Benoit Boyadjis

A real-time ciphering transcoder for H.264 and HEVC streams

This paper presents a novel approach for real-time encryption of both H.264 and HEVC encoded streams. Our method relies on structure-preserving Selective Encryption (SE) managed by a symmetric ciphering/deciphering transcoder. Developped as an autonomous tool, it can be implemented within any existing software and hardware architecture and requires very low computational cost. The Advanced Encryption Standard (AES) manages the encryption step to guarantee the protection of encrypted streams. Our method preserves source format and overall bitrate, which ensures undetectable ciphering and suitability for streaming over heterogeneous networks. Experimental evaluation of our proposed transcoder is provided in this paper and a demonstrator of an implementation on a mobile device will support these theoretical results.

Extended Selective Encryption of H.264/AVC (CABAC)- and HEVC-Encoded Video Streams

This paper proposes an extended selective encryption (SE) method for both H.264/advanced video coding (AVC) (CABAC) and High Efficiency Video Coding (HEVC) streams, addressing the main security issue that SE is facing: content protection, related to the amount of information leakage through a protected video. Our contribution is the improvement in the visual distortion induced by SE approaches. Previous works on both H.264/AVC (CABAC) and HEVC limit encryption to bins treated by one specific mode of CABAC—its bypass mode—which has the advantage of preserving the overall bitrate, we propose here to also rely on the encryption of the more widely used mode of CABAC—its regular mode. This allows encryption of a major codeword for video reconstruction, the prediction modes for intra blocks/units. Disturbing their statistics may cause bitrate overhead, which is the tradeoff for improving the content security level of the SE approach. A comprehensive study of this compromise between the improvement in the scrambling efficiency and the undesirable aftereffects is presented in this paper, and a specific security analysis of the proposed CABAC regular mode encryption is conducted.

Auto-synchronized selective encryption of video contents for an improved transmission robustness over error-prone channels

Selective encryption designates a technique that aims at scrambling a message content while preserving its syntax. Such an approach allows encryption to be transparent towards middle-box and/or end user devices, and to easily fit within existing pipelines. In this paper, we propose to apply this property to a real-time diffusion scenario - or broadcast - over a RTP session. The main challenge of such problematic is the preservation of the synchronization between encryption and decryption. Our solution is based on the Advanced Encryption Standard in counter mode which has been modified to fit our auto-synchronization requirement. Setting up the proposed synchronization scheme does not induce any latency, and requires no additional bandwidth in the RTP session (no additional information is sent). Moreover, its parallel structure allows to start decryption on any given frame of the video while leaving a lot of room for further optimization purposes.

Super-resolution of HEVC videos via convex optimization

Super Resolution (SR) addresses the problem of image and video upscaling. Most of the best performing SR methods do not take into account any compression prior into the degradation model. Consequently, compression artifacts can be undesirably amplified during SR. In the present work, we propose a novel HEVC-dedicated approach for embedding SR results into a domain that closely fits the compressed observation. Our main contribution is the inclusion of HEVC syntax (block size, quantization parameters etc.) into the degradation model. A recent convex optimization approach is used to solve the associated minimization problem. Over a wide range of resolutions and bitrates, we show that our method improves the results obtained with state of the art SR.

Real-time selective encryption solution based on ROI for MPEG-A visual identity management AF

As part of a new MPEG-A standardization activity, called Visual Identity Management Application Format (VIMAF), this paper presents an end-to-end encryption solution of Region of Interest (ROI) in both AVC and HEVC encoded streams for privacy protection applications. This solution uses a selective encryption method that encrypts only the most sensitive information of the video and proposes a new adapted syntax in order to facilitate interoperability between equipment. Objective video quality measurements have shown the robustness of the proposed selective encryption solution with only a slight bitrate increase.

Background simplification for ROI-oriented low bitrate video coding

Low-bitrate video compression is a challenging task, particularly with the increasing complexity of video sequences. Re-shaping video data before its compression with modern hybrid encoders has provided interesting results in the low and ultra-low bit rate domains. In this work, we propose a novel saliency guided preprocessing approach, which combines adaptive re-sampling and background texture removal, to achieve efficient ROI-oriented compression. Evaluated with HEVC, we show that our solution improves the ROI encoding over a wide range of resolutions and bit rates whilst maintaining a high background intelligibility level.