"...The secret cipher caused concerns that NSA had deliberately made the cipher weak in order to assist its intelligence efforts....the scheme included a special escrow key held by the government for use by law enforcement, for example in wiretaps." -wikipedia on cryptography
Here is a page full of light pollution examples. Look at those and think in terms of the energy wasted.
If the light was simply directed at the ground you could get away with fewer fixtures, lower wattage and actually *improve* nighttime visibility.
Encryption ain't no guarantee.
"...The secret cipher caused concerns that NSA had deliberately made the cipher weak in order to assist its intelligence efforts. ...the scheme included a special escrow key held by the government for use by law enforcement, for example in wiretaps." -wikipedia on cryptography