Hi,

in order to build composite field of $\displaystyle GF((2^2)^2)^2$ i need 3 irreducible polynomial as the following

$\displaystyle r(z) = z^2 + \lambda z + 1$ for $\displaystyle GF(2^8)/GF(2^4)$
$\displaystyle s(y) = y^2 + \{\delta+1\}y + 1$ for $\displaystyle GF(2^4)/GF(2^2)$
$\displaystyle t(x) = x^2 + x + 1$ for $\displaystyle GF(2^2)/GF(2)$

how do i determine all the 8 possible value for $\displaystyle \lambda$?

thanks in advance