A personal mobile DRM manager for smartphones

Abstract

In this paper we report on our experience in building the experimental Personal Digital Rights Manager for Motorola smartphones, an industry first.

Digital Rights Management allows producers or owners of digital content to control the manner in which the content is consumed. This may range from simply preventing duplication to finer access policies such as restricting who can use the content, on what devices, and for how long. In most commercial DRM systems, the average end user plays the role of content consumer, using DRM protected content made available by a service. Here we present a personal digital rights system for mobile devices where the end user has the ability to place DRM protection and controls on his or her own personal content.

We designed the personal DRM system to allow users of a mobile device to transparently define controls and generate licenses on custom content and securely transfer them to other mobile devices. A user is able to define and restrict the intended audience and ensure expiration of the content as desired. Compatible devices automatically detect each other and exchange credentials. The personal DRM system on each device safely enforces the content usage rules and also handles moving licenses between devices while preventing leakage of content. We implemented a prototype of our system on Motorola E680i smartphones.

Introduction

Digital Rights Management (DRM) refers to a collection of technologies used to control access to digital data. It is generally used by copyright owners or publishers of digital content to specify who can access the data and in what manner. This is accomplished by specifying the rights that the user of the content has, and the restrictions on the consumption of the content.

For instance, an online movie rental service that lets users download video files to a personal computer for a certain period uses DRM protection to enforce the terms of the rental license. Thus, even though the downloaded file is on the user's computer and may be seen as being under the “user's control”, DRM is used to lock the file and essentially make it difficult to play after the expiration of the rental period.

DRM is also used in mobile devices where, driven by huge advances in network infrastructure support as well as a boom in the number of interconnected personal devices, the modern mobile customer experience has become increasingly compelling. A large set of novel communication and content streaming services have become accessible, ranging from simple SMS messaging to live TV broadcasts. This trend is likely to accelerate with the eventual introduction of fully packet switched 4G networks featuring increased bandwidth and global mobility.

Mobile devices are increasingly being used as personal media centers. Traditional boundaries between the roles of information “producer” and “consumer” are blurring as device users produce and distribute content such as personal pictures and videos on their mobile devices. In such a scenario, it makes sense to have technology that lets the individual user retain control over the dissemination of such personal content. It is essential to enable user-level DRM controls for content access, data integrity and rights management.

Currently, most DRM technologies are geared toward the end user being the content consumer, and the DRM protected content coming from a commercial service. The model can be viewed as analogous to a client–server system, with the end user being the client that consumes the content provided by the server, e.g. an online music store. In contrast, we see the need for a personal DRM system that can be viewed as analogous to a peer-to-peer model, with every end user being able to act as content producer, and assert rights and retain control of his or her own content. Any given device can act as both sender (content producer) and recipient (content consumer).

In this paper we discuss a new personal digital rights management system for mobile devices in which a user is able to transparently define, generate, package and migrate content licenses between mobile devices on demand. Our system lets a user select a certain piece of content on a mobile device and associate various controls with it and specify who can consume the content. The controls may include restrictions such as how many times the content can be played etc, as well as whether the content may be exported to other devices.

We designed the personal DRM system and developed a prototype on the Motorola E680i smartphone. Each device automatically detects other personal DRM enabled devices in its proximity and exchanges credentials with them. It presents the user with an efficient graphical user interface that can be used to specify restrictions on any digital content on the phone, and lets the user select a target device to send the content to. Files are transferred between devices using a secure transfer protocol. Each device can play any content it is authorized to, and safely enforces the controls associated with the protected content.