powx[i], p) } p <<= 1 if p&0x100 != 0 { p ^= poly } } } // Multiply b and c as GF(2) polynomials modulo poly func mul(b, c uint32) uint32 { i := b j := c s := uint32(0) for k := uint32(1); k < 0x100 && j != 0; k <<= 1 { // Invariant: k == 1<<n, i == b * xⁿ if j&k != 0 { // s += i in GF(2); xor in binary s ^= i j ^= k // turn off bit to end loop early } // i *= x in GF(2) modulo the polynomial i <<= 1 if i&0x100 != 0 { i ^= poly } } return s } // Test all mul inputs against bit-by-bit n² algorithm. func...