Efficient Multi-dimensional Key Management in Broadcast Services

The prevalent nature of Internet makes it a well suitable medium for many new types of services such as location-based services and streaming content. Subscribers to such services normally receive encrypted content and can obtain access to it if they possess the corresponding decryption key. Furthermore, in location-based services a subscription is normally granted to a geographic area specified by user-specific coordinates (

x

1

,

x

2

), (

y

1

,

y

2

) and custom time interval (

t

1

,

t

2

). Similarly, subscriptions to other services also involve multiple dimensions. The problem of key management is then to assign keys to each point on a

D

-dimensional grid and to subscribers in such a way as to permit all users to obtain access only to the resources in their subscriptions and minimize the associated overhead. In this work, we develop a novel key management scheme for multi-dimensional subscriptions that both outperforms existing solutions and supports a richer set of access privileges than existing schemes. Our scheme is provably secure under the Decision Linear Diffie-Hellman Assumption.