Perceptual Encryption of H.264 Videos: Embedding Sign-Flips Into the Integer-Based Transforms

• Published in: IEEE transactions on information forensics and security Vol. 9; no. 2; pp. 309 - 320
• Main Authors: Bing Zeng, Siu-Kei Au Yeung, Shuyuan Zhu, Gabbouj, Moncef
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Butterflies; Coding, codes; Computer information security; Cryptography; Discrete cosine transforms; Encoding; Encryption; Equivalence; Exact sciences and technology; H.264/AVC; Information, signal and communications theory; integer-based transforms; perceptual video encryption; Security; Signal and communications theory; Strategy; Telecommunications and information theory; Transforms; Video encryption; Video signals; Videos; Video coding; Network structure; Video signal; integer-based transforms; H.264/AVC; Graph flow; Video encryption; perceptual video encryption; Persistence; Perceptual encryption; Safety; Cryptography; Discrete cosine transforms; Rotation angle
• ISSN: 1556-6013; 1556-6021
• DOI: 10.1109/TIFS.2013.2293955

An alternative-transforms-based scheme has recently been proposed to achieve perceptual encryption of video signals in which multiple transforms are designed by using different rotation angles at the final stage of the discrete cosine transforms (DCTs) butterfly flow-graph structure. More recently, it is found that a set of more efficient alternative transforms can be derived by introducing sign-flips at the same stage, which is equivalent to an extra rotation angle of π. In this paper, we generalize this sign-flipping technique by randomly embedding sign-flips into all stages of the DCTs butterfly structure so that the encryption space becomes much larger to yield a higher security. We pursue this study for H.264-compatible videos, assuming that the integer DCT of size 4 × 4 is used. First, we follow the separable implementation of the 4 × 4 2-D DCT in which different sign-flipping strategies will be employed along its horizontal and vertical dimensions. Second, we convert the 4 × 4 2-D DCT into a 16-point 1-D butterfly structure so that more sign-flips can be embedded at its various stages. Third, we choose different schemes to pair the node-variables in the 16-point 1-D butterfly structure, thus further enlarging the encryption space. Extensive experiments are conducted to show the performance of these improved encryption schemes and some security analyzes are also presented to confirm their persistence to various attacking strategies.