Encryption method of jpeg image bit stream based on the change of AC statistical characteristics

Abstract

A JPEG image bitstream encryption method based on the change of AC statistical characteristics, the user selects the last non-zero AC coefficient entropy encoding in the part of the image block in the JPEG bitstream by the user key, and uses it as secret information through the histogram translation method It is hidden in the entropy coding of some image blocks, the statistical characteristics are obtained from the user key and the AC coefficient, the encryption key of the DC coefficient and the encryption key of the AC coefficient are adaptively generated, and the inter-group scrambling and differential coding iterative setting are performed on the DC coefficient respectively. Intra-block and inter-block scrambling of the AC coefficients; the receiver extracts the secret information from the encrypted bit stream and decrypts it, and recovers the DC coefficient and AC coefficient encryption keys from the user key and the statistical characteristics of the AC coefficients in the encrypted bit stream , and decrypt the AC coefficients and DC coefficients, restore the AC coefficient entropy coding in each image block entropy coding, and obtain the original bit stream. The method has high security and the encrypted file has a small extension.

Description

technical field [0001] The invention relates to a JPEG image bit stream encryption method. Background technique [0002] JPEG (Joint Photographic Experts Group) is the most common image file format for storage, transmission and application in cyberspace. The JPEG compression standard can store digital images in a small space with low loss. With the rapid development of cloud computing and cloud storage, the security of cloud storage data has attracted widespread attention of researchers. Image encryption is an effective means to protect the privacy and security of image content. Encrypting the airspace data of an image will lead to a serious expansion of the image file size, and directly encrypting the JPEG bitstream provides a possible way to achieve privacy-protected image encryption with low storage space. JPEG image has a special encoding method, and the generated encrypted image needs to be compatible with JPEG decoder; therefore, it is a challenging research topic t...

AI Technical Summary

Problems solved by technology

However, the "AC coefficient statistical characteristics" of the self-adaptively generated key used by this algorithm are exactly the same before and after JPEG stream encryption, which is easy to forge. Therefore, this algorithm is vulnerable to chosen plaintext attack; The DC differential coefficient encryption method with built-in randomness and multiple group iterative replacement" realizes that the DCT coefficients do not cross the boundary and protects the visual content of encrypted JPEG images, and effectively reduces the expansion of DC coding

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