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Document Type

Article

Keywords

Affine transformation, Arnold map, Keyspace, PSNR, RGB image, TEA

Abstract

In digital images, protecting sensitive visual information against unauthorized access is considered a critical issue; robust encryption methods are the best solution to preserve such information. This paper introduces a model designed to enhance the performance of the Tiny Encryption Algorithm (TEA) in encrypting images. Two approaches have been suggested for the image cipher process as a preprocessing step before applying the Tiny Encryption Algorithm (TEA). The step mentioned earlier aims to de-correlate and weaken adjacent pixel values as a preparation process before the encryption process. The first approach suggests an Affine transformation for image encryption at two layers, utilizing two different key sets for each layer. The dual encryption process achieves high diffusion and confusion properties for the cipher process. The second approach proposed a chaotic Arnold map before the Tiny Encryption Algorithm (TEA) process. Various statistical measures are used, such as Peak Signal to Noise Ratio (PSNR), Structural Similarity Index (SSIM), and Image Quality Index (IQI). For example, the lower PSNR, SSIM, and IQI values indicate better results for test image Lina of the second approach. The obtained results for the previous measures of the second approach are 8.5449, 0.0008, and -0.0061, compared to the first approach, 8.5529, 0.0054, -0.0015, respectively. Moreover, key space and time analysis are used to assess the encryption process. The outcomes show a high-key space 32,768*2128 ) and a slight encryption time of 130 milliseconds for the first approach and 1862 milliseconds for the second approach.

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