Steganography

upright=1.4|thumb|The same image viewed by white, blue, green, and red lights reveals different hidden numbers.

German writer

substance used for writing which is invisible and can later be made visible

type of cipher

digital watermark which certain color laser printers and copiers leave on every single printed page, allowing to identify the device with which a document was printed and giving clues to the originator

thumb|NSA photo of microdots taped inside the label of an envelope. The envelope was sent by Operation Bolívar|German spies in Mexico City to [[Lisbon during World War II, but was intercepted by Allied intelligence.]]

Microprinting is the production of recognizable patterns or characters in a printed medium at a scale that typically requires magnification to read with the naked eye. To the unaided eye, the text may appear as a solid line. Attempts to reproduce by methods of photocopy, image scanning, or pantograph typically translate as a dotted or solid line, unless the reproduction method can identify and recreate patterns to such scale. Microprint is predominantly used as an anti-counterfeiting technique, due to its inability to be easily reproduced by widespread digital methods.

steganography method

Printing of documents protected against counterfeiting

Steganalysis is the study of detecting messages hidden using steganography; this is analogous to cryptanalysis applied to cryptography.

method for exposing an information leak by giving different versions of a sensitive document to each of several suspects

type of computer security attack that creates a capability to transfer information objects between processes that are not supposed to be allowed to communicate

computer program or script written in a valid form of multiple programming languages