Canary trap

A so-called Kanarienvogelfalle ( also called 'the canary trap, "canary " popularly referred a spy / traitor ) is a method for the detection of information leaks. These different versions of sensitive documents are given to the group of suspects to check which version is passed. The differences between versions are minimal and usually barely visible for a human. For example, commas can be inserted or omitted, of course, without this change the meaning of the text considerably.

The name comes from the novel Patriot Games by Tom Clancy. The protagonist Jack Ryan describes the technique, which he plans for identifying the original sources of the documents.