A canary trap is a method for exposing an information leak by giving different versions of a sensitive document to each of several suspects and seeing which version gets leaked. It could be one false statement to see whether sensitive information gets out to other people. Special attention is paid to the quality of the prose of the unique language in the hopes that the suspect will repeat it verbatim in the leak, thereby identifying the version of the document. Canary trap
That is quite an interesting story. We sent what appeared to be identical emails to all, but each was actually coded with either one or two spaces between sentences, forming a binary signature that identified the leaker.