Dawen Xu

Data Hiding in Encrypted H.264/AVC Video Streams by Codeword Substitution

Digital video sometimes needs to be stored and processed in an encrypted format to maintain security and privacy. For the purpose of content notation and/or tampering detection, it is necessary to perform data hiding in these encrypted videos. In this way, data hiding in encrypted domain without decryption preserves the confidentiality of the content. In addition, it is more efficient without decryption followed by data hiding and re-encryption. In this paper, a novel scheme of data hiding directly in the encrypted version of H.264/AVC video stream is proposed, which includes the following three parts, i.e., H.264/AVC video encryption, data embedding, and data extraction. By analyzing the property of H.264/AVC codec, the codewords of intraprediction modes, the codewords of motion vector differences, and the codewords of residual coefficients are encrypted with stream ciphers. Then, a data hider may embed additional data in the encrypted domain by using codeword substitution technique, without knowing the original video content. In order to adapt to different application scenarios, data extraction can be done either in the encrypted domain or in the decrypted domain. Furthermore, video file size is strictly preserved even after encryption and data embedding. Experimental results have demonstrated the feasibility and efficiency of the proposed scheme.

A novel watermarking scheme for H.264/AVC video authentication

As the H.264/AVC-based video products become more and more popular, issues of copyright protection and authentication that are appropriate for this standard will be very important. In this paper, a content-based authentication watermarking scheme for H.264/AVC video is proposed. Considering the new feature of H.264/AVC, the content-based authentication code for spatial tampering is firstly generated using the reliable features extracted from video frame blocks. The authentication code, which can detect malicious manipulations but allow recompression, is embedded into the DCT coefficients in diagonal positions using a novel modulation method. Spatial tampering can be located by comparing the extracted and the original feature-based watermarks. In addition, combining ECC and interleaving coding, the frame index of each video frame is used as watermark information and embedded in the residual coefficients. Temporal tampering can be detected by the mismatch between the extracted and the observed frame index. Experimental results show that the proposed scheme can discriminate the malicious tampering from the mild signal processing. The tampered location can also be approximately determined according to the glide window and the predefined threshold.

An improved reversible data hiding-based approach for intra-frame error concealment in H.264/AVC

As H.264/AVC video streams are highly compressed, they become sensitive to errors caused by unreliable transmission channels. In order to address this issue, an improved version of Chung et al.s reversible data hiding-based approach for intra-frame error concealment is proposed for H.264/AVC codec. By using the histogram shifting technique, the original work reversibly embeds the motion vector (MV) of a macroblock (MB) into other MB within the same intra-frame. If an MB is corrupted at the decoder side, the embedded MV can be extracted from the corresponding MB for the recovery of the corrupted MB. However, Chung et al.s work did not fully exploit the number of coefficients which need to be modified in order to reversibly hiding data, and did not consider many extra nonzero residual blocks produced by data hiding. These two issues could reduce the visual quality of the stego-video. This paper adopts MV data pre-processing, the selection of most suitable embedding region, and the minimum possible amount of histogram modification, which lead to higher PSNR of the stego-video for a given payload. Experimental results further reveal that the proposed method offers stego-video with better visual quality over Chung et al.s work.

An improved scheme for data hiding in encrypted H.264/AVC videos

The embedding is done on encrypted H.264/AVC data without knowing the decryption key.The paired code-word substitution and multiple-base notational system are exploited.Both encryption and data embedding keep the bit-rate intact.Data extraction can be carried out either in encrypted or decrypted domain. Recently, a novel scheme to hide data into encrypted H.264/AVC videos using code-word substitution has been proposed by Xu et al. However, the statistical analysis of CAVLC code-words demonstrate that Xu et al.s work does not fully exploit redundancy existing in CAVLC code-word for data embedding. In this paper, an improved version of Xu et al.s data hiding method in encrypted H.264/AVC videos is proposed. Specifically, when suffixLength is equal to 1, data embedding is performed by paired code-word substitution. When suffixLength is greater than 2, not the single code-word substitution but the multiple-based notational system is adopted for data embedding. Experimental results have demonstrated that the improved method is indeed capable of providing a larger embedding capacity in comparison with Xu et al.s method. Moreover, both encryption and data embedding can be accomplished without affecting the coding efficiency of H.264/AVC by keeping exactly the same bitrate.

Blind Digital Watermarking of Low Bit-Rate Advanced H.264/AVC Compressed Video

H.264/AVC is becoming a popular video codec for its better compression ratio, lower distortion and applicability to portable electronic devices. Thus, issues of copyright protection and authentication that are appropriate for this standard become very important. In this paper, a blind video watermarking algorithm for H.264/AVC is proposed. The watermark information is embedded directly into H.264/AVC video at the encoder by modifying the quantized DC coefficients in luminance residual blocks slightly. The watermark embedded in the residuals can avoid decompressing the video and to decrease the complexity of the watermarking algorithm. To reduce visual quality degradation caused by DC coefficients modifying, block selection mechanism is introduced to control the modification strength. Experimental results reveal that the proposed scheme can achieve enough robustness while preserving the perceptual quality.

Two-dimensional reversible data hiding-based approach for intra-frame error concealment in H.264/AVC

Highly compressed video bit-stream is extremely sensitive to transmission error. A novel two-dimensional reversible data hiding-based approach for intra-frame error concealment is proposed, which aims at improving video quality at decoder when video bit-stream incur transmission errors. The scheme involves embedding the motion vector (MV) of a macroblock (MB) into other MB within the same intra-frame, and extracting the embedded MV from the received video frame for reconstruction of the corrupted MB. Based on the distribution of the motion vector data and the characteristic of histogram shifting, a specific two-dimensional reversible data hiding mechanism is designed. Consequently, the distortion of the marked video can be controlled at a low level. Experimental results show that the damaged macroblocks can be recovered with a higher quality using the reversible data hiding methodology, as compared to the non-reversible data hiding method. Furthermore, experimental results demonstrate that the proposed algorithm outperforms some state-of-the-art reversible data hiding error concealment schemes in improving the perceptual quality. MV is embedded by using an improved two-dimensional histogram modification method.The distortion of the marked video can be controlled at a low level.The hidden MV is extracted from the corresponding MB to recover the corrupted MB.

Reversible Data Hiding in Encrypted H.264/AVC Video Streams

Reversible data hiding in the encrypted domain is an emerging technology because of the privacy-preserving requirements from cloud data management. In this paper, a reversible data hiding scheme in encrypted H.264/AVC video streams is proposed. During H.264/AVC encoding, the intra-prediction mode (IPM), motion vector difference (MVD), and residue coefficients’ signs are encrypted using a standard stream cipher. Then, the data-hider, who does not know the original video content, may reversibly embed secret data into the encrypted H.264/AVC video based on histogram-shifting of residue coefficients. With an encrypted video containing hidden data, data extraction can be carried out either in encrypted or decrypted domain. In addition, real reversibility is realized, that is, data extraction and video recovery are free of any error. Experimental results demonstrate the feasibility and efficiency of the proposed scheme.

Low complexity video watermarking algorithm by exploiting CAVLC in H.264/AVC

As H.264/AVC digital video becomes more prevalent, issues of copyright protection and authentication that appropriate for this standard become very important. In this paper, an authentication watermarking algorithm for H.264/AVC compressed video by modulating CAVLC code words of 4×4 luminance blocks is proposed. During the embedding process, the eligible code words are first identified, and then the modulating rules between these code words and the watermark bits are established. The watermark information can be extracted directly from the encoded stream without resorting to the original video, and merely requires decoding the CAVLC code from bit stream rather than decoding the whole video. Experimental results show that the proposed watermarking scheme can effectively embed watermark information with little bit rate increase and almost no quality degradation.

Tunable data hiding in partially encrypted H.264/AVC videos

The encryption of Luma IPMs is designed in addition to residual and motion vector.Data embedding is done on encrypted videos, which preserves the confidentiality.The bin-strings of abs_level and abs_MVD are exploited for data hiding flexibly.The hidden data can be extracted either in encrypted domain or decrypted domain. An improved scheme of data hiding directly in partially encrypted H.264/AVC videos using CABAC bin-string substitution is proposed. The encryption of Luma prediction modes is designed in addition to residual encryption and motion vector encryption in order to significantly improve the structural deterioration. Both the bin-strings of abs_level and the bin-strings of abs_MVD are exploited for data hiding to provide a higher flexibility for users to select the tradeoff between hiding capacity and video quality. Since the data embedding is done in the encrypted domain, the proposed scheme preserves the confidentiality of video content. With an encrypted video containing the hidden data, the receiver can accomplish data extraction directly in encrypted domain using only the data-hiding key, or obtain a decrypted video similar to the original version using only the cryptographic key. Experimental results have demonstrated that the proposed scheme can achieve better scrambling performance and higher embedding capacity.

Completely Separable Reversible Data Hiding in Encrypted Images

As an emerging technology, reversible data hiding in encrypted images will be useful and popular in cloud computing due to its ability to preserve the confidentiality. In this paper, a novel framework of completely separable reversible data hiding in encrypted images is proposed. The cover image is first partitioned into non-overlapping blocks and specific encryption is applied to obtain the encrypted image. Then, image difference in the encrypted domain can be calculated based on the homomorphic property of the cryptosystem. The data-hider, who does not know the original image content, may reversibly embed secret data into image difference using a modified version of histogram shifting technique. Data extraction is completely separable from image decryption, i.e., data extraction can be done either in the encrypted domain or in the decrypted domain, so that it can be applied to different application scenarios. In addition, real reversibility is realized, that is, data extraction and image recovery are free of any error. Experimental results demonstrate the feasibility and efficiency of the proposed scheme.