I would like to describe the manner in which a person performs a task as something like "done in a paranoid fashion." Suspiciously is close, but I'm thinking there should be something more like Paranoidly for this situation.
The use case is actually for documenting a software routine that is particularly untrusting of the input it is given. It acts as if the input is "out to get it," like a paranoid (person) might.
Right now my best succinct description is something like:
A paranoid routine for obtaining a widget based on supplied search criteria
but that doesn't quite capture the emphasis I was hoping for.
Obtain a widget based on supplied search criteria paranoidly