Bitcoin's blockchain holds child pornography content – researchers

MANILA, Philippines – Researchers at RTWH Aarchen University in Germany have found a small number of files containing child pornography images or links stored on the bitcoin blockchain. This may pose legal hurdles in possessing a copy of the bitcoin blockchain in countries where child pornography possession is illegal.

The blockchain, which acts as a digital ledger for cryptocurrency transactions, also allows the storage of small amounts of non-financial data. While this metadata within the blockchain would normally include notes on the trading of bitcoin, it can also be used to store links and files.

The study, entitled "A quantitative analysis of the impact of arbitrary blockchain content on Bitcoin", found some 1,600 files on the blockchain, of which 99% were texts or images.

The study said among those files, "there is clearly objectionable content such as links to child pornography, which is distributed to all Bitcoin participants."

Three files are specifically notable, according to the study, as "Two of them are backups of link lists to child pornography, containing 274 links to websites, 142 of which refer to Tor hidden services. The remaining instance is an image depicting mild nudity of a young woman."

As a result, having a portion of the bitcoin blockchain might be seen as illegal possession in a number of countries, including Germany, the United States, or the United Kingdom.

Blockchains need to change

In its March 20 report, The Guardian said that while spending bitcoin "does not necessarily require a copy of the blockchain to facilitate, some processes, such as some mining techniques, require the downloading of the full blockchain or chunks of it," leading to the problem of possession of child pornography in the research data.

The study's researchers meanwhile said, “Since all blockchain data is downloaded and persistently stored by users, they are liable for any objectionable content added to the blockchain by others. Consequently, it would be illegal to participate in a blockchain-based systems as soon as it contains illegal content."

The impact of this may cause problems in bitcoin's ecosystem. The researchers explained that "considering legal texts we anticipate a high potential for illegal blockchain content to jeopardize a blockchain-based system such as bitcoin in the future."

The researchers thus emphasized the need for refinements in blockchain designs to address the issue of unintended data insertion within the blockchain. – Rappler.com