inversion-sbox.md

inversion S-box — x⁻¹ partial rounds with reduced count replace x⁷ S-box in partial rounds with field inversion x⁻¹. reduce partial rounds from 64 to 16. the two changes are inseparable — x⁻¹ enables the round reduction. the insight field inversion x⁻¹ = x^(p-2) over Goldilocks has algebraic degree…