Abstract
As a subset of discrete Fourier transform (DFT), discrete cosine transform (DCT), especially two-dimensional discrete cosine transform (2D-DCT), is an important mathematical tool for digital signal processing. However, the computational complexity of 2D-DCT is quite high, which makes it impossible to meet the requirements in some signal processing fields with large signal sizes. In addition, to optimize the 2D-DCT algorithm itself, seeking help from a cloud platform is considered to be an excellent alternative to dramatically speeding up 2D-DCT operations. Still, there are three key challenges in cloud computing outsourcing that need to be addressed, including protecting the privacy of input and output data, ensuring the correctness of the returned results, and ensuring adequate local cost savings. In this paper, we explore the design of a practical outsourcing protocol for 2D-DCT and 2D-IDCT, which well solves the above three challenges. Both theoretical analysis and simulation experiment results not only confirm the feasibility of the proposed protocol but also show its outstanding performance in efficiency.
Highlights
discrete Fourier transform (DFT) is a common tool for frequency domain analysis of discrete signals and systems, but it is inconvenient to process image and voice data due to the need for complex domain operations
discrete cosine transform (DCT) is considered to be a quasioptimal tool for transforming image and voice signals and is widely used in various fields such as media compression [1]–[3], digital watermarking [4]–[6], and wireless communication [7, 8]. 2D-DCT can directly transform two-dimensional data, so it is quite suitable for the analysis and processing of two-dimensional signals, such as static images
For example, are widely used in habitat monitoring, target detection, and espionage [10, 11], where nodes typically use processors with low cost, micro power consumption, and poor performance. These nodes are often burdened with complex image processing tasks, a considerable portion of which require the participation of 2D-DCT or 2D-IDCT
Summary
DFT is a common tool for frequency domain analysis of discrete signals and systems, but it is inconvenient to process image and voice data due to the need for complex domain operations. For example, are widely used in habitat monitoring, target detection, and espionage [10, 11], where nodes typically use processors with low cost, micro power consumption, and poor performance These nodes are often burdened with complex image processing tasks, a considerable portion of which require the participation of 2D-DCT or 2D-IDCT. (i) To the best of our knowledge, we are the first to propose such an outsourcing protocol for 2D-DCT and 2D-IDCT, and we are the first to accelerate the operational efficiency of 2D-DCT and 2D-IDCT from the perspective of cloud computing outsourcing (ii) Through carrying out theoretical analysis and simulation experiments, it is shown that the proposed protocol handles the three challenges faced in computing outsourcing well (iii) In the proposed protocol, only a single round of communication is required and the key management work is simple, which is suitable for the outsourcing of 2D-DCT and 2D-IDCT with arbitrary block size.
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