Secure media sharing in the cloud: Two-dimensional-scalable access control and comprehensive key management

Media sharing in cloud environment, which supports sharing media content at any time and from anywhere, is a promising paradigm of social interaction. However, it also brings forth security issues in terms of data confidentiality and access control on media data consumers with different access privileges. One promising solution is scalable media access control, which is capable of providing data confidentiality by encrypting the media data and issuing the key to only authorized data consumers. More importantly, it can empower the data distributor to provide the same media content with various quality levels to the consumers with different privileges. Traditional schemes without utilizing the cloud resources achieve scalable media access control by generating access keys using hash chains. Despite of their computational efficiency, such schemes suffer from various problems including vulnerability to user collusion attack in two-dimensional case, inflexible key distribution, and ambiguous key revocation strategy. In this paper, we propose a novel two-dimensional-scalable access control by generating access keys based on Attribute-Based Encryption (ABE) algorithm. Moreover, the proposed scheme can efficiently achieve comprehensive key management including key distribution and key revocation by fully exploiting the cloud. Security analysis shows that the proposed scheme is able to provide collusion resistance, as well as forward and backward secrecy. We have also evaluated the efficiency of the scheme through numerical analysis and initial implementation.