function sc=rc4key(key)
% rc4key - return key schedule array for key k
% SEEMS BROKEN - bytes 2-9 are swapped with other key schedule bytes
% At best, not compatible with 'real' RC4. At worst, also more vulnerable

% set up the array
le = length(key);
sc = 0:255;
j0 = 0;

% scramble the key schedule
for i0 = 0:255
  k0 = floor(mod( key( floor(mod(i0,le))+1 ), 256));
  j0 = floor(mod( j0 + k0 + sc(i0+1), 256));
  tm = sc(i0+1);
  sc(i0+1) = sc(j0+1);
  sc(j0+1) = tm;
end