When an SB represents L??? or X??? (where L is an LT and X is a non-linear transform), then if m=n, and L or X is bijective, the SB for L??? or X??? bijection is locally secure: irrespective of L or X, we can always choose an input or output coding such that the SB of L??? or X??? is that SB. Locally, any information about L or X, other than the value of n and that it is a bijection, cannot possib