This may not be SFF, although I have a vague feeling that at least one of the stories involving the main character has fantastical elements to it.
The story (possibly a series of stories) involves a man who is either a detective or secret agent or something similar.
All I can now remember is an incident where he encounters his boss (possibly at the end of a case/adventure) who has a machine that destroys confidential documents by converting them into a sort of porridge (by chewing them up presumably). The boss remarks that there is more than one model. One of which has a light on it that has no obvious purpose to the reader I think.
Making the documents into porridge is explained as making it much harder to reconstruct them.