using System;namespace AES{ class AESLib { / Tables / public static byte[] s_box; public static byte[] inverse_s_box; public static byte[] inverse_s_box_hardcode = { 0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB, 0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB, 0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E, 0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25, 0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92, 0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84, 0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06, 0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B, 0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73, 0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E, 0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B, 0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4, 0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F, 0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF, 0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61, 0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D}; public static void init() { init_s_box(); } private static void init_s_box() { s_box = new byte[256]; //256 = 2^8 inverse_s_box = new byte[256]; byte p = 1, q = 1; //first values in the loop are 3 and 246 do { p = multiply(p, 3); //values of p begin as: 3, 5, 15, 17, 51, 85, 255 //Console.WriteLine("p = " + p); / dividing q by 3 = multiplying by 246 in GF(2^8) / //values of q begin as: 246, 82, 199, 180, 108, 36, 28 q = multiply(q, 246); //Console.WriteLine("q = " + q); int shift = q ^ cls(q, 1) ^ cls(q, 2) ^ cls(q, 3) ^ cls(q, 4); byte xor = (byte) (shift ^ 99); / The inverse s box is the opposite of the s-box, simply generated by switching value and index. / s_box[p] = xor; inverse_s_box[xor] = p; } while (p != 1); s_box [0] = 99; inverse_s_box [99] = 0; } / Circular left shift * returns x <<< y / private static byte cls(byte x, byte y) { y = (byte) (y % 8); byte a = (byte) (x << y); byte b = (byte) (x >(8 - y)); return (byte) (a | b); } / GF(2^8) multiplication method taken from https://en.wikipedia.org/wiki/Rijndael_MixColumns / private static byte multiply(byte a, byte b) { byte p = 0; for (int counter = 0; counter < 8; counter++) { if ((b & 1) != 0) { p ^= a; } bool hi_bit_set = (a & 128) != 0; a <<= 1; if (hi_bit_set) { a ^= 27; / x^8 + x^4 + x^3 + x + 1 / } b >>= 1; } return p; } public static void Main (string[] args) { init(); Console.WriteLine("[{0}]", string.Join(", ", inverse_s_box)); Console.WriteLine("[{0}]", string.Join(", ", inverse_s_box_hardcode)); } }}