A number of image encryption techniques have been proposed in recent years. These techniques use either spatial or transform domain image processing. A major challenge when designing an image encryption scheme is to conceal the pixel of the input image, especially when the image has a low texture region. Another problem is the encryption computational time. In this paper, these two issues are addressed. As the use of a single substitution box (S-box) to encrypt digital images does not work well for greater as well as a lower number of gray levels. To solve this problem, a new substitution technique using multiple S-boxes with dynamic substitution is proposed. In the second part of this paper, the proposed discrete wavelet transform based scheme is employed to reduce the encryption computational time. A number of parameters like correlation, entropy, energy, contrast, homogeneity, MSE and PSNR are used to analyze the quality of cipher images.

近年来，已经提出了许多图像加密技术。这些技术使用空间或变换域图像处理。设计图像加密方案时的主要挑战是隐藏输入图像的像素，尤其是当图像的纹理区域较低时。另一个问题是加密计算时间。本文解决了这两个问题。由于使用单个替换盒（S-box）加密数字图像对于灰度级别的提高和降低都不太有效。为了解决这个问题，提出了一种使用多个具有动态替换的S盒的替换技术。在本文的第二部分中，提出的基于离散小波变换的方案被用来减少加密计算时间。许多参数，例如相关性，