Are There Really Unsavoury Images in the Bitcoin Blockchain?

Bad news is always good for mainstream media channels as it sells more newspapers or pulls in more viewers. Bear that in mind when you see the next blockchain article covered in the press or on television. The Guardian recently published an article online that included the following headline: “Child abuse imagery found within bitcoin’s blockchain.” If that’s wasn’t enough to boost visitors to their site, the first paragraph goes further by suggesting it could spell the end for Bitcoin.

German researchers have discovered unknown persons are using bitcoin’s blockchain to store and link to child abuse imagery, potentially putting the cryptocurrency in jeopardy.”

I thought I would take the time to check out the validity of the story and started by looking at some of the responses from blockchain experts. Andreas Antonopoulos, a world-renowned Bitcoin advocate, took to Twitter with the following tweet when the news story broke.

I know Twitter is not geared up for users to enter into detailed discussion with the rather modest maximum character limit, but I felt that was a fairly weak response considering how damaging the article could be. I was expecting a much more robust defense of blockchain technology, but maybe he was preoccupied with other things when he sent out the tweet.

Bitcoin has long been considered the domain of drug dealers and terrorists, so adding child abusers to the list looked to be very worrying. A few days later, Antonopoulos followed up with a much more detailed explanation of why this was fake news

From the research The Guardian quoted in their article, it’s clear that the reference to illicit imagery is factually incorrect. Imagery is defined as a collection of visual images, but the research paper states “The remaining instance is an image depicting mild nudity of a young woman. In an online forum, this image is claimed to show child pornography, albeit this claim cannot be verified”. From 160 Gb of blockchain data, the team was able to find just one image that they considered to depict mild nudity.

There are quite a few images contained within the blockchain including one of anti-apartheid revolutionary, Nelson Mandela. The inference from the article published by The Guardian is that the images are plain jpeg or png files that anyone could access, either accidentally or otherwise. The images are encoded with a variety of encoding systems, and all you see in the blockchain are a set of harmless hexadecimal addresses, no images at all.

This is the start of some hexadecimal addresses for part of one blockchain “image.”



If you paste this into a Hex to plain Ascii converter, it will reveal the following innocuous text.

 =ybegin line=128 size=8776 name=bit

The full list of addresses for this image can be found within a Python script on GitHub, and if you run the script, it will convert the addresses to a regular jpg file. This is not something that could be done accidentally, and there are far easier and cheaper ways for individuals to distribute illicit images than using the Bitcoin blockchain. This is the image you will see if you run the Python script.


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Financial analyst, smartphone app designer, technical writer, and crypto enthusiast. Blockchain verified graduate of MOOC 9, DFIN-511: Introduction to Digital Currencies, run by the University of Nicosia.