins unspendable, which means that someone could get a court injunction forcing them to do so.

It's a bit like Schrödinger's cat.

If I have an unopenable box and tell you there is something illegal in it, is that illegal.  You can't rove it or see it or know that it exists, therefore no harm is done.  Something embedded in a block isn't visible unless you know the key, and on simple viewing would not be illegal.

A more simple example (and quite made up) is if you apply the correct cyptographic key to this post you will get a defamatory statement (with is illegal).  Is this post therefore illegal?

Depends on the jurisdiction and what the court rules. For a defamatory statement it would be worth the risk, but would you want to take the risk of uploading child porn given the life-ruining consequences of even being accused?

I think that this is a very real risk to the current system.

I just used defamation as an example (and as you say, it depends of jurisdiction).  I was more making the point that with the correct key or filter you could make anything look like anything else.  And if you don't know it's there and can't extract it, is that criminal?

Alternatively, if you DO know it is there, is it criminal?  If anyone did embed something illegal into the blockchain, then released the decryption method to the public, then everyone would know it was there, and anyone could extract it.  But whether it is illegal to have such content in the blockchain has yet to be determined.

90% of all US bills carry traces of cocaine. Are 90% of all US currency holders potentially arrestable on charges of narcotics possession?

http://articles.cnn.com/2009-08-14/health/cocaine.traces.money_1_cocaine-dollar-bills-paper-bills?_s=PM:HEALTH (http://articles.cnn.com/2009-08-14/health/cocaine.traces.money_1_cocaine-dollar-bills-paper-bills?_s=PM:HEALTH)

If I know "something" is there, but don't know what, maybe I'm just paranoid rather than criminal.

It's like a whole lot of wiki-leak files that are available but not unlocked - someone knows the key, and someone could find the key, but just because I could access it (locked or unlocked) doesn't turn me into a criminal.  If I did access the file in a locked state, but not know it's contents, that would also be a hard point to press.  (reference receipt of stolen goods - there is a difference between knowing they are stolen or not)

Sorry, in my scenario, I meant to infer that you would also be informed of what was there.

somehow this discussion got back to "with the right key any sequence of bits can be illegal".

Guess this is pointless as it is possible for sure to get any data into the chain. Just donate x satoshi to the faucet every hour with x being the ascii value of a letter of for example the "satanic verses". 8bph is slow. 2 months per page. but who would stop you? Later you announce that transactions from this one address form the satanic verses if read in sequence of their occurrence. No way to remove. Easy to decode. No bogus one time key needed.


the other thing was: if i open a letter with child porn/get such stuff smuggled into my browser cache ... no: those are examples where you don't know of the illegal content. this thread is about what if you know it is there and know how to decode but don't want it? so the analogy with the newspaper would rather be: what if somebody gets miniature child porn into a magazine add? the answer is quite clear: the magazine would not be allowed for sales from the moment they know about it.

i still see this could be a serious problem that might require drastic measures at some point like "genesis block 2" with all the balances but without the transactions to clean up the mess and i see no way to prevent such data from getting in. in some countries judges might be relaxed about it but some might make bitcoin illegal for such illegal content in the chain.

I guess you forgot about the part of how many people now actually use the bitcoin wallet program? Somehow I don't think it's that many. And even still to go ahead and say that there is illegal content that "you" supposedly injected would be like shooting yourself in the foot. Good job troll

Did you add those classified UFO documents that I sent you?!   :o

*Wow a Necro thread* lol

It's the appropriate thread to necro considering the "kiddy porn in blockchain" drama thread that popped up last week. It would do people good to realize that their ideas have not only been thought about before, but extensively argued, and they should learn how to use the search function before posting new drama.