Computational Complexity Analysis for a Class of Symmetric Cryptosystems Using Simple Arithmetic Operations and Memory Access Time

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Analytical Complexity Analysis

In this section we provide analytical derivation for the time required for encryption using different symmetric block cryptosystems. We perform the analysis for DES, 3-DES, AES and M-DES cryptosystems. In this analysis, we will break down the operations performed on the data for each cryptosystem into simple byte-wise AND, OR, XOR, Shift and memory access operations. In general, the total required time to encrypt one block of data is given by the number of operations that are required to encrypt this data block multiplied by the clock cycle time for each operation. The following equation gives a general method for computing the total time required to encrypt one data block using any cryptosystem

(1) where is the total encryption time for one data block, and are the number of clock cycles required to perform one byte-wise XOR, AND, OR, Shift and memory access operations respectively. And are the clock cycle times for one byte-wise XOR, AND, OR, Shift and memory access operations respectively.