1.1 Introduction

On its face, information in computers seems perfectly defined and certain. A bank account either has $1,432,442 or it has $8.32. The weather is either going to be 73 degrees or 74 degrees. The meeting is either going to be at 4 pm or 4:30 pm. Computers deal only with numbers and numbers are very definite.

Life isn't so simple. Advertisers and electronic gadget manufacturers like to pretend that digital data is perfect and immutable, freezing life in a crystalline mathematical amber, but the natural world is filled with noise, and numbers can only begin to approximate what is happening. Digital information comes with much more precision than the world may provide.

Numbers themselves are strange beasts. All of their certainty can be scrambled by arithmetic, equations, and numerical parlor tricks designed to mislead and misdirect. Statisticians brag about lying with numbers. Car dealers and accountants can hide a lifetime of sins in a balance sheet. Encryption can make one batch of numbers look like another with a push of a button.

Language itself is often beyond the grasp of rational thought. Writers dance around topics and thoughts relying on nuance, inflection, allusion, metaphor, and dozens of other rhetorical techniques to deliver a message. None of these tools are perfect and people seem to find a way to argue about the definition of the word "is".

This book describes how to hide information by exploiting this uncertainty and imperfection. This book is about how to take words, sounds,...