dChan
Anonymous ID: 2b954a Code to generate the AES S-Box March 22, 2019, 8:20 p.m. No.5838395   🗄️.is 🔗kun

using System;namespace AES{ class AESLib { / Tables / public static byte[] s_box; public static byte[] s_box_hardcode = {0x63 ,0x7c ,0x77 ,0x7b ,0xf2 ,0x6b ,0x6f ,0xc5 ,0x30 ,0x01 ,0x67 ,0x2b ,0xfe ,0xd7 ,0xab ,0x76 ,0xca ,0x82 ,0xc9 ,0x7d ,0xfa ,0x59 ,0x47 ,0xf0 ,0xad ,0xd4 ,0xa2 ,0xaf ,0x9c ,0xa4 ,0x72 ,0xc0 ,0xb7 ,0xfd ,0x93 ,0x26 ,0x36 ,0x3f ,0xf7 ,0xcc ,0x34 ,0xa5 ,0xe5 ,0xf1 ,0x71 ,0xd8 ,0x31 ,0x15 ,0x04 ,0xc7 ,0x23 ,0xc3 ,0x18 ,0x96 ,0x05 ,0x9a ,0x07 ,0x12 ,0x80 ,0xe2 ,0xeb ,0x27 ,0xb2 ,0x75 ,0x09 ,0x83 ,0x2c ,0x1a ,0x1b ,0x6e ,0x5a ,0xa0 ,0x52 ,0x3b ,0xd6 ,0xb3 ,0x29 ,0xe3 ,0x2f ,0x84 ,0x53 ,0xd1 ,0x00 ,0xed ,0x20 ,0xfc ,0xb1 ,0x5b ,0x6a ,0xcb ,0xbe ,0x39 ,0x4a ,0x4c ,0x58 ,0xcf ,0xd0 ,0xef ,0xaa ,0xfb ,0x43 ,0x4d ,0x33 ,0x85 ,0x45 ,0xf9 ,0x02 ,0x7f ,0x50 ,0x3c ,0x9f ,0xa8 ,0x51 ,0xa3 ,0x40 ,0x8f ,0x92 ,0x9d ,0x38 ,0xf5 ,0xbc ,0xb6 ,0xda ,0x21 ,0x10 ,0xff ,0xf3 ,0xd2 ,0xcd ,0x0c ,0x13 ,0xec ,0x5f ,0x97 ,0x44 ,0x17 ,0xc4 ,0xa7 ,0x7e ,0x3d ,0x64 ,0x5d ,0x19 ,0x73 ,0x60 ,0x81 ,0x4f ,0xdc ,0x22 ,0x2a ,0x90 ,0x88 ,0x46 ,0xee ,0xb8 ,0x14 ,0xde ,0x5e ,0x0b ,0xdb ,0xe0 ,0x32 ,0x3a ,0x0a ,0x49 ,0x06 ,0x24 ,0x5c ,0xc2 ,0xd3 ,0xac ,0x62 ,0x91 ,0x95 ,0xe4 ,0x79 ,0xe7 ,0xc8 ,0x37 ,0x6d ,0x8d ,0xd5 ,0x4e ,0xa9 ,0x6c ,0x56 ,0xf4 ,0xea ,0x65 ,0x7a ,0xae ,0x08 ,0xba ,0x78 ,0x25 ,0x2e ,0x1c ,0xa6 ,0xb4 ,0xc6 ,0xe8 ,0xdd ,0x74 ,0x1f ,0x4b ,0xbd ,0x8b ,0x8a ,0x70 ,0x3e ,0xb5 ,0x66 ,0x48 ,0x03 ,0xf6 ,0x0e ,0x61 ,0x35 ,0x57 ,0xb9 ,0x86 ,0xc1 ,0x1d ,0x9e ,0xe1 ,0xf8 ,0x98 ,0x11 ,0x69 ,0xd9 ,0x8e ,0x94 ,0x9b ,0x1e ,0x87 ,0xe9 ,0xce ,0x55 ,0x28 ,0xdf ,0x8c ,0xa1 ,0x89 ,0x0d ,0xbf ,0xe6 ,0x42 ,0x68 ,0x41 ,0x99 ,0x2d ,0x0f ,0xb0 ,0x54 ,0xbb ,0x16}; public static void Init() { InitSBox(); } private static void InitSBox() { s_box = new byte[256]; //256 = 2^8 byte p = 1, q = 1; do { p = multiply(p, 3); q = multiply(q, 246); int transform = q ^ cls(q, 1) ^ cls(q, 2) ^ cls(q, 3) ^ cls(q, 4); s_box[p] = (byte) (transform ^ 99); } while (p != 1); s_box [0] = 99; } / 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(", ", s_box)); Console.WriteLine("[{0}]", string.Join(", ", s_box_hardcode)); } }}

Anonymous ID: 2b954a March 22, 2019, 8:24 p.m. No.5838525   🗄️.is 🔗kun

Important to understand this modular arithmetic to understand AES. The reason multiplication has to have its own method is because multiplication over a nonprime Galois field GF(2^8) is not the same as multiplying two integers and moduloing the result to the modulus (as in a prime Galois field). It requires the use of a polynomial.

https://en.wikipedia.org/wiki/Finite_field_arithmetic#Rijndael.27s_finite_field

 

Above is implementation of this article in C#: https://en.wikipedia.org/wiki/Rijndael_S-box