Barium Meal Test
According to the book Spycatcher by Peter Wright (published in 1987) the technique is standard practice that has been used by MI5 (and other intelligence agencies) for many years, under the name "Barium meal test". A Barium meal test is more sophisticated than a canary trap because it is flexible and may take many different forms. However, the basic premise is to reveal a secret to a suspected enemy (but nobody else) then monitor whether there is evidence of the fake information being utilised by the other side. For example, the double agent could be offered some tempting "bait" e.g. be told that important information was stored at a dead drop site. The fake dead drop site could then be periodically checked for signs of disturbance. If the site showed signs of being disturbed (in order to copy the microfilm stored there) then this would confirm that the suspected enemy really was an enemy e.g. a double agent.
Read more about this topic: Canary Trap
Famous quotes containing the words meal and/or test:
“For the first time I’m content to see
What poor mortar and bricks
I have to build with, knowing that I can
Never in seventy years be more a man
Than now a sack of meal upon two sticks.”
—Philip Larkin (1922–1986)
“Experimental work provides the strongest evidence for scientific realism. This is not because we test hypotheses about entities. It is because entities that in principle cannot be ‘observed’ are manipulated to produce a new phenomena
[sic] and to investigate other aspects of nature.”
—Ian Hacking (b. 1936)