x^8+x^4+1
=x^8+2x^4+1-x^4
=(x^4+1)^2-x^4
=(x^4+1+x^2)(x^4+1-x^2)
= (x^4+2x^2+1-x^2)(x^4-x^2+1)
=[(x^2+1)^2-x^2](x^4-x^2+1)
=(x^2+x+1)(x^2-x+1)(x^4-x^2+1)