source 2007 Hisil--Carter--Dawson parameter b assume b = a - 1 compute E = S1^2 compute F = C1^2 compute G = E^2 compute H = F^2 compute J = 2 H compute K = 2 J compute L = (2 F+E)^2-G-K compute M = b G compute N = K+J compute P = M^2 compute R = N M compute U = M L compute V = H^2 compute W = H L compute S3 = S1(R+b W+2(P-V)-W-P-V) compute C3 = C1(2(P-V)-U+P+V-R+b U) compute D3 = D1(U-P-V+R+b W) compute Z3 = Z1(R-b U-W-P-V) compute SC3 = S3 C3 compute DZ3 = D3 Z3