Kod för att lösa en algebraisk ekvation över GF(2), den så kallade SHI-1.

%% Program for solving the linear equations of SHI1

basis = []

for n = 1:11

% Bit n must be 1

A = [zeros(1,80)];

b = [ zeros(75,1)];

A(1,n) = 1;

b(1,1) = 1;

% Must be an expansion of m

for i = 12:80

u = zeros(1,80);

u(i) = 1; u(i-3) = 1; u(i-8) = 1;

if (i - 14) > 0

u(i-14) = 1;

end

if (i - 16) > 0

u(i-16) = 1;

end

A = [A ; u];

end

% Last five bits must be zero

A = [A; zeros(5,75) eye(5)];

basis = [basis gflineq(A,b)];

end

% independent basis

gfrank(basis')

% check if match

for i = 17:80

if not (basis(i,1) == mod(basis(i-3,1) + basis(i-8,1) + basis(i-14,1) + basis(i-16,1), 2))

echo 'No match'

i

%break

end

end