Concealment: Pocket
A clever device the size and shape of a jeweler's glass. The lens of the decoder consists of over 500,000 optic fibers bent in a unique fashion. Each decoder corresponds with one and only one encoder.
To encode a message, a technician selects an intense color (a bright red-orange, for example) which is to be used for the coded message. A short message of less than 100 words is written in this color. The encoder, which itself has hundreds of thousands of fibers, photographs the message through the fibers, thereby scrambling the message into a series of apparently random orange dots. These dots are then spaced further apart, but the relative space between the dots is retained. The dots are printed on white paper to form a portion of a peach colored piece of stationery. The rest of the stationery's coloring is a collection of the same sort of dots. A message of the most innocuous sort is written on the stationery, being careful that the written message does not cover the encoded message. An agent in the field merely scans the stationery with the decoder until the encoded message is found.