Abstract

Nowadays, content is increasingly in digital form and distributed in the Internet. The ease of making perfect copies of the digital content has created a need to develop a means to protect it. Digital rights management (DRM) relates to systems designed to protect the intellectual property rights of the digital content. The DRM systems try to enable a secure distribution of digital content to the users and to prevent the unauthorized copying, usage, and distribution of the content. This is usually done in practice using encryption and digital watermarking techniques.

This thesis concentrates on the problem of protecting and distributing multimedia content securely in mobile environment. The research objectives are: (1) to design an overall DRM architecture which allows an easy content distribution to the user in mobile environment; (2) to develop protection methods that can be used in mobile devices with limited computational capabilities to prevent unauthorized usage of the audio content; (3) to create methods for managing and enforcing the user’s rights and restrictions to the content usage; (4) to study a method for providing the users with an easy access to new digital content and services. The research is carried out by first developing an overall DRM platform to mobile environment. The experimental prototype of the platform is implemented on server side to PC environment and the client runs on a mobile phone. The platform is used to test the functionality and complexity of the content protection methods developed which are based on digital watermarking and encryption techniques.

The main results of the thesis are: (1) a DRM platform for mobile devices that supports peer-to-peer networking and license negotiation; (2) audio protection methods utilizing digital watermarking and encryption techniques which support content superdistribution and content preview; (3) methods for counting offline how many times content has been played on the user’s terminal using watermarking and hash chains; (4) a method for adding metadata, such as a web link, into audio content, so that it survives digital to analog to digital transformation and recording with a mobile phone.