...configuration.
The logical depth of a sequence is the running time of the shortest program which computes the sequence[1].

...troops
Americans of a certain generation may think of ``Cap'n Crunch Secret Decoder Rings".

...key.
The CA system mentioned above does not fall prey to this attack since it is composed of several different rules performing different stages of encryption.

Howard A. Gutowitz
Tue Dec 12 23:34:36 MST 1995