A 2.4GHz retro-directive array operating in a multipath rich environment is utilised to spatially encrypt digitally encoded data.

For the first time digital data with no mathematical encryption applied to it can be successfully recovered only when it is detected within a highly constrained spatial region co-located close to the position of the reference signal.

This means that the signal cannot be intercepted and its modulated data recovered at locations other than the constrained spatial region around the position from which the retro-directive communication was initiated. Thus we say that it is spatially encrypted.