Yet another concept for blockchain technology.
Krzysztof Okupski has presented a graduation thesis from Eindhoven University of Technology, titled “(Ab)using Bitcoin for an Anti-Censorship Tool“. He describes a method for embedding messages in Bitcoin transactions so that they are published in the Bitcoin blockchain.
Okupski is is motivated by the desire to enable free speech in the face of censorship, and aims to use the Bitcoin blockchain as a global channel to “broadcast” messages.
He takes an approach akin to steganography, embedding the message into elements of the transaction so that they appear to be ordinary transactions (more or less). The purpose is to hide the messages from censors, yet have them visible to the world.
(I haven’t read his 97 page thesis, which appears to include valuable documentation of Bitcoin and related data structures and algorithms.)
First, as he admits (and his title implies), there is some question as to whether this is a good use of the Bitcoin blockchain. All the nodes in the network expend work validating all these messages, whether they want to or not. Extra work, extraneous work, “blockchain bloat”.
So maybe this is a job for sidechains or a separate cryptocurrency?
Second, it is questionable if this actually achieves his goals. While obscure (and compressed), the messages are certainly detectable by any knowledgeable user, including censors. As he acknowledges, the source is probably not anonymous unless other steps are taken to anonymize the activity (in which case you don’t need the special encoding).
This may be a lot of work to little effect.
Thirdly, he floats the notion that if authorities will have to choose either both Bitcoin and messages or neither, they must choose both because Bitcoin is so important. Given the fact that many of the “censors” are already banning Bitcoin, this argument doesn’t have much force.
But suppose this or something similar is deployed. Every Internet system that has offered unmoderated anonymous postings has collapsed under the weight of spam, flamewars, scams, theft, and pornography–not to mention commercial, terrorist and government propaganda. One has to wonder if this feature would be a good thing or not, if it crashed the blockchain and Bitcoin with it.
However, this thesis reminds us that there is little to stop the blockchain from being used for steganographic messaging, at least at at low bit rates.
- Krzysztof Okupski, (Ab)using Bitcoin for an Anti-Censorship Tool, in Department of Mathematics and Computer Science. 2014, Eindhoven University of Technology: Eindhoven. http://enetium.com/resources/Thesis.pdf
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