JPEG-compatible Joint Image Compression and Encryption Algorithm with File Size Preservation

Abstract

Joint image compression and encryption algorithms are intensively investigated due to their powerful capability of simultaneous image data compression and sensitive information protection. Unfortunately, most of the existing algorithms suffered from either poor compression efficiency or weak encryption strength, making them vulnerable to cryptanalysis. To address these limitations, we propose a chaos-based JPEG-compatible joint image compression and encryption algorithm. We separate the luminance and chrominance coefficients to preserve file size and encrypt the discrete cosine transform (DCT) coefficients in parallel. The proposed inter-block DC encryption strategy achieves high encryption intensity based on permutation-substitution structure. In addition, we apply both inter- and intra-block permutations to AC coefficients, and strengthen the encryption using an inter-block substitution for non-zero AC coefficients. The result of security and performance analyses demonstrate that the proposed algorithm offers robust encryption of image data while maintaining compression efficiency for real-time transmission.

Security Improvements of JPEG Images Using Image De-Identification

“…The following Table 5 summarizes the previously studied methods of encrypting images [2] and the encryption times of image encryption using chaotic logistic maps [19]. Furthermore, the method proposed in [20] has excellent security and is based on the Jia chaotic system and a logistic map. Note that the algorithm introduced in [20] prioritizes security over encryption speed.…”

“…Furthermore, the method proposed in [20] has excellent security and is based on the Jia chaotic system and a logistic map. Note that the algorithm introduced in [20] prioritizes security over encryption speed. Nevertheless, we can see that is notably slower than our proposed approach.…”

Encryption Method for JPEG Bitstreams for Partially Disclosing Visual Information

“…In addition, cloud services are generally unreliable due to incidents such as information leakage. Accordingly, various encryption methods that can preserve the JPEG format have been studied so far [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. An example of encryption methods that can maintain the JPEG format is methods used in encryption-then-compression (EtC) systems [1][2][3], although the traditional way of securely transmitting images is to use a compression-thenencryption (CtE) system.…”

“…There are other methods that can generate encrypted JPEG images [10][11][12][13][14][15]. In the methods proposed in [10][11][12], encryption is applied in the DCT domain after quantization, and a format-compliant encoded sequence is output.…”

“…There are other methods that can generate encrypted JPEG images [10][11][12][13][14][15]. In the methods proposed in [10][11][12], encryption is applied in the DCT domain after quantization, and a format-compliant encoded sequence is output. However, these methods cannot also preserve the file size of original JPEG images without encryption, and they cannot generate partially encrypted images.…”