Intra-class coefficient scrambling-based JPEG image encryption method

Abstract

The invention relates to an intra-class coefficient scrambling-based JPEG image encryption method. The method comprises the following steps: firstly reading in a JPEG image file, acquiring a Huffman coding table and image data which undergoes JPEG coding compression, carrying out decoding to acquire all the non-zero quantized DCT coefficient numerical values and positions and carrying out classification; selecting a password, carrying out chaotic iteration by utilizing the password, so as to generate a chaotic sequence, and scrambling the non-zero coefficients and 8*8 block of each class by utilizing the chaotic sequence; and carrying out entropy coding on a scrambled quantized DCT coefficient matrix, and writing the coded data into the JPEG image file so as to complete intra-class coefficient scrambling-based JPEG image encryption. According to the method disclosed in the invention, scrambling is carried out on different classes of quantized DCT coefficients through the chaotic sequence, and the quantized DC coefficients and the non-zero AC coefficients are processed by directly using one encryption scheme, so that the safety and the high efficiency are both considered; and the encrypted images are similar to clear text image files in the aspect of size, and have high compression ratios.

Description

【Technical field】 [0001] The invention belongs to the technical field of image processing and relates to a JPEG image encryption method based on similar coefficient scrambling. 【Background technique】 [0002] With the development of hardware technology, image acquisition equipment is becoming more and more popular. At present, most image acquisition equipment saves the acquired image data in JPEG format. When these images are released and exchanged through public networks, the encryption requirements for private content are also required. Every day. Image encryption hides visual information through algorithms to protect data security. Traditional image encryption methods focus on hiding content and details, regardless of the storage format of image data and the compression rate of encrypted ciphertext images. The ciphertext image obtained by using the traditional encryption method on the JPEG image has a much lower compression rate than the plaintext image due to the unifo...

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Problems solved by technology

For example in SimYing Ong, KokSheik Wong, Xiaojun Qi, Kiyoshi Tanaka, "Beyond format-compliant encryption for JPEG image", Signal Processing: Image Communication, Volume 31, February, Pages 47-60, 2015. Separately encrypt quantized DC and non-zero AC Coefficients: Encrypt the quantized DC coefficients and quantized non-zero AC coefficients in different ways, requiring at least two encryption schemes, and the whole system is more complicated

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