Marc Chaumont

A reversible data hiding method for encrypted images

Since several years, the protection of multimedia data is becoming very important. The protection of this multimedia data can be done with encryption or data hiding algorithms. To decrease the transmission time, the data compression is necessary. Since few years, a new problem is trying to combine in a single step, compression, encryption and data hiding. So far, few solutions have been proposed to combine image encryption and compression for example. Nowadays, a new challenge consists to embed data in encrypted images. Since the entropy of encrypted image is maximal, the embedding step, considered like noise, is not possible by using standard data hiding algorithms. A new idea is to apply reversible data hiding algorithms on encrypted images by wishing to remove the embedded data before the image decryption. Recent reversible data hiding methods have been proposed with high capacity, but these methods are not applicable on encrypted images. In this paper we propose an analysis of the local standard deviation of the marked encrypted images in order to remove the embedded data during the decryption step. We have applied our method on various images, and we show and analyze the obtained results.

Fast Protection of H.264/AVC by Selective Encryption of CAVLC and CABAC for I and P Frames

This paper presents a novel method for the protection of bitstreams of state-of-the-art video codec H.264/AVC. The problem of selective encryption (SE) is addressed along with the compression in the entropy coding modules. H.264/AVC supports two types of entropy coding modules. Context-adaptive variable length coding (CAVLC) is supported in H.264/AVC baseline profile and context-adaptive binary arithmetic coding (CABAC) is supported in H.264/AVC main profile. SE is performed in both types of entropy coding modules of this video codec. For this purpose, in this paper the encryption step is done simultaneously with the entropy coding CAVLC or CABAC. SE is performed by using the advanced encryption standard (AES) algorithm with the cipher feedback mode on a subset of codewords/binstrings. For CAVLC, SE is performed on equal length codewords from a specific variable length coding table. In case of CABAC, it is done on equal length binstrings. In our scheme, entropy coding module serves the purpose of encryption cipher without affecting the coding efficiency of H.264/AVC by keeping exactly the same bitrate, generating completely compliant bitstream and utilizing negligible computational power. Owing to no escalation in bitrate, our encryption algorithm is better suited for real-time multimedia streaming over heterogeneous networks. It is perfect for playback on handheld devices because of negligible increase in processing power. Nine different benchmark video sequences containing different combinations of motion, texture, and objects are used for experimental evaluation of the proposed algorithm.

Fast protection of H.264/AVC by selective encryption of CABAC

This paper presents a novel method for the protection of copyrighted multimedia content. The problem of selective encryption (SE) is being addressed along with the compression for the state of the art video codec H.264/AVC. SE is performed in the context-based adaptive binary arithmetic coding (CABAC) module of video codec. For this purpose, CABAC is converted to an encryption cipher. It has been achieved through scrambling of equal length bin strings. In our scheme, CABAC engine serves the purpose of encryption cipher without affecting the coding efficiency of H.264/AVC by keeping exactly the same bit rate, generating completely compliant bitstream and utilizing negligible computational power. Owing to no escalation in bit rate, our encryption algorithm is better suited for real-time multimedia streaming. It is perfect for playback on handheld devices because of negligible increase in processing power. Nine different benchmark video sequences containing different combinations of motion, texture and objects are used for experimental evaluation of the proposed algorithm.

Considering the reconstruction loop for watermarking of intra and inter frames OF H.264/AVC

This paper presents and analyzes a new approach to data hiding that embeds in both the intra- and inter-frames from the H.264/AVC video codec. Most of the current video data hiding algorithms take into account only the intra-frames for message embedding. This may be attributed to the perception that inter-frames are highly compressed due to the motion compensation, and any embedding message inside these may adversely affect the compression efficiency significantly. Payload of the inter-frames is also thought to be less, compared with the intra-frames, because of the lesser residual data. We analyze data hiding in both intra- and inter-frames over a wide range of QP values and observe that the payload of the inter is comparable with that of the intra-frames. Message embedding, in only those non-zero quantized transform coefficients (QTCs) which are above a specific threshold, enables us to detect and extract the message on the decoding side. There is no significant effect on the overall bitrate and PSNR of the video bitstream because instead of embedding message in the compressed bitstream, we have embedded it during the encoding process by taking into account the reconstruction loop. For the non-zero QTCs, in the case of intra-frames, we benefit from the spatial masking, while in the case of inter-frames, we exploit the motion and texture masking. We can notice that the data hiding is done during the compression process and the proposed scheme takes into account the reconstruction loop. The proposed scheme does not target robustness and the obtained payload is higher, with a better trade-off in terms of quality and bitrate, as compared with previous works.

FAST PROTECTION OF H.264/AVC BY SELECTIVE ENCRYPTION

This paper presents a novel method for the protection of copyrighted multimedia content. The problem of selective encryption (SE) has been addressed alongwith compression for the state of the art video codec H.264/AVC. SE is performed in the context-based adaptive binary arithmetic coding (CABAC) module of video codec. For this purpose, CABAC is converted to an encryption cipher by scrambling of equal length binarized code words. In our scheme, CABAC engine serves the purpose of encryption cipher without affecting the coding efficiency of H.264/AVC by keeping the original bitrate, generating completely compliant bitstream and utilizing negligible computational cost. Nine different benchmark video sequences containing different combinations of motion, texture and objects have been subjected to experimental evaluation of the proposed algorithm.

Selective and scalable encryption of enhancement layers for dyadic scalable H.264/AVC by scrambling of scan patterns

This paper presents a new selective and scalable encryption (SSE) method for intra dyadic scalable coding framework based on wavelet/subband (DWTSB) for H.264/AVC. It has been achieved through the scrambling of quantized transform coefficients (QTCs) in all the subbands of DWTSB. To make the encryption scalable, it takes advantage of the prior knowledge of the frequencies which are dominant in different high frequency (HF) subbands, as traditional zigzag scan is not that efficient for them. Thus, by scrambling the scan order of QTCs in the intra scalable coding framework of H.264/AVC, we were able to get encryption and compression for enhancement layers (ELs) simultaneously. Watermarking has been integrated in the proposed architecture to avoid the requirement of separate keys for each spatial layer. The algorithm is better suited for multimedia streaming as the bitrate of the encrypted bitstream is lower than the original bitrate. Besides offering SSE, the proposed algorithm, when applied to different benchmark video sequences, outperformed the standard zigzag scan in terms of bitrate.

A Grey-Level Image Embedding its Color Palette

In this paper, we propose a method to embed the color information of an image in its corresponding grey-level image. The objective of this work is to allow free access to the grey-level image and give color image access to secret key owners. This method is made of two steps which are the color image decomposition (in a grey-level image and its associated color information) and the data-hiding. The main contribution of this paper is the energetic function proposed to model the decomposition of the color image. The optimization of the proposed energetic function leads to the obtention of an index image and a color palette. The good properties of that decomposition are an index image which is similar to the luminance of the color image and a color palette which is well suit for the data-hiding. The obtained results confirm the model quality.

Spread spectrum-based watermarking for Tardos code-based fingerprinting for H.264/AVC video

In this paper, we present a novel approach for active finger-printing of state of the art video codec H.264/AVC. Tardos probabilistic fingerprinting code is embedded in H.264/AVC video signals using spread spectrum watermarking technique. Different linear and non-linear collusion attacks have been performed in the pixel domain to show the robustness of the proposed approach. The embedding has been performed in the non-zero quantized transformed coefficients (QTCs) while taking into account the reconstruction loop.

A fast and efficient method to protect color images

In this paper, we propose a method to embed the color information of an image in a corresponding grey-level image. The objective of this work is to allow free access to the grey-level image and give color image access only if you own a secret key. This method is made of three major steps which are a fast color quantization, an optimized ordering and an adapted data hiding. The principle is to build an index image which is, in the same time, a semantically intelligible grey-level image. In order to obtain this particular index image, which should be robust to data hiding, a layer running algorithm is proceeded to sort the K colors of the palette. The major contributions of this paper are the fast color quantization, the optimized layer running algorithm, the color palette compression and the adapted data hiding.

Robust and real-time 3D-face model extraction

This article deals with 3D-face model and 3D-pose extraction from a small set of couples of 2D-3D corresponding-points. Major drawbacks of current 3D model extraction solutions are either the computationally complexity or the over-simplified modeling. As it happens, applications like face tracking or augmented reality need a rapid, robust and descriptive-enough solution. The solution we propose is based on a two step approach in which an approximation of a 3D-face model and a 3D pose is computed and then refined in order to extract more precise parameters. The contribution of this paper is to describe how to efficiently (rapidly and robustly) solve the problem of 3D-face model and 3D pose extraction. The results obtained show rapid and robust performances which could be exploited in a more global real-time face tracking application.