DIVERSITY AES IN MIXCOLUMNS STEP WITH 8×8 CIRCULANT MATRIX

In AES MixColumns operation, the branch number of circulant matrix is raised from 5 to 9 with 8×8 circulant matrices that can be enhancing the diffusion power. An efficient method to compute the circulant matrices in AES MixColumns transformation for speeding encryption is presented. Utilizing 8×8 involutory matrix multiplication is required 64 multiplications and 56 additions in in AES Mix-Columns transformation. We proposed the method with diversity 8×8 circulant matrices is only needed 19 multiplications and 57 additions. It is not only to encryption operations but also to decryption operations. Therefore, 8×8 circlant matrix operation with AES key sizes of 128bits, 192bits, and 256 bits are above 33.5%, 33.7%, and 33.9% faster than using 4×4 involutory matrix operation (16 multiplications, 12 additions), respectively. 8×8 circulant matrix encryption/decryption speed is above 79% faster than 8×8 involutory matrix operation. Ultimately, the proposed method for evaluating matrix multiplication can be made regular, simple and suitable for software implementations on embedded systems