A canary trap is a method for exposing an information leak, that involves giving different versions of sensitive information to each of a group of suspects and seeing which version gets leaked.

The term was coined by Tom Clancy in his novel Patriot Games . The hero, Jack Ryan (fictional character), describes the technique he devised for identifying the sources of leaked classified documents:

: Each summary paragraph has six different versions, and the mixture of those paragraphs is unique to each numbered copy of the paper. There are over a thousand possible permutations, but only ninety-six numbered copies of the actual document. The reason the summary paragraphs are so—well, lurid, I guess—is to entice a reporter to quote them verbatim in the public media. If he quotes something from two or three of those paragraphs, we know which copy he saw and, therefore, who leaked it. They ve got an even more refined version of the trap working now. You can do it by computer. You use a thesaurus program to shuffle through synonyms, and you can make every copy of the document totally unique.

By making sure that each copy of the document differs slightly in its wording, if any copy is leaked then it is possible to determine who sang .

The technique of embedding significant information in a hidden form in a medium has been used in many ways, which are usually classified according to intent:

=See also=

*Watermark *Steganography *Honeypot

=External link=