An efficient key scheme for layered access control of MPEG-4 FGS video

The recently proposed scalable multi-layer FGS (fine granularity scalability) encryption (SMLFE) encrypts an MPEG-4 FGS stream into multiple PSNR and bitrate quality layers for layered access control. Both layer types are supported simultaneously. A simple key scheme was used in SMLFE. We propose a novel key scheme for SMLFE that reduces the number of keys maintained and managed by a license server for each protected MPEG-4 FGS stream to two. The new key scheme needs only one key contained in a license to be sent to a consumer. This scheme is based on a cryptographic secure hash function and the Diffie-Hellman key agreement. It satisfies all the requirements of SMLFE and can be used to replace the original simple key scheme for SMLFE. The secure one-way hash and intractability of the Diffie-Hellman and the related problems of computing discrete logarithms ensure the security of the new key scheme.