In Galois Field Multiplication is performed as a binary multiplication between the two binary values representing polynomials and then is reduced by a reduction polynomial
So if i have the binary value $111$ represented as $X^2 + X + 1$ being multiplied by itself, the textbook claims in $GF(2^3)$ the answer should be $X + 1$ if reduced by a polynomial $X^3 + X + 1$ or in binary $1011$
Here is my answer
$111 \times 111$
----$110001$ $\longrightarrow$ Value after binary multiplication
XOR $1011$ $\longrightarrow$ Reduction polynomial
at the last step after reduction I'm left with
-----$1011$
XOR $1011$
-----0000<----- value is zero then why does the table say $111 * 111$ in $GF(2^3)$ is $011$ or $X+1$
111x111 is not exactly the same in normal number multiplication
in this group, 111x111=10101
there is no carry, each digit is represented as the coefficient in polynomial, and it is computed modular 2
then 10101 mod 1011 = 11