*Review* **Blockchain-Based Multimedia Content Protection: Review and Open Challenges**

**Amna Qureshi \* and David Megías Jiménez**

Internet Interdisciplinary Institute (IN3), Universitat Oberta de Catalunya (UOC), CYBERCAT-Center for Cybersecurity Research of Catalonia, Castelldefels (Barcelona), 08860 Catalonia, Spain; dmegias@uoc.edu **\*** Correspondence: aqureshi@uoc.edu

**Abstract:** In this paper, we provide a holistic survey of multimedia content protection applications in which blockchain technology is being used. A taxonomy is developed to classify these applications with reference to the technical aspects of blockchain technology, content protection techniques, namely, encryption, digital rights management, digital watermarking and fingerprinting (or transaction tracking), and performance criteria. The study of the literature reveals that there is currently no complete and systematic taxonomy dedicated to blockchain-based copyright protection applications. Moreover, the number of successfully developed blockchain-based content protection systems is very low. This points towards a research gap. To fill this gap, we propose a taxonomy that integrates technical aspects and application knowledge and can guide the researchers towards the development of blockchain-based multimedia copyright protection systems. Furthermore, the paper discusses some technical challenges and outlines future research directions.

**Keywords:** blockchain; digital watermarking; digital rights management; digital fingerprinting; cryptography
