Method and system for JPEG image decompression under ciphertext based on homomorphic encryption

Abstract

The invention discloses a method and a system for JPEG image decompression under ciphertext based on homomorphic encryption, belonging to the technical field of multimedia information protection. Themethod comprises the following steps: encrypting a JPEG image through a homomorphic encryption method, thereby protecting privacy information in the image; obtaining a ciphertext code stream through asingle instruction multiple data encryption method; in a Huffman decoding process, eliminating branch operations in entropy coding through a static iterative method, obtaining one DCT coefficient byperforming iterative operation once, and decoding out all the DCT coefficients through performing iterative operation for many times; matching each code word through a code matching table to decode out the DCT coefficient, and finally converting floating-point arithmetic into integer arithmetic through integer inverse DCT in HEVC, thereby obtaining a decoded pixel value. With the method and the system provided by the invention, decompression of cloud JPEG images under a homomorphic domain can be realized, the homomorphically encrypted pixel value can be obtained for follow-up coherent processing of the homomorphic domain, and image privacy information is protected.

Description

technical field [0001] The invention belongs to the field of multimedia information protection, and more specifically relates to a method and system for decompressing a JPEG image under ciphertext based on homomorphic encryption. Background technique [0002] With the advent of the era of cloud computing, more and more multimedia data is stored in the cloud, and distributed processing and analysis are carried out through cloud computing. However, public cloud computing is remotely controlled by a third party, and cloud users cannot directly manage or monitor the usage of computing resources and customer data, and there may be privacy leaks. Cloud users lose control over data, making privacy protection a key issue in cloud computing. [0003] In order to protect the multimedia privacy information on the cloud, the key point is encryption. Homomorphic encryption uses a specially designed form of encryption that allows computations to be performed on ciphertext, and the resul...

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Problems solved by technology

[0006] Aiming at the above defects or improvement needs of the prior art, the present invention provides a method and system for decompressing JPEG image ciphertexts based on homomorphic encryption, thereby solving the problem that matching cannot be determined during JPEG decoding under homomorphic ciphertexts. The codeword, and thus the number of coefficients that are solved cannot be determined, and the technical problem of the decoding result cannot be determined

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