Sufficient encryption based on entropy coding syntax elements of H.264/SVC

Abstract

While much attention has been paid to securing the transmission of single-layer video, multi-layer scalable video also deserves consideration. This paper presents a sufficient encryption (SE) scheme for the H.264 Scalable Video Coding (SVC) extension that maintains the compression efficiency and the decoder format compliancy of the bitstream, without compromising its confidentiality. SE is achieved by applying encryption of carefully selected codewords or bin-strings of the Context-Adaptive Variable-Length Coding (CAVLC) and Context-Adaptive Binary Arithmetic Coding (CABAC) entropy coders respectively. The selection of exactly what to encrypt is what distinguishes this contribution from that of others. The performance of the scheme is tested on sequences with varying spatial resolutions, thus demonstrating the advantages of the scheme when compared to alternative techniques. These advantages include: minimal computational delay by encrypting partial data; no bit-rate escalation by keeping the compression ratio unchanged; and format compliancy of the bit-stream at the decoder. The detailed security and comparative evaluation of the scheme confirms that it is suitable for commercial, real-time applications. As there is a minimal increase in processing requirements, the scheme is highly suitable for video distribution to users who have subscribed to differing video qualities on end systems ranging from small handheld devices to those capable of high spatial resolutions and frame rates.

Lightweight Cipher for H.264 Videos in the Internet of Multimedia Things with Encryption Space Ratio Diagnostics

“…Thus, the ESR of delta QP combined with motion (0.50% for mobile video and 0.14% for ICE video) or delta QP combined with texture (12.80% for mobile video and 4.15% for ICE video) is also less as compared to the encryption ratio with combined motion and texture (13.22% for mobile video and 4.21% for ICE video). The important point to note here is that the SE on the absolute values of dQP is not possible with complex cipher algorithms, because the number of rounds in complex ciphers makes these values out of range which destroys the format compliance and compression efficiency of the bitstream, and consequently crashes the decoder [ 52 ].…”

“…In this paper, for the convenience of implementation the focus is not on a newly proposed SE encoder technique. Therefore, we have employed our previous SE schemes for example as reported in [ 52 ], with one newly identified parameter for enhanced visual protection of videos. For the convenience of new researchers, we give simple names to these selected parameters, such as (1) motion, dealing with the movement of objects in videos including camera zooming and other viewing adjustments (2) texture data for pixels information, and a new parameter (3) difference of quantization parameters (deltaQP).…”

Visual Surveillance Within the EU General Data Protection Regulation: A Technology Perspective

“…The obfuscated videos may remain format compliant, and playable in the distorted form. The obfuscation is applied by strong ciphers, so that the adversary is not able to reconstruct the recognizable version through inference attacks [42]. 3) Transparent/perceptual encryption: This is applied over multiple versions of a video [43]; a lower quality version is free to view but to view a full-quality version, the encryption key is required.…”

Effectiveness of crypto-transcoding for H.264/AVC and HEVC video bit-streams

“…Nonetheless, these weaknesses can be addressed by ensuring that SE is performed at the final stage of a hybrid video encoder [26] i.e. entropy-coding stage, and after ensuring that statistical distribution of encrypted syntax elements will not be altered [27]. Only then does SE become beneficial as no or limited extra bit-rate overhead occurs.…”

“…However, there may be a bitrate overhead arising from scalable coding, though HEVC variants of SVC [40] have gone some way to address that issue by considering inter-layer prediction. Encryption of H.264/SVC was considered in [27]. It is also possible [41] to apply a form of transcoding to encrypted scalable video after packetization.…”