TIME ANALYSIS COMPARISON OF HILL CIPHER AND AFFINE HILL CIPHER DECRYPTION USING MATLAB

Hill cipher system, it can be decrypted using the system 𝐶 = 𝑃 ∙ 𝐾 −1 (𝑚𝑜𝑑 𝑛) . Affine Hill cipher the decryption system expression is represented by 𝑥 = 𝐻 −1 (𝑦 − 𝑉)(𝑚𝑜𝑑 𝑛). We used English alphabet so 𝑛 = 26 because English alphabet consists of 26 letters. In this research, matrices of size 20x20, 100x100, 200x200 and 300x300. Although the decryption process of this cipher was simplified using Matlab, it still required a considerable amount of time, even for a program. The results obtained from Matlab showed that as the size of the matrices increased, decryption became progressively more difficult. Using Matlab for Hill cipher decryption is 𝑡 = 𝑐𝑝𝑢𝑡𝑖𝑚𝑒, 𝑎 = 0 + 100 ∗ 𝑟𝑎𝑛𝑑(20,20), 𝑏 = 𝑟𝑜𝑢𝑛𝑑(𝑎), 𝑥 = 0 + 25 ∗ 𝑟𝑎𝑛𝑑(20,1), 𝑘 = 𝑟𝑜𝑢𝑛𝑑(𝑥), 𝑔 = 𝑏 ∗ 𝑘, 𝑐 = 𝑖𝑛𝑣(𝑏), 𝑦 = 0 + 25 ∗ 𝑟𝑎𝑛𝑑(20,1), 𝑗 = 𝑐 ∗ 𝑦, 𝑙 = 𝑟𝑜𝑢𝑛𝑑(𝑗), 𝑝 = 𝑚𝑜𝑑(𝑙, 26), 𝑧𝑎𝑚𝑎𝑛 = 𝑐𝑝𝑢𝑡𝑖𝑚𝑒 − 𝑡. Using Matlab for Affine Hill cipher decryption is 𝑡 = 𝑐𝑝𝑢𝑡𝑖𝑚𝑒, 𝑦 = 0 + 25 ∗ 𝑟𝑎𝑛𝑑(20,1), 𝑘 = 𝑟𝑜𝑢𝑛𝑑(𝑦), 𝑚 = 0 + 25 ∗ 𝑟𝑎𝑛𝑑(20,1), 𝑛 = 𝑟𝑜𝑢𝑛𝑑(𝑚), 𝑝 = 𝑘 − 𝑛, 𝑎 = 0 + 100 ∗ 𝑟𝑎𝑛𝑑(20,20), 𝑏 = 𝑟𝑜𝑢𝑛𝑑(𝑎), 𝑐 = 𝑖𝑛𝑣(𝑏), 𝑙 = 𝑐 ∗ 𝑝, 𝑟 = 𝑚𝑜𝑑(𝑙, 26), 𝑧𝑎𝑚𝑎𝑛 = 𝑐𝑝𝑢𝑡𝑖𝑚𝑒 − 𝑡. This is the result of operations performed using Matlab.