[jcims]

It should probably just default the s-box to all zeroes or some other method of deriving it ex-nihilo, but a default is practical just so you don't need to synchronize s-boxes between uses.

I would imagine anyone interested in using this for serious business™ would start with a new s-box hierarchy.

[owenmarshall]

An all zero s-box would give some, how shall we say, useful toeholds to an attacker.

That's not how S-boxes work, and crypto is best done with sane defaults.