A Scalable and Format-Compliant Encryption Scheme for H.264 ...

Table 7: Comparison between the proposed scheme and other SVC encryption schemes[11, 12, 13] [18] [19, 20, 21] [22, 23] Present[14, 15, 16]Security low medium high high highScalability yes yes yes no yes-transparencyFormat yes yes no yes yes-complianceComputation low low medium medium mediumcomplexityCompression no 15 1.30 ∼ 3.4 0.92 ∼ 2.0 0.8 ∼ 2.8overhead(%)For compression overhead, [11, 12, 13, 14, 15, 16] have no compressionoverhead except of [18]; [19, 20, 21, 22, 23] can cause compression overheadif stream and block cipher have an initial vector (128bit) for each NALUand handle synchronization markers of H.264. Our proposed scheme causesimilar compression overhead while this trades-off with additional propertiese.g., adaptation-transparency, format-compliance and low computationcomplexity.7. ConclusionsThis paper presents a novel encryption scheme for SVC bitstreams. Thescheme creates new NALUs to replace the original VCL NALUs. Becauseeach new NALU has an SVC NAL header which indicates the scalability informationin an SVC bitstream, the encrypted bitstream preserves the SVCscalability. At the same time, since the payload of each new NALU is identifiedas user data unregistered message, the encrypted bitstream satisfiesthe SVC specification. The experimental results indicate that the proposedscheme incurs little overhead and has low processing cost.AcknowledgmentThis work was supported in part by A*STAR SERC Grant No. 102 1010027 in Singapore.28