Digital Image Encryption Based On GPGPU

With the rapid development of Internet and digital multimedia technology, the transmission ofthe confidential digital image through network has attracted much attention. Due to the intrinsicproperties of images such as bulky data capacity, high redundancy and strong correlation amongimage pixels, the classical encryption algorithms, such as DES and AES, can hardly meet therequirements of real-time image transmission. As a deterministic nonlinear phenomenon, the Chaoswhich has many characteristics, such as pseudo-randomness, ergodicity and highly sensitivity to theinitial state, has been widely used in digital image encryption technology. Recent years, a variety ofchaos-based image encryption algorithms have been reported, which greatly enrich the content ofthe image cryptography. However, the majority of the current image encryption algorithms do nottake into account the parallelism of the image encryption, which means they can only run on theCPU in serial manner. As a result, the current image encryption algorithms can still not meet therequirements of speed and therefore they cannot be widely employed in real-time imagetransmission. For real-time image transmission, there is no any application value for an encryptionalgorithm with low speed. How to design an efficient and secure image encryption algorithm is amajor challenge for the protection of image content.As a new massively parallel processor, the General-Purpose GPU (GPGPU) has been appliedto various fields for its powerful parallel computing capability. In order to take full advantage of thepower of GPGPU, the digital image encryption technology solutions based on GPGPU computingis researched in this paper. And two OpenCL-based parallel image encryption algorithm, i.e., CSIMand CBLP encryption algorithm are proposed. The CSIM algorithm consists of the pixel positionpermutation operation and matrix multiplication operation, and the image will be confused by thepixel position permutation and diffused by the matrix multiplication operation. The CBLP algorithmincludes the pixel position permutation operation, bit rotation and XOR operation, and therefore theimage is confused by the pixel position permutation and diffused by the bit rotation and XORoperation.Some experiments have been made to verify the security and efficiency of the CSIM andCBLP algorithm from the aspects of encryption efficiency, key space and sensitivity, histogram,information entropy, the correlation of adjacent pixels and plaintext sensitivity. Simulation resultsand numerical analysis show that both CSIM and CBLP algorithm are secure enough to resist somekinds of attacks, such as brute-force attacks, statistical attacks, differential attacks and known/chosen-plaintext attack. Moreover, that the high parallelism of our algorithms makes CBLP and CSIM are suitable to be accelerated by GPGPU, which as a result, the two algorithms can achievehigh efficiency in encryption/decryption process. Therefore, both the two image encryption schemesproposed in this paper are efficient and secure enough to be applied to the practical application.