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Siguiente: Field operations with the Arriba: Field operations with the Anterior: Multiplication

Addition

What has been done for the multiplication can also be done for the addition in the Galois field $\mathbb{F}_{2^n}$. Indeed, addition is performed as the polynomial addition reduced modulus 2. Using the above identification the field addition determines the operation

\begin{displaymath}\oplus: [\![0,2^n-1]\!]\times[\![0,2^n-1]\!]\to [\![0,2^n-1]\...
...h $\delta$}}) \mapsto I_{\mbox{\scriptsize\boldmath $\gamma$}},\end{displaymath}

where the vector index $\mbox{\boldmath$\gamma$}$ is such that $p_{\mbox{\scriptsize\boldmath$\gamma$}}(X)=p_{\mbox{\scriptsize\boldmath$\epsilon$}}(X) + p_{\mbox{\scriptsize\boldmath$\delta$}}(X)$. In tables 12-16 these operations are displayed for $n=2,3,4,5$ respectively.


Table: Addition table in $[\![0,2^2-1]\!]$ corresponding to addition in the Galois field $\mathbb{F}_{2^2}$.
\fbox{$\begin{array}{rrrr}
0 & 1 & 2 & 3 \\
1 & 0 & 3 & 2 \\
2 & 3 & 0 & 1 \\
3 & 2 & 1 & 0
\end{array}$} Image vb2
(a) (b)



Table: Addition table in $[\![0,2^3-1]\!]$ corresponding to addition in the Galois field $\mathbb{F}_{2^3}$.
\fbox{$\begin{array}{rrrrrrrr}
0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 \\ 1 & 0 & 3 & 2 &...
...\\
6 & 7 & 4 & 5 & 2 & 3 & 0 & 1 \\ 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0
\end{array}$} Image vb3
(a) (b)



Table: Addition table in $[\![0,2^4-1]\!]$ corresponding to addition in the Galois field $\mathbb{F}_{2^4}$.
\fbox{$\begin{array}{rrrrrrrrrrrrrrrr}
0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & ...
...5 & 14 & 13 & 12 & 11 & 10 & 9 & 8 & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0
\end{array}$}
(a)

Image vb4
(b)



Table: Addition table in $[\![0,2^5-1]\!]$ corresponding to addition in the Galois field $\mathbb{F}_{2^5}$ (numeric values).
\begin{table}{\small
\begin{center}
\fbox{$\begin{array}{r@{\;}r@{\;}r@{\;}r@{\;...
... 9 & 8 & 7 & 6 & 5 & 4 & 3 & 2 & 1 & 0
\end{array}$}
\end{center}}\end{table}



Table: Addition table in $[\![0,2^5-1]\!]$ corresponding to addition in the Galois field $\mathbb{F}_{2^5}$ (density plot).



next up previous contents
Siguiente: Field operations with the Arriba: Field operations with the Anterior: Multiplication
Guillermo M. Luna
2010-02-19