JPEG image bit stream encryption method based on alternating current statistical characteristic change

Abstract

The invention discloses a JPEG image bit stream encryption method based on alternating current statistical characteristic change. The method comprises: in a JPEG bit stream, a user selects the last non-zero communication coefficient entropy code in a part of image blocks by using a user key to encrypt; hiding the secret information into a part of image block entropy codes through a histogram translation method; statistical characteristics are obtained through a user secret key and an alternating current coefficient, a direct current coefficient encryption secret key and an alternating currentcoefficient encryption secret key are generated in a self-adaptive mode, inter-group scrambling and differential coding iteration scrambling are carried out on the direct current coefficient, and intra-block scrambling and inter-block scrambling are carried out on the alternating current coefficient; and the receiver extracts secret information from the encrypted bit stream and decrypts the secretinformation, recovers the direct current coefficient and the alternating current coefficient encryption key according to the user key and the alternating current coefficient statistical characteristics in the encrypted bit stream, decrypts the alternating current coefficient and the direct current coefficient, recovers the alternating current coefficient entropy code in each image block entropy code, and obtains the original bit stream. The method is high in security and small in encrypted file expansion.

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

Images