Recently, I've become interested in distributed, peer-to-peer (p2p) file sharing, including BitTorrent (en.wikipedia.org/wiki/BitTorrent) and the InterPlanetary File System (ipfs.io) (IPFS). This question specifically concerns IPFS.

IPFS is very complicated for non-technical people, so I'll try and break it down for the purpose of this discussion:

In IPFS, you can add data to the global file system, which produces a "hash" (a string uniquely identifying the data) that you can share with others. Data in IPFS is content-addressed, meaning that instead of using URLs or locations for data, it uses fingerprints of the data itself. This has several useful characteristics:

  • anybody on the network with the same data can serve it to you, reducing the burden on a web server and eliminating the waste of bandwidth that is HTTP;
  • data can remain available even after the original host fails, which makes archiving data much more reliable on IPFS;
  • and there is no central system that can fail, like DNS resolvers, that can prevent the system from operating (aside from, of course, normal internet infrastructure).

When sharing on IPFS, you aren't actually sending whole files to peers; instead, these files are broken apart into "blocks" of data which are retrieved separately (and often from different peers altogether). These blocks are re-assembled at the end to form the complete data.

Now, suppose someone is sharing child pornography via IPFS. Under U.S. law, the mere possession of child pornography is illegal, so the sender is certainly acting illegally. The recipient of these files, after assembling the blocks to form the files, are now in possession of content that visually depicts minors engaging in sexual activity. However, would an intermediary node (hypothetically) that may have cached a block needed to form the violating data be guilty of possession? The block alone cannot represent the visual activity that constitutes illegal material, and in fact, the hash representing the block can represent any such block with the same data (since the hash identifies the data, not a location), so its entirely possible (if slightly improbable) that the same hash for a block used in child pornography could be a block used to represent part of a Disney movie. For example, these two sentences, broken down into uniquely identifiable chunks of two:

I have two cats in my house.
I |ha|ve| t|wo| c|at|s |in| m|y |ho|us|e.


You should burn in Hell.
Yo|u |sh|ou|ld| b|ur|n |in| H|el|l.

You'll notice that both sentences have a common chunk, "in". Under US law, would someone who possesses this block, "in", be responsible for its use in all contexts, such as in the second sentence?

Obviously, in real data these chunks are between 256 kilobytes and 2 megabytes, so the chance for collision is greatly reduced, but by design of the system, content addressing allows for the avoidance of duplicate data. My question is how that affects legal regulations concerning said data.

3 Answers 3


18 U.S. Code § 2252 defines a crime and punishment for knowingly transporting, or reproducing for distribution by any means, visual depictions involving the use of a minor engaging in sexually explicit conduct.

Here are some sample jury instructions that rephrase this and give definitions for each of these terms. Here are some others (at p. 469). This law review article discusses the knowledge requirement of this statute.

It would be an easy argument that the operators of the intermediary nodes do not have the requisite knowledge of the material flowing over their networks and computers to be implicated by section 2252, especially when they are broken down into chunks that can only be re-assembled at the destination.

United States v. Kuchinski, 469 F.3d 853 (9th Cir. 2006) is an example of a case where a defendant was found to not have the requisite knowledge of child pornography that was found in his browser's cache folders. These were complete files, no assembly required. However, the court said:

where a defendant lacks knowledge about the cache files, and concomitantly lacks access to and control over those files, it is not proper to charge him with possession and control of the child pornography images located in those files

An IPFS user has no more knowledge of the pieces being passed through their computer than this defendant did of his cache (unless of course they are the source or destination).

  • Are there any precedents on the data divided into chunks? And also, what is the legality of the actual chunk? I'm going to accept this answer for the specificity about chunks, but I am curious, could a person claim to be innocent of possessing pornography because they merely possessed chunks that, put together, could make up part of it, given that the system operates on a base unit of chunks and not files? Jan 2, 2017 at 4:06
  • my question was concerning peer-to-peer filesharing whereby a node requests blocks of data that might comprise child pornography but are not themselves. I offered two sentences as an example, where the "chunk" of data "in" is found in both sentences but the sentences have profoundly different meanings--could someone be prosecuted for possession of chunks of data that are contained both in child pornography (or other similarly illegal content) and in legal content? Jan 2, 2017 at 5:16
  • In my example, they don't necessarily know or not know whether or not the chunks are used in child pornography. Is the irrelevance of this information an indication that this could not really be prosecuted under current law? Jan 2, 2017 at 5:18
  • This question concerns the use of data chunks that are coincidentally in child pornography. For example, say I'm trying to use IPFS to peer-to-peer share a documentary I cut. One of the chunks of data comprising my documentary happens to be the same chunk used in child pornography (this is a freak accident and the content itself is completely different due to how the bytes align, but for our purposes the small chunk is similar--this chunk isn't necessarily at the same index, but it has the same identifier since it's the same data). Could a prosecution argue that constitutes child pornography? Jan 2, 2017 at 5:21
  • I see, so this is not a visual depiction on its own--the specific sequence OF the blocks would allow for the assemblage of child pornography. Does this sequence (just a list of identifiers of data, not the actual data) constitute a visual depiction? Basically, does something that allows you to put together child porn count as child porn? Jan 2, 2017 at 5:24

The provision of chapter 110 of title 18 (US Code) outlaw child-porn images, including computer images. The law doesn't further define what a "computer image" might be. Most likely, it would be interpreted as referring to a computer file intended to be displayable and which would display a pornographic image of a child. A corrupted porn file (which doesn't display at all) would probably be still considered to be a computer image. A file that was 75% of a pornographic image would likely also be so considered. There isn't a statutory threshold, rather this is a question of when the jury would be convinced that the file is a child porn image. If there's a 50-50 chance that the file (reconstructed, somehow) just coincidentally resembles a child porn image, that should yield an acquittal. If there's a 95% chance that the file really is a porn image, that would probably yield conviction.

  • So these files are broken up into chunks, like above. Does the court examine each individual chunk for the above threshold or some arbitrary combination of them? How do courts account for indexes of content addresses (a file not pointing to other files but containing the necessary information to identify those other files)? For example, if 200 blocks are necessary to form a pornographic image, and the hash that the originator is distributing identifies a file containing the hashes for all 200 blocks necessary to form a pornographic image, is that file considered? Jan 2, 2017 at 2:25
  • Essentially, what do they mean by "file?" Do they mean the assemblage of all of the blocks necessary to form the pornographic file, or do they mean each individual block? Jan 2, 2017 at 2:26
  • To be clear, this is a good answer for normal file sharing, but I was looking for the legality of individual chunks and how the court would evaluate them. Jan 2, 2017 at 3:13

ISP's servers can run a "hash value and photo DNA signature analysis on all of the files on their servers and any image signature that match they report to the National Center for Missing and Exploited Children (NCMEC). According to the U.S. Justice Dept.(DOJ) any image including over age models that appear to be under 18 can be prosecuted, even clothed children or anything they say is CP and you can be arrested. They come around 5am screaming "child pornography, search warrant, over and over. You open the door and you are automatically pushed backward with a 9mm gun in your face followed by two four others two with long guns that look like band rifles and so do the guys holding them look like high school marching band members. Others are carrying Encase forensic units to scan your hard drive for images that match known CP hash values, including search words. Take for example you had searched, "two boy fighting" what law enforcement does is take take the words "two boys" and say it is INTENT.

CP is exempt from Freedom of Information FOIFOI reporting made that way by people in power who can only maintain their power through the conventions of secrecy; people have no idea that they are destined for judicial entrapment, extortion, exploitation, and total loss.

This lays CP investigations wide open for abuse because there is little or no DOJ oversight of the billions of dollars spent by the U.S. Department of Homeland Security that is funding the CP witch hunt via NCMEC and the mass media is almost completely silent in favor of giving their readers the vicarious pleasure they get from reading daily CP stories in the media and watching the arrests on TV. By creating fictitious enemies dark government agencies working in the background have increased their budget and powers 10 fold over the past two years to arrest and interrogate citizens. CP is the main card played by the enemies of privacy and freedom of speech in order to bring down websites, filter the internet, question people, implement personal restrictions on citizens and other stomping on civil liberties with total impunity. By playing the CP card it is possible to curtail all kind of freedoms without any opposition because it is about "the children" who have become law enforcement objective correlative because of the guaranteed automatic emotion it elicits. Across the nation good men and good fathers are waking up to the highly published national epidemic of pedophilia, CP, and sex trafficking involving federal and state government and the horrors of a criminal court system unwilling to look after their constitutional protections by making it almost impossible for an affirmative defense.

  • While very interesting, this does not directly answer the question. I'd love to see an editorial about this in the New York Times, but it's not news to me that governments hype up threats (like terror) to legitimize power-grabs and monopolies (military-industrial complex). Jan 2, 2017 at 17:43
  • Also, how can they run a hash value and photo DNA signature if the data in question is not a photo itself, but merely a part of the data making up one? I s'pose, given enough resources and enough lax privacy laws, such analysis is technically possible, but I don't think that is something ISPs do, especially given that it costs money and they have no real incentive to do so, and it pushes a big brother narrative they would rather avoid. Jan 2, 2017 at 17:46

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