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In order to cope with the problem that reversible data hiding in encrypted images(RDHEI) has lower embedding capacity, this paper proposed a high-capacity RDHEI method based on prediction error dual coding. Firstly, to reserve space for secret data, the image owner preprocessed the image using prediction error-based Huffman coding and extended run-length coding, and then encrypted the image. The data hider embedded secret data in the encrypted image. The receiver could extract the secret data accurately according to the data hiding key and recover the image losslessly according to the decryption key, it separated data extraction and image decryption. The experimental results demonstrate that the embedding capacity is effectively improved by prediction error dual coding. [ABSTRACT FROM AUTHOR]

This paper proposed a privacy-preserving data publishing method based on autoencoder and time-frequency trans-formation to avoid privacy disclosure from the stream data of wearable devices. Firstly, this method transformed slide window data into frequency spectrum by the block discrete cosine transformation. Secondly, it desensitized frequency spectrum by autoencoder. Finally, it obtained slide window data from reconstructed frequency spectrum by the inverse block discrete cosine transformation. This paper applied pre-trained activity and identity classifiers to evaluate the privacy and utility of autoencoder' s output, then updated the weights of network by multi-objective loss function and back propagation. The experimental results on the Motion-Sense dataset show that the F1 -score of activity recognition on the reconstructed data is reduced from 0.944 to 0.940, the F1-score of identity recognition is reduced from 0.908 to 0.673, and the mean square error between reconstructed acceleration data and original data is 0.27. Compared with similar algorithms, this proposed algorithm can better retain the utility of data and improve data security. [ABSTRACT FROM AUTHOR]

In order to improve the information embedding rate and implement real reversibility of data hiding technology, combined with the characteristics of medical image (huge data and high continuity of same color pixels), this paper proposed a reversible data hiding algorithm based on encrypted medical images. At first, it preprocessed image and constructed header information. The scheme obtained the maximum embedding rate using edge detection, and compressed boundary portion using run length coding (RLC) to vacate room. And it made the information hiding algorithm reversible completely. Then it encrypted the image using chaotic algorithm. Finally, it embedded watermark information in the encrypted image by replacing the least significant bits. The theoretical analysis and simulations show that the algorithm has high information embedding capacity and good invisibility, which reaches a high level in aspect of the correlation coefficient, the entropy value, peak signal to noise ratio. [ABSTRACT FROM AUTHOR]

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