// (polynomials over GF(2)) modulo the irreducible polynomial x⁸ + x⁴ + x³ + x + 1. // Addition of these binary polynomials corresponds to binary xor. // Reducing mod poly corresponds to binary xor with poly every // time a 0x100 bit appears. const poly = 1<<8 | 1<<4 | 1<<3 | 1<<1 | 1<<0 // x⁸ + x⁴ + x³ + x + 1 // Powers of x mod poly in GF(2). var powx = [16]byte{ 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, } // FIPS-197 Figure 7. S-box substitution...