Cybersecurity and the Blockchain: Preventing the Insertion of Child Pornography Images

Abstract

The fight against child pornography on the Internet is difficult due to the inability of controlling the dissemination of content. While the cryptocurrency applications of a blockchain, such as Bitcoin, primarily store financial data in blockchain transactions, numerous approaches to arbitrarily insert other types of data are possible, including content in the form of readable text and images. Thus, considering the blockchain principles of decentralization, immutability, censorship resistance, and net neutrality, we are suddenly presented with a set of new challenges for mitigating the storage and distribution of illicit and potentially illegal data. Such a novel cybersecurity threat requires an adequate solution within a decentralized paradigm. In stark contrast to the countermeasures proposed in literature for filtering out illicit content from other legitimate data, this study proposes the first appropriately designed solution for effectively mitigating these threats whilst maintaining fidelity to the underlying core principles of the blockchain. Through the designed approach, arbitrary images in blockchain transactions are detected, and whilst leveraging an off-chain content filtering service, successful discrimination is achieved between clean and illicit embedded data. The proposed methodology was evaluated directly on the Bitcoin blockchain, successfully demonstrating a pioneering and viable approach for thwarting the insertion of child pornography images. The presented solution within this research is made available on GitHub [1] for open-source use.